Using a NOP Generator to help fix a dead 1541C drive (Bonus Track 1 Sensor demo)
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- เผยแพร่เมื่อ 3 มิ.ย. 2024
- Time for another Commodore 1541 disk drive repair. This time it's a 1541C, the last large 1541 drive made. This drive sports the Newtronics mechanism with Track 1 (aka Track 0) sensor which must be enabled to work. I use a NOP generator to help fix this drive and explain how these work.
--- Video Links
More information on the NOP generator for the 6502 and Z80 including how to make one:
• 8 bit troubleshooting ...
8-Bit Guy's Commodore Disk Drive Video:
• Commodore History Part...
C64C Repair and PAL Modification video:
• Commodore 64c Repair a...
First Commodore 1541 Repair Video:
• Fixing a Commodore 154...
ROM images:
unusedino.de/ec64/technical2.html
6502 Reset Vector Information:
www.pagetable.com/?p=410
Programming the 6502: (Book)
archive.org/details/Programmi...
1541C drive donated by Geek With Social Skills:
/ geekwithsocialskills
--- Tools
Deoxit D5:
store.caig.com/s.nl/it.A/id.16...
Jonard Tools EX-2 Chip Extractor:
www.jonard.com/Products/EX-2-...
Wiha Chip Lifter:
www.wihatools.com/precision-c...
Elenco Electronics LP-560 Logic Probe:
www.amazon.com/Elenco-Electro...
Hakko FR301 Desoldering Iron:
www.amazon.com/American-HAKKO...
Rigol DS1054Z Four Channel Oscilloscope:
www.rigolna.com/products/digi...
Head Worn Magnifying Goggles / Dual Lens Flip-In Head Magnifier:
www.amazon.com/SE-Illuminated...
TL866II Plus Chip Tester and EPROM programmer: (The MiniPro)
www.aliexpress.com/item/33000...
TS100 Soldering Iron:
www.ebay.com/itm/TS100-65W-MI...
EEVBlog 121GW Multimeter:
www.eevblog.com/product/121gw/
DSLogic Basic Logic Analyzer:
www.ebay.com/itm/USB-Logic-DS...
Magnetic Screw Holder: (also on eBay and Amazon)
www.harborfreight.com/4-inch-...
Universal ZIP sockets: (clones, used on my ZIF-64 test machine)
www.ebay.com/itm/14-16-18-20-...
RetroTink 2X Upconverter: (to hook up something like a C64 to HDMI)
www.retrotink.com/
Plato (Clone) Side Cutters: (order five)
www.ebay.com/itm/1-2-5-10PCS-...
Heat Sinks:
www.aliexpress.com/item/32537...
Little squeezy bottles: (available elsewhere too)
www.amazon.com/Precision-Appl...
--- Links
My GitHub repository:
github.com/misterblack1?tab=r...
Commodore Computer Club / Vancouver, WA - Portland, OR - PDX Commodore Users Group
www.commodorecomputerclub.com/
--- C64 Stuff
JaffyDOS:
blog.worldofjani.com/?p=3544
C64 Test Harness I use:
• Building a Commodore 6...
C64 Homebrew cartridge PCB: (used for the DeadTest / Diag Cart I use)
www.ebay.com/itm/Commodore-64...
EasyFlash 3 Multi-Cart:
store.go4retro.com/easyflash-3/
--- Instructional videos
My video on damage-free chip removal:
• How to remove chips wi...
--- Music
Intro music by:
Nathan Divino
@itsnathandivino
Outro Music:
Abyss by | e s c p | escp-music.bandcamp.com
Music promoted by www.free-stock-music.com
Attribution 4.0 International (CC BY 4.0)
creativecommons.org/licenses/... - วิทยาศาสตร์และเทคโนโลยี
I wish school made learning as fun as this channel.
Ask Adrian to adopt you and then get home-schooled.
Would have loved having a teacher just like him.
Some schools teach this. Not all, just some, and I do mean at least one.
I agree. Adrian is detailed and easy to understand. I really enjoy these videos he puts out. Thanks Adrian. I look forward to more of your vids.
Hell or as easy to understand/replicate if you wanted to
I'm a simple man.
I see the notification that Adrian uploaded a video, and I click it.
I'm 16, I have no business watching these types of videos, the oldest computer I've ever used ran some Pentium on Windows XP, but this is some of the most interesting content I've watched in ages! You won't lose my sub anytime soon haha.
Thanks! We need more younger people into this whole computer history thing. The troubleshooting skills you have to learn are invaluable in life.
I equate these old consumer computers to cars in the 50’s and 60’s where one could look under the hood and actually understand what was happening from the fuel line to the battery (and no, the fuel lines don’t go to the battery), to the carburetor and spark plugs... Can’t do that with cars or computers today.
