You can use a hair dryer to heat the board up to failure. When the failure shows up, use a can of freeze mist, one chip or component at a time, until it works. That will identify your thermally intermittent part.
Thanks for making the video. I worked for NCR Corp from 1978 to 2003. I have a lot of memories repairing those Halk drives. Head crashes were very common and hearing the heads screeching on the platter you can never forget! Nothing like walking into a office building with a 20 lb tool briefcase and a 20 lb oscilloscope was a distinctive sign you were the geek of the times. And yes under the suit coat was a pocket protector.🤓 PS: most head crashes were due to the micron filter being clogged.
I am of the 486 vintage! And I can clearly recall that most of the people back then in most offices I have been to used to smoke, a lot 🤣 hence, most of the machines I scavenge from that era, have a certain yellow grimy patina that coated most of everything, and it was way worse on the ventilation side of things. Hence I can only imagine what these drives had to endure back then 😅
This takes me back. My first job in the late 1970's was as an engineer with a Wang computer dealer. For removable drive storage both Hawk and Phoenix drives could be attached. One of our jobs was to fix these drives when they went wrong - but back then you could order replacement parts! Our most common problem was when data errors were reported. This usually occurred either because the heads had drifted out of alignment or there had been a head crash. In either case a head alignment process had to be undertaken. This involved connecting the drive to a special diagnostic control unit, attaching a scope and carefully adjusting the head position until the scope showed the correct waveform whilst controlling the drive from the control unit. Over time you got a 'feel' for the alignment. Also I recall that the air filters had to be changed at regular intervals as they could get clogged (especially if they were in a smokey office environment which was common back then) and fail to remove dust particles properly which could cause a heads crash. One of the features of the Phoenix drive was that it had several fixed platters - but depending upon which model was purchased depended upon how many of these platters could be used and hence the capacity of the unit. But the number of fixed platters that could be used was determined by links on the control board - the drive being the same for all capacities! One of our jobs when installing these systems was to configure these links to correspond to what had been ordered. Or if the customer had initially ordered a small drive and then paid for an 'upgrade' to a larger model we just adjusted the links and hey-presto the customer had a larger capacity drive
@@markmuir7338 Back in the 1970's you could get disk drives which took a 200Mb removable disk pack which had 10 platters giving 20 sides of 10Mb each. These were big beasts and if there were several connected (you could have up to 8) you could feel the vibration in the room when they in use. Head crashes were a nightmare!
@@robertlewis4216 Possible with the 2200 MVP,, but I used these 200Mb types with PDP-11s. It was more usual to have the 200Mb drives with the Wang VS computers. I used Hawk or Phoenix drives with Wang 2200 VP/MVP computers. Then Wang brought in sealed hard drives (I think 8" Winchester?). These tended to go out of alignment with use and you had to adjust them using a scope. You could tell if they were out of alignment as they just kept seeking and seeking and seeking which you could hear.
It's important to understand that "erase" is a misnomer, the read/write head by itself is perfectly capable of obliterating the old data and writing over it. But magnetic gaps like in a read/write head have "fringing fields", like when you look at a magnetic field with iron filings, the magnetic field lines leak out beyond the gap in the head. This is still true for the latest hard drives today. The "erase" head simply blanks out a thin area on either side of the track so that it doesn't interfere with the next track over. Is that wasteful? Sure. That's why you have SMR recording on modern hard drives, they only erase one side so you can record closer together. Ideally the function should have been called "guard banding", but we're stuck calling them "erase head". So what's the difference? The timing of when the "erase" coil is powered up when writing. It's a very low-level function. There shouldn't be such a great difference in performance. Why they make different types of heads, I think boils down to what was easier to manufacture. Straddle erase heads seem to have been replaced very early on with tunnel erase heads on floppy drives, for example, but the only change was in timing in the FDC. Search for the Motorola AN917 "Reading and writing in floppy disk systems using Motorola integrated circuits", it's for floppy disks, but I think the ideas are the same. I won't put a link because the comment won't make it.
Ex-Burroughs guy here. We used comparable drives on the very smallest machines, and my understanding is that straddle-erase is not actually to erase data (before writing) but to trim the somewhat marginal flux pattern laid down by the edge of the write head to improve reliability and potentially to allow more TPI (less inter-track crosstalk for a given separation). That might explain why the documents you were looking at showed the flux pattern differently: the illustration of the PE showed the written flux looking like a triangular wave while that of the SE trimmed the top and bottom (although the illustrator didn't quite understand what he was being asked to draw, so rounded it off). Don't know whether this will work, but /\/\/\ vs /-\_/-\_/-\ If the drive you've got similarly uses SE to increase density, there's also a possibility that the formulation of the oxide on the surface of the disc is different which might contribute to compatibility (or at least reliability) issues. As a footnote, we were trained during the early eighties to use iso on a lint-free (wrapped around a ruler borrowed from the customer) when doing an on-site repair, then to flush any remaining impurities off the surface with a liberal amount of Freon. Perhaps fortunately, they'd stopped issuing Freon as a cost-cutting exercise... Updated: I've got a very hazy recollection that one type of erase might have been for removable platters, and the other for fixed where (a) interchangeability wasn't an issue and (b) since the ring holding the platter was torqued down the overall dimensional accuracy was better and there was an incentive to try to increase the TPI.
Yes, either Kim-tech wipe replaced frequently or in a pinch coffee filters are relatively lint free. Always had a steel 6 inch scale in the pocket protector.
@@mikebarushok5361 We were still issued with packs of genuine lint-free cloths, together with the spring-pullers and link-benders needed by every electronics guy in the early 80s. And for those disks you needed more than a 6" ruler: clean while spinning and that edge is /aggressive/ :-)
@@button-puncher Presumably because it's easily-distilled to high purity but... heavens. Out of curiosity, roughly what year was that? It would be interesting to know when attitudes changed.
@@MarkMLl_uk My prof was talking about it in the late 90's. The US made it's sale/production illegal in 1995. It was supposedly contributing to the depletion of the ozone layer. Considering that the ozone hole in the atmosphere is the same size as it was 30 years ago, it sounds more like the environmental "scientists" don't know what they are talking about. Yet again.
You are one step closer in understanding the system. That’s valuable information to have. Imagine if someone reaches out and says - “I have a hawk drive that doesn’t work with my system” and you discover that it’s a PE head drive and they need an SE head drive…
I get the idea that a controller card designed for SE can work with either type drive. SE requires separate erase and write passes, and PE will work fine when used that way. It's just PE cards can't work with SE drives because they do an optimized single erase+write pass, which can't work when both heads are in the same position.
@@monad_tcp As tinkering in one's home lab gets better over the decades, I wouldn't be surprised if people start making their own equipment and platters. After all, we have access to xray scanning equipment to reverse engineer heads and such now.
You seem like someone who would know. On the late seventies I had a friend who worked for a company which had a mini computer much like those you feature. After hours, he had permission to invite friends in for gaming. We played a game called "Orion III." It was a "Star Trek" like game where ship, planets and other visuals of the game were represented on screen by ascii characters. The amazing thing was... up to 16 people could play this game, in four teams of four. I remember the disk drive for the thing was huge; like a top-loading washing machine. There was a stack of platters in clear plastic holders... they would be lowered into the drive, then the plastic outer covering would be lifted out. The lid would be closed and the air pumped out before the disks were spun up. Have you heard of anything like that? I've been looking for the game specifically for a long time!
Yes, every single time I see one. I even started to wonder if one of the engineers thought about looping the wiring to put ears on either side of the head.
I love that you have become apart of how I unwind on Sundays. Get home from church, have my artisan coffee, light up my cigar or pipe and enjoy some vintage computing. Thank You!
Hey there! It's been 40 years since i've worked on any of those old CDC drives and my memory isn't that great anymore so maybe i'm remembering this wrong but I seem to recall that the straddle erase head doesn't work like you think they do.. it is there to trim the sides of the written data to ensure the guard bands are preserved, you got a nice narrow track and this allowed you to get a slight increase in data density, they are enabled at the same time as the write head. I recally a low and high TPI mode on these drives too and many machines of the time used a hard sectoring card that was adjustable via jumpers or switches, this drive might have different sectors or tpi to your other drives. Head crashes were almost always caused by a clogged filter so make sure you stay on top of those, I doubt the originals are available anymore but you can probably fabricate something with a 99% .3 micron hepa style filter should you need to. Anyhow best of luck with it all and apologies in advance if everything i wrote it totally inaccurate :)
This is the first video I've ever seen from you and I'd LOVE to see what's on this drive. There's just something about snooping around other people's long forgotten data from years if not decades ago that I just can't resist.
These drives used IBM 5440 disc packs, as did the first machine I ever programmed, an IBM, back in the 70s. The DEC RL drives also used these packs. They were known for their reliability and were usually rock solid. Nice seeing these things still spinning in Dave's garage
I've been thinking about that. Breaking taps has been doing silicon lithography, so I wonder if this is something that could be done today by "home" workshops.
I've been wondering where the original manufacturing of platters took place and what machinery was used. It would be awesome to see the original machinery refurbed and creating new platters.
Hawk Tuah Drive This is my first video I've encountered from this channel, and I am *heavily* intrigued by how this kind of tech almost makes enough sense to understand for someone like me who isn't an engineer, and the journey to keep it running is gonna keep me invested.
I can understand why the Phoenix drive scares you. I can still feel the cold brick in my stomach when i got a "system down" call and i knew thier primary drive was a Pheonix...
I love these drive videos! As a data center guy and vintage fan I get a kick out of the fact that these names "Hawk", "Phoenix" are still in use for server storage.
I remember seeing a very similar looking drive back in high school, just sitting in the back storage room of our tech department. The department was run by an older guy that used to work for some huge telecommunications company like Bell Canada if I remember correctly, pretty sure he was the one that donated it to the school. It was around the same size/shape as the Hawk drive in this video and also weighed an absolute ton, only it had three orange platters instead of one, and I think the frame had more of a golden/brass colour to it. Really cool to learn more about drives from this era and seeing one (more or less) in action, great video.
It's wild to me to think that 99% of the drive can be identical and it might as well be a completely different drive as far as the controller card is concerned!
@@UsagiElectric Terribly sorry but are you *sure* the straddle-erase needs a full revolution on CDC drives to overwrite data? Do you happen to remember from where do you know that? (No links please - youtube doesn't like those) I'm not knowledgeable in the subject and might be totally wrong but that's not how I understood the process. I thought in straddle-erase the write coil overwrites data while erase coils erase the guard-band, while with tunnel-erase heads the erasure happens a little ahead of time of writing That is what the jumper is supposed to change - it should introduce a delay between erase and write
@@jwhite5008 That's something I'm curious about, was the jumper on the drive PCB set correctly? Maybe you could also scope the output from the read amp to see if the signal is even written.
@@Stoney3K Actually I'm more interested in oscilogram of what is actually *read* from the platter. I think the issue might be unrelated to the head type. There is quite a lot that happens between issuing the format command and reading stuff back, and any of it can go wrong to produce such a result. Inconsistent head positioning or read/write attenuation for example See also my next comment
Your detective work, and comprehension, is inspiring. Something that seamed overlooked, or perhaps forgotten, you didn't mention installing a StradelErase head controller card. Is that possible (two separate controller cards)?
Thank you so much! Unfortunately, Centurion never made a straddle erase controller card, so we'd have to build one from scratch. But, since I already have two working Hawk drives with pre-erase heads, we'll instead shift focus to something else, and reserve the straddle erase Hawk for a different project.
I was thinking on the same lines, while looking at the schematics and wondering how hard would it be to modify the controller to use both types of heads (selectable of course) Shugart drives used this types of head, have to look at the schematics but I would assume the mods will have to be related to some sort of delay between the erase pulse and the write one.
@@UsagiElectric Someone (CDC?) made a RWE card set up for straddle-erase heads, or the heads themselves wouldn't exist. Whether said card would work in a Centurion is another matter. 🙂 My guess is that somewhere there is (or was) a PE-equipped drive plugged into a SE RWE board that writes at half the speed it's capable of.
My First IBM PC had a whopping 15MB storage and i could only fill it up to 5MB with so much software available back then. Hard Drives were like Hard Currency.
I was able to visit the LSSM in Pittsburgh last year and got the grand tour. It was one of the highlights of my visit to the states and can highly recommend this place. I even learned that I was wrong about a thing or two and since strive to do better.
Quite a blast from the past seeing that technology. I find it fascinating that you _like_ CDC drives. I used to operate a CDC Cyber 72-26... with an 808 drive attached. It was huge, and terrifying. It used a separate 1500psi hydraulic pump to drive the heads. Fortunately I got an offer to change jobs, and waved goodbye to that CDC forever.
@@Alexis_du_60 It was mainly terrifying Alexis. An 808 was tall - over 6 feet high. The platters were over 2 ft diameter, and there were a LOT of them. So that the heads did not droop as they were pushed towards the inner track, they rode a fixed steel bar that was about 3 inches diameter. So the huge mass of the head assembly did not cause the whole drive system to rock, they had two spindles, one on each side of the logic and head actuators. The two sides were driven in unison, in opposite directions. *Everything* about the 808 was massive... and despite the power applied through that hydraulic ram, they were slow to seek, with what had to be the longest latency in the rotating data storage game. So far I have not seen any reference to one on the web.
My mom and dad both worked for EDS for a good chunk of it's existence till it was bought out (funnily enough, they met when their two teams were having issues, and mom and dad were the two chosen to communicate between the teams). Our house is still is chock full of EDS whatsits; heck, I'm drinking out of an EDS mug right now! So hearing that name REALLY snapped my attention back to the video, lol!
Really takes me back to my first few years at work. The MRI I maintained used a 11/750 for the scanner and a 11/730 for the standalone viewing console. Both had removable packs. Something was really satisfying handling those packs.
RE: Fixed drive not writing. This reminds me of a customer of mine back in the 70's who had a removable pack Plessy drive. He was using this for archiving data. What he didn't realize was that the write protect indicator bulb was burnt out. The drive would accept a write command but would not indicate write fault. When he (we) figure this out, we examined his "most recent" archive, and the data on it was three years old! Lucky he didn't have to rely on an archive/backup. Check your write protect button and indicator bulb.
@@PCFixerthat sounds like vintage (Tomb of The) Cybermen to me... none of your new-fangled "Delete Delete Delete".... although, if it's a stradle erase head, should that be "Erase Write Erase"?
Back in the 80’s I had to get one of these CDC Hawk drives from one end of LA to the other, put it in the trunk of my Toyota Tercel,wound up with a dent pointing out from the sheetmetal of my trunk when the drive shifted around. Disk drive was fine.
Every time you talk about the EDS PC I am reminded of the TV show "Halt & Catch Fire". The story you tell of Centurion getting into the PC market is so much like the fictitious company Cardiff Electric in the show.
I think one easy way to describe the difference between pre-/straddle-erase heads is the coils in pre-erase heads are arranged in-line with/parallel to the data tracks and the coils in the straddle-erase heads are arranged perpendicular to the data tracks.
I remember learning about the AMD 2900 series, and how you could define your own instruction set in the microcode, this was back in the mid 80s, at Polytechnic (now converted to and called University). We had a great lecturer who was very excited about his subject. I hadn't realised it was used in so many systems.
I used to work on some Honeywell Level 6 machines and they had Hawk drives. Fixing a head crash on the fixed drive was comical. They pulled out the bad platter, took out the heads. Sanded the heads with fine sandpaper and then washed them out with high percentage alcohol. Then the would put in a new platter, reinstall the heads and format the drive. That worked - most of the time.
Watching a voice coil actuator was always impressive 'back in the day'. But what what was really awesome was the hydraulic actuators on the IBM S360! It seemed to me they were faster than the voice coils.
I wonder if you will be able to find the appropriate hawk controller. A head rewind attempt would also worth the search of somebody which have the right tools ( and ideally knowledge). Amazing machines.
Many years ago when I was a student, we had a VAX, and I recall a time when I was in the computer center, and we heard this horrible noise coming from the disk cabinet. But we were totally baffled in that the system was still up and running and had apparently suffered no ill effects. We shut the system down as a precaution. The DEC guy came out to repair the hard drive, and we found that the motor shaft had sheared off where it went into the brake, and the horrible noise was the two ends of the broken shaft grinding against each other.
Those drives greatly resemble the drives on Honeywell Level 6 Minicomputers from that time. I suspect they may be manufactured by a common OEM and then rebranded and sold by various other companies including Centurion. What that means is that there's a good change you can find parts like drive headswhich you seem to need from other stock and or drives if you can figure out who actually made the drives and who else used ones like yours for their equipment. Honeywell is still in business too so they may actually have some parts stored away in their parts stocks.
every hard drive I've worked with going back to the very early 70s (and those were designed in the early/mid 1960s) did flying erase/write in one pass. the erase gap was right in front of the write gap in the same head assembly, and both worked together.
Hot air rework station (for Surface Mount stuff) works well for precision heating of marginal components. Plus it gives you a reason to buy one if you don't already have one. LOL! I got a Quick 957DW a while back and it's really nice. I'm just a hobbyist. Didn't need anything more expensive.
Since you have an erase coil on either side of the write coil, with a straddle erase, you effectively erase before and after the location your are writing to. Which means that the data you are writing to the platter is erased after you write to it, no wonder you have corrupted data when you try to read it back. Since you have only four pins going to the head, presumably one pin for each coil with the fourth being a common, it would make sense to unpin the trailing erase coil, thereby converting the straddle erase into a pre-erase head. This might allow you to use this drive after all.
As much as I love these videos on these machines, I’m kinda nostalgic for the early tube days of the channel. It’s what brought me in, what you were doing was unique and fascinating. I’d argue it’s time for a bit (lol) of tube computing videos.
We'll be getting back to that soon, I promise! The paper tape reader for the 1-bit tube computer has gone through about three different design revisions over the past few months. I'm waiting on some new parts to arrive and then we'll start building prototypes and filming that. After UE-1 is finished, we're already working towards a design for UE-2. The reason there hasn't been any videos on that stuff in so long is because I'm trying to do a lot of the initial design work first, then get to work constructing and building it.
@@UsagiElectric excellent! Given what’s going on with Intel, I’d love to see people go revisit the 4004, perhaps using discreet logic chip, or, woooooo, transistors built into gates. I’d bet it could fit on a single 4x8 sheet of plywood using transistors.
Someone really needs to set up some virtual versions of these machines as teaching tools. It wasn’t until I started working with older more limited machines that I started truly understanding how computers work and how to write programs efficiently. Programming with extremely limited RAM and storage really forces you to think about cleaner more efficient ways of accomplishing tasks.
I think you are misunderstanding the straddle erase head. I think it means it straddles the full width of the track, a bit wider than the read write head. This is different to a tunnel erase head that has two thin strips that erase just the sides of the track. However, I don't understand why an erase head was needed for a digital drive as the write operation should overwrite any previous data. I think it was just to reduce noise from the edges of the track making head alignment less critical. I don't think any drives need two revolutions to do a write.
I found this info about floppy disk erase heads. From the Siemens manual, page 3-4: "The read/write head also contains a tunnel-erase or straddle-erase electromagnet, the function of which is to erase the edges of the recorded track as the data is being written. The width of the track is narrowed to approximately 0.013 inch by this technique, to minimize the effect of data previously written on the track and possible crosstalk between tracks." Discussion in the Siemens manual makes it clear that "tunnel erase" is one kind of head, and "straddle erase" is another kind of head; and that erase operation is concurrent with write. For instance pages 3-26 thru 3-29 describe the erase gating and logic during write: "The purpose of the auto erase feature is to provide the necessary turn-on delay between active WRITE and ERASE and the turn-off delay after WRITE goes inactive, but for tunnel-erase heads only. This is for option TE installed. Straddle-erase heads use option SE , which bypasses the delay circuits." A sketch of the tunnel-erased track shows that it measures .013 inches wide. The next document gives an explanation for why a delay is needed. A CDC (Control Data) application note "5.25 inch FDD format considerations and controller compatibilities" examines 8-inch drive technology and standards. It refers specifically to tunnel erase vs. straddle erase in the introduction, saying "The head style and drive tolerances determine the minimum gap of the 5.25-inch FDD formats". The two erase heads as used on 8-inch floppy drives are described on page 7 as follows: "Both head styles have as common parts a read/write gap and two erase gaps...The two erase gaps are used to erase guard bands on both sides of the data being written. These guard bands are necessary to to eliminate noise caused by old data that had been written slightly off track...A major difference between the two heads is the placement of the erase gaps....The erase gaps of the tunnel erase head are 36 mills behind the R/W gap whereas with the straddle erase head the gaps are on both sides of the R/W gap and extend approximately 11 mills behind it...Because the erase gaps of the tunnel erase head are so far from the write gap they must be turned on and off separately." Sketches of tracks for each head show that with the tunnel erase head, "used by IBM and most manufacturers", there is 6 mills of erase gap either side of the 13-mill track. With the straddle erase head "used by Shugart exclusively", each 6-mill erase gap is offset from the 13-mill track by 1-2 mills." So both types of head erase just the edges of the track and it is done while writing in the middle. Straddle heads do overlap the write head length wise so they are turned on at the same time. Tunnel heads are behind the write head so needed a delayed signal. On a floppy drive there isn't a separate erase signal so the delay for tunel heads must be in the drive logic, not the controller.
I remember back in my minicomputer days working on Data General equipment exclusively. DG used Phoenix drives I believe. As memory serves they were 10 MB per platter with 20 MB total (10 fixed and 10 removeable). We also had some much older Diablo 33 drives that were 5MB removable only but they were being phased out in favor of the higher capacity drives. There also were some washing machine sized drives with stacks of removable disks that I think were 80 or 120 MB (can't remember). Those were also much older but still in use back in the 1970's. I was never aware of the head differences. Quite interesting!
Need somebody out there with a watchmaker's precision to dissect some bad heads and come up with a way to make new ones or repair the old ones, there's certainly going to be a market for it!
We nowadays take hard drives for granted, they're even being seen more and more like an obsolete technology with the advancements of solid-state storage, but it's astonishing if you think to all the R&D magnetic storage technology had to go thru to become the rather normal thing it is today.
David, since the badly crashed HAWK head was trash as far as you are/were concerned, why not take a no-risk chance at repairing or at least disassembling it under a microscope to better understand how it was built? You've got nothing to lose! I bought a stereo-microscope in order to attempt repairing a known-failed tape read (or write?) head for a DECtape drive. My friend had another head, so he swapped them out and sent me the bad one in the off-chance that I could get lucky trying to repair it. I need to re-start _trying_ to repair it for him!
You should put a scope on the head signals to verify the write pulses get to the heads. The writes should be causing flux reversals no matter what. You could probably trigger on the sector pulses and get continuous view of a single sector, a bit like you did with the timing track on the Bendix drum. Then try some writes and see what happens. Also maybe try the same but disconnect the erase coil. Lastly check the pinouts? Maybe your SE heads are different.
I'm fairly sure you're wrong about it using two passes to write a sector with the straddle erase head. The data itself doesn't need erasing -- the data head erases the old data when it writes the new data. The erase heads are only there in case there's a misalignment between the old and new data tracks, to remove any spillover. Erasing and writing is still a single operation. From what I've read about this, the only difference should be that the pre-erase method might need a short delay between turning on the erase and write heads, because of the separation between them, whereas the straddle erase method would not need this delay because the heads are in line. Since your controller board seems to be telling the drive to turn on data and erase together, it would seem that any such delay, if required, must be implemented somewhere in the drive itself, and the controller doesn't need to know about it. So I suspect your problem isn't caused by the pre-erase vs. straddle-erase issue, there must be something else wrong.
Back in the day I seem to recall that main frame (ICL IBM etc) hard disks used significant air/vacuum filtration since the heads literally flew over the platter. Whilst a human hair would be pushed out of the way a smoke particle could cause a head crash. This may be an apocryphal story but I'm reminded of an issue, in Holland I believe, where for some reason a head crash occurred. Since work had to go on the removeable disk pack was tried in another reader. That crashed too. Now there are 2 readers destroyed. Nevertheless some bright spark tried another disk pack in the original reader with obvious results. Fortunately somebody with sense halted operations and called in the gurus to fix the fundamental issue. 5 1/4 inch disks held in the same hand as a cup of coffee can produce a similar effect. I know I watched it and had to sort it. The look on my boss' face when I took a pair of scissors to his precious disks will not be forgotten!
I had a strange idea: perhaps the heads coils could electrically be protected by adding a inline fuse. A small board could be made with a surface-mount fuse, which could be put between the head and board that reads the head. It the board goes, the head may be protected. Perhaps a few Zener diodes could clamp the voltage, a bit higher than its working voltage, too.
I haven't watched Pokémon since middle school, but I recognised that R immediately. Next episode I hope he'll put on that fetching cropped jacket they wore
Might consider a stethoscope to listen for any bad noises coming from the drives. Would amplify and pinpoint them beyond what the unaided ear could hear.
I wonder if you could get in touch with Lumafield to get the failed heads scanned. They did such collaboration with other channels so seems worth a try
That servo control board is going to be interesting to fix. I'm betting those cans are op amps, and i counted 10 of them. So any one of those op amps (if that's indeed what they are) could cause a failure. I'd bet good money that you have a couple of "instrument amps" for the reference and feedback signals, an error amp. The error amp would feed into probably at least a proportional amp and an integral amp (may even have a differential amp, but hose are tricky to get right). Then a summing amp to sum up the control signals (from the PID amps), then output amps to actually drive the voice coil. And this is ALL analog, so good luck with that! Plus, there's no guarantee those op amps are even available any more. Sure, a new servo board could be engineered, but the cost would be eye watering. Unless someone just decided to do it as a fun project. ^-^
18:45 This makes me wonder why they made the removable packs blue rather than clear. Checking for signs of a crash seems like a common enough thing to do, and noticing damage on the platter before inserting it could save heads. All of this would be much more immediately noticeable if it was clear or had a clear window.
@UsagiElectric Thank you for sharing your adventures with us! Keep up the good work! Is it possible to find someone who can rewind the coils on the heads that have blown coils? I know the wire is extreamly tiny, but there has to be a way to repair those heads.
The 120fps is neat, but I'd still like to see you do a collab with the slo-mo guys, with some stupid-high framerate capture of that chain printer in operation. My brain still refuses to believe that it's method of operation is a thing that can actually work in the real world.
When all heads fail: is there any documentation of how the head are designed and/or made? If you it should be doable to recrate them Otherwise once migt be able to disassamble an non-working head trying to reverse engeneer them Same spiel for the servo cards I know, i know it is a long and tedious project but we have come so far already
As seen at 27:44 the head mainly consists out of 2 transformers. And this is honestly how even a lot of modern hard drives are made these days with 20 TB drives as well. (except I think modern heads are MEMEs fabricated, since that is way easier...) But yes, one can sit under a microscope and hand wire a new head. Just need very steady hands and plenty of patience. How these heads were manufactured back in the day is a good question. I would not be surprised if they were manually wound by hand. Since that is how a lot of other things were made back in the 60's. (Magnetic core memory for an example were oftentimes manually threaded, a laborious task requiring a steady hand and plenty of patience.)
@@UsagiElectric well if you decide to go with a bus card similar to the og I always thought it would be cool to use Sega Genesis 64 pin cartridge connector or a SNES cart connector for a computer like that because unless you want to make exact clones it's ok to be different if its still compatible
A Micro-ATX Centurion Motherboard! What a dream that would be! Similar to the Monotech NuXT except it's a full-Centurian Computer rather than an IBM PC!
As long as it has a thermal printer, I'm keen. Peripherals are the one thing people always forget about in vintage tech. They were the core part of what made them worth buying.
I have found some discussion regarding the head configuration on the larger floppy drives. The straddle configuration just trims the written track left and right to create some security gap to the neighbour tracks and to erase potential remains from an old track that can be left over due to slight positioning errors. Trimming the track can happen simultaneously or after writing, so these additional heads can also be behind the write head. From what I understand erasing and writing is still done simultaneously, but the timing of the erase gate must be adjusted in relation to the write gate according to the head configuration which is irrelevant on floppy drives as this is handled internally. How is this implemented on the hawk drive? Are both gates exposed on the interface to the controller card?
@@liquidsonly Yes,... no-a-days, programmers just add libraries, and code, no thought of how efficient you need to be... We definitely lost some skillz over the years... but we have also gained in amount of data you can process... I still love them old early 80's feelings..
That's 5 million ASCII characters without compression. That's a lot of text to type. Of course if you add images it will bloat up the document quickly.
After seeing the differences between Pre-Erase and Straddle-Erase, it looks like the biggest problem is one of timing. The pre-erase head needs to have the erase head powered up for one "bit" time-length before the bit is actually written to the drive, while the straddle-erase can power up the erase head and the write head at the same time as writing the bit. There's no need to pre-erase the bit since writing the same bit to the same place won't change the magnetic field in that position, and writing the opposite bit to that location should just overwrite the bit which used to be there. It looks like the straddle erase head is more mechanically complicated than the pre-erase head, which is probably why straddle erase came later, but it should be easier to interface to it due to not having to juggle the timing so that the erase head wipes a bit followed by the write head writing to the same bit as you need to do in order to use pre-erase heads. Edit: Well, if they're powering both the erase head and the write head up at the same time, that means there must be some wasted space at the start and end of each sector when using pre-erase. That complicates things even more.
There might be circuitry inside the drive that does the delay according to the type of heads installed. In which case the same controller should work with both. I'm suspecting the problem is actually something completely different.
Jsut an Idea, but you may want to contact the guy that runs the channel "Obsolete Video". He mentioned that he rebuild video heads for his old reel to reel VCRs. Maybe he can help you fixing the drive heads of your Finch and Hawk drives.
My old job is still operational somewhat, I can ask if they have any parts for this setup. Send me a list of what to ask for. The ancient company has several mini computers, and several floors of old components.
I watched your bunny do the read, write and erase of its lunch.
My favorite comment so far!
Wouldn't 'erase' require the camera pointed at the 'output' end? I much prefer this angle though.
@@jasonhaman4670 I think that would qualify as emptying the recycle bin 🙃
If you don't mind, I'll pass on the cpu dump...
Came here for the main video, stayed after for the bunny's lunch source code rendering.
You can use a hair dryer to heat the board up to failure. When the failure shows up, use a can of freeze mist, one chip or component at a time, until it works. That will identify your thermally intermittent part.
David needs to read this comment. So I'm commenting here to try to boost it for you.
also commenting to push this comment, and when he says freeze mist he means the disposable cans for spraying dust off computers but turned upside down
Thanks for making the video. I worked for NCR Corp from 1978 to 2003. I have a lot of memories repairing those Halk drives. Head crashes were very common and hearing the heads screeching on the platter you can never forget! Nothing like walking into a office building with a 20 lb tool briefcase and a 20 lb oscilloscope was a distinctive sign you were the geek of the times. And yes under the suit coat was a pocket protector.🤓 PS: most head crashes were due to the micron filter being clogged.
You are so old you had a pocket protector, then realized it was uncool, without realizing they are cool again.
I am of the 486 vintage! And I can clearly recall that most of the people back then in most offices I have been to used to smoke, a lot 🤣 hence, most of the machines I scavenge from that era, have a certain yellow grimy patina that coated most of everything, and it was way worse on the ventilation side of things. Hence I can only imagine what these drives had to endure back then 😅
Only two 20lb items? Sheer luxury!! At DEC we also carried a 20lb briefcae full of microfiche and a reader!
*Hawk drives. They're all named after birds.
This takes me back. My first job in the late 1970's was as an engineer with a Wang computer dealer. For removable drive storage both Hawk and Phoenix drives could be attached. One of our jobs was to fix these drives when they went wrong - but back then you could order replacement parts! Our most common problem was when data errors were reported. This usually occurred either because the heads had drifted out of alignment or there had been a head crash. In either case a head alignment process had to be undertaken. This involved connecting the drive to a special diagnostic control unit, attaching a scope and carefully adjusting the head position until the scope showed the correct waveform whilst controlling the drive from the control unit. Over time you got a 'feel' for the alignment. Also I recall that the air filters had to be changed at regular intervals as they could get clogged (especially if they were in a smokey office environment which was common back then) and fail to remove dust particles properly which could cause a heads crash.
One of the features of the Phoenix drive was that it had several fixed platters - but depending upon which model was purchased depended upon how many of these platters could be used and hence the capacity of the unit. But the number of fixed platters that could be used was determined by links on the control board - the drive being the same for all capacities! One of our jobs when installing these systems was to configure these links to correspond to what had been ordered. Or if the customer had initially ordered a small drive and then paid for an 'upgrade' to a larger model we just adjusted the links and hey-presto the customer had a larger capacity drive
Wow - didn’t know you could download a larger hard drive that far back 😅
@@markmuir7338 Back in the 1970's you could get disk drives which took a 200Mb removable disk pack which had 10 platters giving 20 sides of 10Mb each. These were big beasts and if there were several connected (you could have up to 8) you could feel the vibration in the room when they in use. Head crashes were a nightmare!
Wang 2200?
@@robertlewis4216 Possible with the 2200 MVP,, but I used these 200Mb types with PDP-11s. It was more usual to have the 200Mb drives with the Wang VS computers. I used Hawk or Phoenix drives with Wang 2200 VP/MVP computers. Then Wang brought in sealed hard drives (I think 8" Winchester?). These tended to go out of alignment with use and you had to adjust them using a scope. You could tell if they were out of alignment as they just kept seeking and seeking and seeking which you could hear.
Amazing insight into the past. Love reading people's experiences from back when this stuff was new.
It's important to understand that "erase" is a misnomer, the read/write head by itself is perfectly capable of obliterating the old data and writing over it. But magnetic gaps like in a read/write head have "fringing fields", like when you look at a magnetic field with iron filings, the magnetic field lines leak out beyond the gap in the head. This is still true for the latest hard drives today.
The "erase" head simply blanks out a thin area on either side of the track so that it doesn't interfere with the next track over. Is that wasteful? Sure. That's why you have SMR recording on modern hard drives, they only erase one side so you can record closer together.
Ideally the function should have been called "guard banding", but we're stuck calling them "erase head".
So what's the difference? The timing of when the "erase" coil is powered up when writing. It's a very low-level function.
There shouldn't be such a great difference in performance. Why they make different types of heads, I think boils down to what was easier to manufacture. Straddle erase heads seem to have been replaced very early on with tunnel erase heads on floppy drives, for example, but the only change was in timing in the FDC.
Search for the Motorola AN917 "Reading and writing in floppy disk systems using Motorola integrated circuits", it's for floppy disks, but I think the ideas are the same. I won't put a link because the comment won't make it.
Looks like best gift we could possibly send to Usagi Labs is a nice big box of new/old stock pre-erase Hawk heads.
And some working controller cards.
SLO-mo cronch cam at the end was awesome ❤
The real reason cameras were invented!
Ex-Burroughs guy here. We used comparable drives on the very smallest machines, and my understanding is that straddle-erase is not actually to erase data (before writing) but to trim the somewhat marginal flux pattern laid down by the edge of the write head to improve reliability and potentially to allow more TPI (less inter-track crosstalk for a given separation). That might explain why the documents you were looking at showed the flux pattern differently: the illustration of the PE showed the written flux looking like a triangular wave while that of the SE trimmed the top and bottom (although the illustrator didn't quite understand what he was being asked to draw, so rounded it off). Don't know whether this will work, but /\/\/\ vs /-\_/-\_/-\
If the drive you've got similarly uses SE to increase density, there's also a possibility that the formulation of the oxide on the surface of the disc is different which might contribute to compatibility (or at least reliability) issues.
As a footnote, we were trained during the early eighties to use iso on a lint-free (wrapped around a ruler borrowed from the customer) when doing an on-site repair, then to flush any remaining impurities off the surface with a liberal amount of Freon. Perhaps fortunately, they'd stopped issuing Freon as a cost-cutting exercise...
Updated: I've got a very hazy recollection that one type of erase might have been for removable platters, and the other for fixed where (a) interchangeability wasn't an issue and (b) since the ring holding the platter was torqued down the overall dimensional accuracy was better and there was an incentive to try to increase the TPI.
Yes, either Kim-tech wipe replaced frequently or in a pinch coffee filters are relatively lint free. Always had a steel 6 inch scale in the pocket protector.
@@mikebarushok5361 We were still issued with packs of genuine lint-free cloths, together with the spring-pullers and link-benders needed by every electronics guy in the early 80s. And for those disks you needed more than a 6" ruler: clean while spinning and that edge is /aggressive/ :-)
My electronics professor raved about how good of a cleaner that Freon was.
@@button-puncher Presumably because it's easily-distilled to high purity but... heavens.
Out of curiosity, roughly what year was that? It would be interesting to know when attitudes changed.
@@MarkMLl_uk My prof was talking about it in the late 90's. The US made it's sale/production illegal in 1995.
It was supposedly contributing to the depletion of the ozone layer.
Considering that the ozone hole in the atmosphere is the same size as it was 30 years ago, it sounds more like the environmental "scientists" don't know what they are talking about. Yet again.
You've mentioned a few times that you're terrified of the Phoenix drive, but I forgot the reason why.
You are one step closer in understanding the system. That’s valuable information to have. Imagine if someone reaches out and says - “I have a hawk drive that doesn’t work with my system” and you discover that it’s a PE head drive and they need an SE head drive…
I get the idea that a controller card designed for SE can work with either type drive. SE requires separate erase and write passes, and PE will work fine when used that way. It's just PE cards can't work with SE drives because they do an optimized single erase+write pass, which can't work when both heads are in the same position.
I love old hard drives. Such beautiful machines.
Me too, that's my favorite part of retro computing!
@@UsagiElectric someone needs to figure out how to make more of those
It's so cool to see a hard drive operate on such a large scale. Not a tiny, sealed, monolithic block with just a connector on it.
@@monad_tcp As tinkering in one's home lab gets better over the decades, I wouldn't be surprised if people start making their own equipment and platters. After all, we have access to xray scanning equipment to reverse engineer heads and such now.
@@UsagiElectric Count me in too :-)
You seem like someone who would know. On the late seventies I had a friend who worked for a company which had a mini computer much like those you feature. After hours, he had permission to invite friends in for gaming. We played a game called "Orion III." It was a "Star Trek" like game where ship, planets and other visuals of the game were represented on screen by ascii characters. The amazing thing was... up to 16 people could play this game, in four teams of four. I remember the disk drive for the thing was huge; like a top-loading washing machine. There was a stack of platters in clear plastic holders... they would be lowered into the drive, then the plastic outer covering would be lifted out. The lid would be closed and the air pumped out before the disks were spun up. Have you heard of anything like that? I've been looking for the game specifically for a long time!
Anyone else amused that the heads have little faces? Pretty cute for having been through such a traumatic crash.
Yes, every single time I see one. I even started to wonder if one of the engineers thought about looping the wiring to put ears on either side of the head.
I love that you have become apart of how I unwind on Sundays.
Get home from church, have my artisan coffee, light up my cigar or pipe and enjoy some vintage computing. Thank You!
Hey there! It's been 40 years since i've worked on any of those old CDC drives and my memory isn't that great anymore so maybe i'm remembering this wrong but I seem to recall that the straddle erase head doesn't work like you think they do.. it is there to trim the sides of the written data to ensure the guard bands are preserved, you got a nice narrow track and this allowed you to get a slight increase in data density, they are enabled at the same time as the write head.
I recally a low and high TPI mode on these drives too and many machines of the time used a hard sectoring card that was adjustable via jumpers or switches, this drive might have different sectors or tpi to your other drives.
Head crashes were almost always caused by a clogged filter so make sure you stay on top of those, I doubt the originals are available anymore but you can probably fabricate something with a 99% .3 micron hepa style filter should you need to.
Anyhow best of luck with it all and apologies in advance if everything i wrote it totally inaccurate :)
This is the first video I've ever seen from you and I'd LOVE to see what's on this drive. There's just something about snooping around other people's long forgotten data from years if not decades ago that I just can't resist.
These drives used IBM 5440 disc packs, as did the first machine I ever programmed, an IBM, back in the 70s. The DEC RL drives also used these packs. They were known for their reliability and were usually rock solid. Nice seeing these things still spinning in Dave's garage
I know there was talk of recoating the platters, and possibly rewinding the heads, did anything ever come of that?
I've been thinking about that. Breaking taps has been doing silicon lithography, so I wonder if this is something that could be done today by "home" workshops.
There was an idea, but no direct plans, just wishes.
I've been wondering where the original manufacturing of platters took place and what machinery was used. It would be awesome to see the original machinery refurbed and creating new platters.
@@Nebulorum That was a great watch, I had not heard of Breaking Taps prior to your comment.
Looking at the design in the close-ups, unless they are soaked in some epoxy i can't get off, i should be able to rewind them just fine.
Hawk Tuah Drive
This is my first video I've encountered from this channel, and I am *heavily* intrigued by how this kind of tech almost makes enough sense to understand for someone like me who isn't an engineer, and the journey to keep it running is gonna keep me invested.
Thank you for taking us along! It is so much fun learning new things about old tech. I don't understand all of it, but I feel smart watching. 😁😁
Thanks for coming along on the ride!
I was lucky enough to be at VCFE when he was doing some of the work on the drive! Very happy to have gotten to watch part of this in person :3
I can understand why the Phoenix drive scares you. I can still feel the cold brick in my stomach when i got
a "system down" call and i knew thier primary drive was a Pheonix...
What makes the Phoenix drive so scary?
@@Intellistation6225 the emergency head retract, while staring intently at the scope at 2 in the morning with the customer needing system online at 5.
I love these drive videos! As a data center guy and vintage fan I get a kick out of the fact that these names "Hawk", "Phoenix" are still in use for server storage.
I remember seeing a very similar looking drive back in high school, just sitting in the back storage room of our tech department. The department was run by an older guy that used to work for some huge telecommunications company like Bell Canada if I remember correctly, pretty sure he was the one that donated it to the school. It was around the same size/shape as the Hawk drive in this video and also weighed an absolute ton, only it had three orange platters instead of one, and I think the frame had more of a golden/brass colour to it. Really cool to learn more about drives from this era and seeing one (more or less) in action, great video.
The weirdness of head differences hits again
It's wild to me to think that 99% of the drive can be identical and it might as well be a completely different drive as far as the controller card is concerned!
My reaction every time he gets a haircut.
@@UsagiElectric Terribly sorry but are you *sure* the straddle-erase needs a full revolution on CDC drives to overwrite data?
Do you happen to remember from where do you know that? (No links please - youtube doesn't like those)
I'm not knowledgeable in the subject and might be totally wrong but that's not how I understood the process.
I thought in straddle-erase the write coil overwrites data while erase coils erase the guard-band,
while with tunnel-erase heads the erasure happens a little ahead of time of writing
That is what the jumper is supposed to change - it should introduce a delay between erase and write
@@jwhite5008 That's something I'm curious about, was the jumper on the drive PCB set correctly? Maybe you could also scope the output from the read amp to see if the signal is even written.
@@Stoney3K Actually I'm more interested in oscilogram of what is actually *read* from the platter. I think the issue might be unrelated to the head type. There is quite a lot that happens between issuing the format command and reading stuff back, and any of it can go wrong to produce such a result. Inconsistent head positioning or read/write attenuation for example
See also my next comment
Your detective work, and comprehension, is inspiring.
Something that seamed overlooked, or perhaps forgotten, you didn't mention installing a StradelErase head controller card. Is that possible (two separate controller cards)?
Thank you so much!
Unfortunately, Centurion never made a straddle erase controller card, so we'd have to build one from scratch. But, since I already have two working Hawk drives with pre-erase heads, we'll instead shift focus to something else, and reserve the straddle erase Hawk for a different project.
I was thinking on the same lines, while looking at the schematics and wondering how hard would it be to modify the controller to use both types of heads (selectable of course) Shugart drives used this types of head, have to look at the schematics but I would assume the mods will have to be related to some sort of delay between the erase pulse and the write one.
@@UsagiElectric Someone (CDC?) made a RWE card set up for straddle-erase heads, or the heads themselves wouldn't exist. Whether said card would work in a Centurion is another matter. 🙂
My guess is that somewhere there is (or was) a PE-equipped drive plugged into a SE RWE board that writes at half the speed it's capable of.
Digital High Five back at ya!
Heck yeah!
Don McMillan Digital High 5, so 101 ?
wow that's both really cool and unfortunate!
also digital hi5 and yay for slo-mo bunnies!
High five!
I don't know how I got to your site and all I can offer you is a PDP, Trash 80 icy pole. Keeps up the fantastic work, my empirical data friend!
My First IBM PC had a whopping 15MB storage and i could only fill it up to 5MB with so much software available back then. Hard Drives were like Hard Currency.
My first IBM PC had two 360k diskette drives, so cower before me Emperor.
I was able to visit the LSSM in Pittsburgh last year and got the grand tour. It was one of the highlights of my visit to the states and can highly recommend this place. I even learned that I was wrong about a thing or two and since strive to do better.
this lens is great, the depth of field lenses distort everything
8:43 You absolutely can see a scratch on the top surface of the fixed platter. Bottom left corner of the screen.
I noticed this too. Just seeing that line around it that's visible in the glare, I thought "hmm looks crashed".
Quite a blast from the past seeing that technology.
I find it fascinating that you _like_ CDC drives. I used to operate a CDC Cyber 72-26... with an 808 drive attached. It was huge, and terrifying. It used a separate 1500psi hydraulic pump to drive the heads. Fortunately I got an offer to change jobs, and waved goodbye to that CDC forever.
Wait.. A *hydraulic* head stack servo?! That both sounds cool and oddly terrifying at the same time.
@@Alexis_du_60 It was mainly terrifying Alexis.
An 808 was tall - over 6 feet high. The platters were over 2 ft diameter, and there were a LOT of them. So that the heads did not droop as they were pushed towards the inner track, they rode a fixed steel bar that was about 3 inches diameter. So the huge mass of the head assembly did not cause the whole drive system to rock, they had two spindles, one on each side of the logic and head actuators. The two sides were driven in unison, in opposite directions.
*Everything* about the 808 was massive... and despite the power applied through that hydraulic ram, they were slow to seek, with what had to be the longest latency in the rotating data storage game.
So far I have not seen any reference to one on the web.
I don't know why exacly but I really enjoy these videos. Thank you for all your work to make them.
My mom and dad both worked for EDS for a good chunk of it's existence till it was bought out (funnily enough, they met when their two teams were having issues, and mom and dad were the two chosen to communicate between the teams). Our house is still is chock full of EDS whatsits; heck, I'm drinking out of an EDS mug right now!
So hearing that name REALLY snapped my attention back to the video, lol!
Really takes me back to my first few years at work. The MRI I maintained used a 11/750 for the scanner and a 11/730 for the standalone viewing console. Both had removable packs. Something was really satisfying handling those packs.
Good to see you;re using a TEk 465 scope.
RE: Fixed drive not writing. This reminds me of a customer of mine back in the 70's who had a removable pack Plessy drive. He was using this for archiving data. What he didn't realize was that the write protect indicator bulb was burnt out. The drive would accept a write command but would not indicate write fault. When he (we) figure this out, we examined his "most recent" archive, and the data on it was three years old! Lucky he didn't have to rely on an archive/backup. Check your write protect button and indicator bulb.
Am I the only one who sees some smiley faces when looking at these heads?
Definitely not the only one!
I see the faces of CYBERMEN when looking at those heads! YOU WILL ALL BE MADE LIKE US.
@@PCFixerthat sounds like vintage (Tomb of The) Cybermen to me... none of your new-fangled "Delete Delete Delete".... although, if it's a stradle erase head, should that be "Erase Write Erase"?
•_•
ꍓ
●⍘●
Well, the cyberman does delete your platter if it gets too close to it...
Back in the 80’s I had to get one of these CDC Hawk drives from one end of LA to the other, put it in the trunk of my Toyota Tercel,wound up with a dent pointing out from the sheetmetal of my trunk when the drive shifted around. Disk drive was fine.
Every time you talk about the EDS PC I am reminded of the TV show "Halt & Catch Fire". The story you tell of Centurion getting into the PC market is so much like the fictitious company Cardiff Electric in the show.
I dig those white, incandescent indicators on the drive. Quite pleasing.
Lights come on. Understaning emerges. Thank you. Very cool video.
Thanks! I learned so much about different head design in this one, it was quite fun!
I think one easy way to describe the difference between pre-/straddle-erase heads is the coils in pre-erase heads are arranged in-line with/parallel to the data tracks and the coils in the straddle-erase heads are arranged perpendicular to the data tracks.
These are beautiful machines, well worthy of preservation
I remember learning about the AMD 2900 series, and how you could define your own instruction set in the microcode, this was back in the mid 80s, at Polytechnic (now converted to and called University). We had a great lecturer who was very excited about his subject. I hadn't realised it was used in so many systems.
David, Keep making videos please.. Lots to learn. Lots of engineering. Thanks.
I used to work on some Honeywell Level 6 machines and they had Hawk drives. Fixing a head crash on the fixed drive was comical. They pulled out the bad platter, took out the heads. Sanded the heads with fine sandpaper and then washed them out with high percentage alcohol. Then the would put in a new platter, reinstall the heads and format the drive. That worked - most of the time.
Watching a voice coil actuator was always impressive 'back in the day'. But what what was really awesome was the hydraulic actuators on the IBM S360! It seemed to me they were faster than the voice coils.
I wonder if you will be able to find the appropriate hawk controller. A head rewind attempt would also worth the search of somebody which have the right tools ( and ideally knowledge). Amazing machines.
Many years ago when I was a student, we had a VAX, and I recall a time when I was in the computer center, and we heard this horrible noise coming from the disk cabinet. But we were totally baffled in that the system was still up and running and had apparently suffered no ill effects. We shut the system down as a precaution. The DEC guy came out to repair the hard drive, and we found that the motor shaft had sheared off where it went into the brake, and the horrible noise was the two ends of the broken shaft grinding against each other.
Gosh, my college has an Eclipse system just like that one in the museum, what a blast
Those drives greatly resemble the drives on Honeywell Level 6 Minicomputers from that time. I suspect they may be manufactured by a common OEM and then rebranded and sold by various other companies including Centurion. What that means is that there's a good change you can find parts like drive headswhich you seem to need from other stock and or drives if you can figure out who actually made the drives and who else used ones like yours for their equipment. Honeywell is still in business too so they may actually have some parts stored away in their parts stocks.
every hard drive I've worked with going back to the very early 70s (and those were designed in the early/mid 1960s) did flying erase/write in one pass. the erase gap was right in front of the write gap in the same head assembly, and both worked together.
Hot air rework station (for Surface Mount stuff) works well for precision heating of marginal components.
Plus it gives you a reason to buy one if you don't already have one. LOL!
I got a Quick 957DW a while back and it's really nice. I'm just a hobbyist. Didn't need anything more expensive.
Thank you for the bunny photage. Best part about watching your videos the bunny tax is paid.
Since you have an erase coil on either side of the write coil, with a straddle erase, you effectively erase before and after the location your are writing to. Which means that the data you are writing to the platter is erased after you write to it, no wonder you have corrupted data when you try to read it back. Since you have only four pins going to the head, presumably one pin for each coil with the fourth being a common, it would make sense to unpin the trailing erase coil, thereby converting the straddle erase into a pre-erase head. This might allow you to use this drive after all.
As much as I love these videos on these machines, I’m kinda nostalgic for the early tube days of the channel. It’s what brought me in, what you were doing was unique and fascinating.
I’d argue it’s time for a bit (lol) of tube computing videos.
We'll be getting back to that soon, I promise!
The paper tape reader for the 1-bit tube computer has gone through about three different design revisions over the past few months. I'm waiting on some new parts to arrive and then we'll start building prototypes and filming that. After UE-1 is finished, we're already working towards a design for UE-2. The reason there hasn't been any videos on that stuff in so long is because I'm trying to do a lot of the initial design work first, then get to work constructing and building it.
@@UsagiElectric excellent! Given what’s going on with Intel, I’d love to see people go revisit the 4004, perhaps using discreet logic chip, or, woooooo, transistors built into gates. I’d bet it could fit on a single 4x8 sheet of plywood using transistors.
Biggest recommendation is a 45.5 mm lens if you want crispness and depth in one package
Someone really needs to set up some virtual versions of these machines as teaching tools. It wasn’t until I started working with older more limited machines that I started truly understanding how computers work and how to write programs efficiently. Programming with extremely limited RAM and storage really forces you to think about cleaner more efficient ways of accomplishing tasks.
I think you are misunderstanding the straddle erase head. I think it means it straddles the full width of the track, a bit wider than the read write head. This is different to a tunnel erase head that has two thin strips that erase just the sides of the track. However, I don't understand why an erase head was needed for a digital drive as the write operation should overwrite any previous data. I think it was just to reduce noise from the edges of the track making head alignment less critical. I don't think any drives need two revolutions to do a write.
I found this info about floppy disk erase heads.
From the Siemens manual, page 3-4: "The read/write head also contains a tunnel-erase or straddle-erase electromagnet, the function of which is to erase the edges of the recorded track as the data is being written. The width of the track is narrowed to approximately 0.013 inch by this technique, to minimize the effect of data previously written on the track and possible crosstalk between tracks."
Discussion in the Siemens manual makes it clear that "tunnel erase" is one kind of head, and "straddle erase" is another kind of head; and that erase operation is concurrent with write. For instance pages 3-26 thru 3-29 describe the erase gating and logic during write: "The purpose of the auto erase feature is to provide the necessary turn-on delay between active WRITE and ERASE and the turn-off delay after WRITE goes inactive, but for tunnel-erase heads only. This is for option TE installed. Straddle-erase heads use option SE , which bypasses the delay circuits." A sketch of the tunnel-erased track shows that it measures .013 inches wide. The next document gives an explanation for why a delay is needed.
A CDC (Control Data) application note "5.25 inch FDD format considerations and controller compatibilities" examines 8-inch drive technology and standards. It refers specifically to tunnel erase vs. straddle erase in the introduction, saying "The head style and drive tolerances determine the minimum gap of the 5.25-inch FDD formats". The two erase heads as used on 8-inch floppy drives are described on page 7 as follows:
"Both head styles have as common parts a read/write gap and two erase gaps...The two erase gaps are used to erase guard bands on both sides of the data being written. These guard bands are necessary to to eliminate noise caused by old data that had been written slightly off track...A major difference between the two heads is the placement of the erase gaps....The erase gaps of the tunnel erase head are 36 mills behind the R/W gap whereas with the straddle erase head the gaps are on both sides of the R/W gap and extend approximately 11 mills behind it...Because the erase gaps of the tunnel erase head are so far from the write gap they must be turned on and off separately." Sketches of tracks for each head show that with the tunnel erase head, "used by IBM and most manufacturers", there is 6 mills of erase gap either side of the 13-mill track. With the straddle erase head "used by Shugart exclusively", each 6-mill erase gap is offset from the 13-mill track by 1-2 mills."
So both types of head erase just the edges of the track and it is done while writing in the middle. Straddle heads do overlap the write head length wise so they are turned on at the same time. Tunnel heads are behind the write head so needed a delayed signal. On a floppy drive there isn't a separate erase signal so the delay for tunel heads must be in the drive logic, not the controller.
Thank you for showing us all these beauties!
I remember back in my minicomputer days working on Data General equipment exclusively. DG used Phoenix drives I believe. As memory serves they were 10 MB per platter with 20 MB total (10 fixed and 10 removeable). We also had some much older Diablo 33 drives that were 5MB removable only but they were being phased out in favor of the higher capacity drives. There also were some washing machine sized drives with stacks of removable disks that I think were 80 or 120 MB (can't remember). Those were also much older but still in use back in the 1970's. I was never aware of the head differences. Quite interesting!
Need somebody out there with a watchmaker's precision to dissect some bad heads and come up with a way to make new ones or repair the old ones, there's certainly going to be a market for it!
We used to use medical "tube gauze" on a tongue depressor with 99 % isoprophyl to clean disk heads.
We nowadays take hard drives for granted, they're even being seen more and more like an obsolete technology with the advancements of solid-state storage, but it's astonishing if you think to all the R&D magnetic storage technology had to go thru to become the rather normal thing it is today.
How accessible are the coils on those heads? I have to wonder how feasible it would be to rewind the coils yourself.
That is definitely something we're going to tackle in the future!
David, since the badly crashed HAWK head was trash as far as you are/were concerned, why not take a no-risk chance at repairing or at least disassembling it under a microscope to better understand how it was built? You've got nothing to lose! I bought a stereo-microscope in order to attempt repairing a known-failed tape read (or write?) head for a DECtape drive. My friend had another head, so he swapped them out and sent me the bad one in the off-chance that I could get lucky trying to repair it. I need to re-start _trying_ to repair it for him!
You should put a scope on the head signals to verify the write pulses get to the heads. The writes should be causing flux reversals no matter what. You could probably trigger on the sector pulses and get continuous view of a single sector, a bit like you did with the timing track on the Bendix drum. Then try some writes and see what happens. Also maybe try the same but disconnect the erase coil. Lastly check the pinouts? Maybe your SE heads are different.
I'm fairly sure you're wrong about it using two passes to write a sector with the straddle erase head. The data itself doesn't need erasing -- the data head erases the old data when it writes the new data. The erase heads are only there in case there's a misalignment between the old and new data tracks, to remove any spillover. Erasing and writing is still a single operation.
From what I've read about this, the only difference should be that the pre-erase method might need a short delay between turning on the erase and write heads, because of the separation between them, whereas the straddle erase method would not need this delay because the heads are in line.
Since your controller board seems to be telling the drive to turn on data and erase together, it would seem that any such delay, if required, must be implemented somewhere in the drive itself, and the controller doesn't need to know about it.
So I suspect your problem isn't caused by the pre-erase vs. straddle-erase issue, there must be something else wrong.
Back in the day I seem to recall that main frame (ICL IBM etc) hard disks used significant air/vacuum filtration since the heads literally flew over the platter. Whilst a human hair would be pushed out of the way a smoke particle could cause a head crash.
This may be an apocryphal story but I'm reminded of an issue, in Holland I believe, where for some reason a head crash occurred. Since work had to go on the removeable disk pack was tried in another reader. That crashed too. Now there are 2 readers destroyed. Nevertheless some bright spark tried another disk pack in the original reader with obvious results. Fortunately somebody with sense halted operations and called in the gurus to fix the fundamental issue.
5 1/4 inch disks held in the same hand as a cup of coffee can produce a similar effect. I know I watched it and had to sort it. The look on my boss' face when I took a pair of scissors to his precious disks will not be forgotten!
I had no idea there was such a big community dedicated to making working fallout terminals!!!
I had a strange idea: perhaps the heads coils could electrically be protected by adding a inline fuse. A small board could be made with a surface-mount fuse, which could be put between the head and board that reads the head. It the board goes, the head may be protected. Perhaps a few Zener diodes could clamp the voltage, a bit higher than its working voltage, too.
Ah! You are obviously a Pokemon fan! Go team Rocket!
Musashi and Kojiro - the real heroes!
@@UsagiElectric Team Rocket represent. They're always there for each other and they don't let defeat stop them trying again. Best role models
I haven't watched Pokémon since middle school, but I recognised that R immediately. Next episode I hope he'll put on that fetching cropped jacket they wore
I was wondering what "R" signified.
would be awesome if repro parts were made one day.
Might consider a stethoscope to listen for any bad noises coming from the drives. Would amplify and pinpoint them beyond what the unaided ear could hear.
I wonder if you could get in touch with Lumafield to get the failed heads scanned. They did such collaboration with other channels so seems worth a try
19:53 Team Rocket, YEAH!
That servo control board is going to be interesting to fix. I'm betting those cans are op amps, and i counted 10 of them. So any one of those op amps (if that's indeed what they are) could cause a failure. I'd bet good money that you have a couple of "instrument amps" for the reference and feedback signals, an error amp. The error amp would feed into probably at least a proportional amp and an integral amp (may even have a differential amp, but hose are tricky to get right). Then a summing amp to sum up the control signals (from the PID amps), then output amps to actually drive the voice coil.
And this is ALL analog, so good luck with that! Plus, there's no guarantee those op amps are even available any more. Sure, a new servo board could be engineered, but the cost would be eye watering. Unless someone just decided to do it as a fun project. ^-^
18:45 This makes me wonder why they made the removable packs blue rather than clear. Checking for signs of a crash seems like a common enough thing to do, and noticing damage on the platter before inserting it could save heads. All of this would be much more immediately noticeable if it was clear or had a clear window.
@UsagiElectric
Thank you for sharing your adventures with us!
Keep up the good work!
Is it possible to find someone who can rewind the coils on the heads that have blown coils? I know the wire is extreamly tiny, but there has to be a way to repair those heads.
Love a good Hawk too
I forget how much stuff you've picked up along the way!
This is so cool! I love old computer science and stuff. How do you even manage to get these!? (I never saw this channel until now)
The 120fps is neat, but I'd still like to see you do a collab with the slo-mo guys, with some stupid-high framerate capture of that chain printer in operation. My brain still refuses to believe that it's method of operation is a thing that can actually work in the real world.
2:00 Does the roadster in matching colours come with it?
When all heads fail: is there any documentation of how the head are designed and/or made?
If you it should be doable to recrate them
Otherwise once migt be able to disassamble an non-working head trying to reverse engeneer them
Same spiel for the servo cards
I know, i know it is a long and tedious project but we have come so far already
As seen at 27:44 the head mainly consists out of 2 transformers. And this is honestly how even a lot of modern hard drives are made these days with 20 TB drives as well. (except I think modern heads are MEMEs fabricated, since that is way easier...)
But yes, one can sit under a microscope and hand wire a new head. Just need very steady hands and plenty of patience.
How these heads were manufactured back in the day is a good question. I would not be surprised if they were manually wound by hand. Since that is how a lot of other things were made back in the 60's. (Magnetic core memory for an example were oftentimes manually threaded, a laborious task requiring a steady hand and plenty of patience.)
Ever thought of selling small centurion compatible kit computers using new chip kits?
I absolutely want to, that's just a new, uncharted avenue for me that I'm not quite sure how to run down. We'll figure it out eventually though.
@@UsagiElectric well if you decide to go with a bus card similar to the og I always thought it would be cool to use Sega Genesis 64 pin cartridge connector or a SNES cart connector for a computer like that because unless you want to make exact clones it's ok to be different if its still compatible
A Micro-ATX Centurion Motherboard! What a dream that would be! Similar to the Monotech NuXT except it's a full-Centurian Computer rather than an IBM PC!
As long as it has a thermal printer, I'm keen.
Peripherals are the one thing people always forget about in vintage tech.
They were the core part of what made them worth buying.
Put it on the 11/44. Then maybe you could read RL02 packs that are around here and there.
Really fascinating!
This video was quite interesting but as soon as he said that video isn't about the Phoenix drive I was immediately like "aww, maaaaan".
I have found some discussion regarding the head configuration on the larger floppy drives. The straddle configuration just trims the written track left and right to create some security gap to the neighbour tracks and to erase potential remains from an old track that can be left over due to slight positioning errors. Trimming the track can happen simultaneously or after writing, so these additional heads can also be behind the write head. From what I understand erasing and writing is still done simultaneously, but the timing of the erase gate must be adjusted in relation to the write gate according to the head configuration which is irrelevant on floppy drives as this is handled internally.
How is this implemented on the hawk drive? Are both gates exposed on the interface to the controller card?
5 MBytes - wow... That's like my average .docx file.... My first computer was a TI994/A... And I loved it...
That's more of a condemnation of docx and the company that inventeded it than a shade on this drive.
@@liquidsonly Yes,... no-a-days, programmers just add libraries, and code, no thought of how efficient you need to be... We definitely lost some skillz over the years... but we have also gained in amount of data you can process... I still love them old early 80's feelings..
That's 5 million ASCII characters without compression. That's a lot of text to type. Of course if you add images it will bloat up the document quickly.
@@OogobukMy COBOL object code couldn’t exceed 64k. Not a prob since all input was from 80 x 24, output was 132 chars.
After seeing the differences between Pre-Erase and Straddle-Erase, it looks like the biggest problem is one of timing. The pre-erase head needs to have the erase head powered up for one "bit" time-length before the bit is actually written to the drive, while the straddle-erase can power up the erase head and the write head at the same time as writing the bit. There's no need to pre-erase the bit since writing the same bit to the same place won't change the magnetic field in that position, and writing the opposite bit to that location should just overwrite the bit which used to be there.
It looks like the straddle erase head is more mechanically complicated than the pre-erase head, which is probably why straddle erase came later, but it should be easier to interface to it due to not having to juggle the timing so that the erase head wipes a bit followed by the write head writing to the same bit as you need to do in order to use pre-erase heads.
Edit: Well, if they're powering both the erase head and the write head up at the same time, that means there must be some wasted space at the start and end of each sector when using pre-erase. That complicates things even more.
There might be circuitry inside the drive that does the delay according to the type of heads installed. In which case the same controller should work with both. I'm suspecting the problem is actually something completely different.
Jsut an Idea, but you may want to contact the guy that runs the channel "Obsolete Video". He mentioned that he rebuild video heads for his old reel to reel VCRs. Maybe he can help you fixing the drive heads of your Finch and Hawk drives.
i want one of these in my house or man cave just because that would be one hell if a toy to mess around with
Nice job 😊
My old job is still operational somewhat, I can ask if they have any parts for this setup.
Send me a list of what to ask for. The ancient company has several mini computers, and several floors of old components.
Sunday morning == Usagi!