You're not alone friend. I wasn't around for this era but there's this raw energy and excitement for the future that these old machines whisper to me. Plus understanding these old hulks is an easy way to get good at modern low level stuff. It's basically the same except nowadays it's harder to see things laid out in front of you.
And you totally have business watching these videos. Were more 16 year olds as curious as you. Speaking of, check out curiousmarc here on YT. You may like their Apollo guidance computer stuff.
Young people: Get real hardware and use it before it’s too late. These old computers are something special.
@@adriansdigitalbasement I'm 14 and fascinated by anything involving electronics made before 2005
Your channel is one of the best if not the best retro and instructable channel that I watch. I have repaired all sorts of vintage equipments thanks to your videos. Sorry I haven't been able to comment to your videos frequently because my nvidia shield does not have this feature. Keep this excellent work.
In the video, Rodney Zak's book on 6502 programming is recommended. That book is very dated and doesn't cover the 65C02 and 65C816. A more-current book is "Programming the 65816, Including the 6502, 65C02, and 65802" by David Eyes and Ron Lichty. It's available online and is well-written.
You hit your $FFFF subscriber milestone!
I was hoping to get a screenshot! I missed it.
Luckily it didnt overflow! xD
Bad 6502s are more common than they get credit for... My first 1541 had a bad 6502 as well, diagnosed similarly, but since it was socketed, I suspected the CPU much earlier after a scope showed weird bus behavior. I bought a "new" 6502 from Jameco and it worked a treat. Starting to think 6502 ought to be more suspect in the diagnostic of bad drives ;)
I wonder if it is the way they are being handled. Back then static was a big issue. Wrist straps were SOP always. Later years they were done away with because diodes were added in the chips to deal with the HV static discharges. Now they are in everything and wrist straps are only a part of history.
On the old 1541 you can put a small strip of gaffers/duct tape at the rear of the head to mute head knock.
My drive still has it now, 30+ years later. =)
PS. Nice video Adrian!
Now that is some genius trouble-shooting. Totally out of the box and I love it!
I love the 1541C drive, especially after you enable the sensor. (Goodbye head knock!). I did on mine more than 30 years ago and never ran into any issues that I recall. I still use it today. But if you do come across any further information other than what was known at the time as "compatibility issues" please let us know.
I recently acquired a mint 1541C that has the track zero sensor. I have been vacillating about cutting the jumper and so far haven't done it, but 30 years is a pretty good test period.
@@jasongins Go for it. 😃It's still my main drive that I use. Besides if you find something you don't like you can always reverse it. Or you can install a switch so you can enable it or disable it at will. To this day I still don't know what "Compatibility Problems" would have caused them to disable it from the factory. Afterall, they used the sensor on the 1571 and while that is not 100% compatible, even in 1541 emulation mode, it still works fine with most software.
i wish this youtube channel existed during my college days :)
I feel like Adrian's really levelled up his game lately :-)
BTW This goes so well together with all the Ben Eater videos I've been binging lately!
I've been watching Ben Eater too, making his 6502 computer. Really good stuff.
Some people are natural geniuses. Adrian is one of those people and formats his NOP instructions in an interesting manner to boot! Well done. Entertaining and informative. So next time, try replacing the 6502 before anything else. ;)
I haven't lived in the Commodore computer family, so watching all these videos from Adrian and other Commodore lovers is making me more and more excited about getting into this genre. I always lived in the Apple II/IBM PC communities, so learning about these is a real treat.
What's a Gatorade chip? ;)
Hell, with their habits of naming chips in those days ya never know!
katie_incredible When a normal chip fails, Magic Smoke comes out. When a Gatorade chip fails, a sweet green liquid comes out. Simple. 🤓
It's not a "Gatorade" chip. It's a Gate Array, which simply condenses a complex network of logic gates into a single chip. No sports drinks are released in the operation of that chip, even if it fails.
I know that was a joke; I just wanted to help avoid misinforming anyone who doesn't understand tech and reads these comments (admittedly a small minority).
@@andrewsprojectsinnovations6352 NO SHIT? As God is my witness I thought turkeys could fly!
@@TheRealBrockRoberts Really?!?!?!? I thought it was Gator Aids
Was listening to the audio of this while doing something else and every time he said it my brain automatically translated Gate Array to Gatorade.
Actually it starts counting at 0xEAEA since that’s the contents of the reset vector.
Did I learn anything from this video? NOPE, I mean NOP; actually YES..!
OMG, that 6502 book was my bible in the 80s, Now I have to find a copy!
I added heat sink's to both my drives on all the chips and a cooling fan on one of them and have not had any problems running 4 years without a chip failure and they get used a lot.
i have 2 drives aside that have the same problem as well that i have to fix one day. Now i know what the problem is. thanks Adrian
You noped the hell out of that 6502
that was a leftist 6502
this channel needs more subs. why? because its not mindless nonsense like most content on youtube. you leave politics out and dont rely on click-bait. plus, you seem like a genuine person. kind of like someone i could sit down with, have a beer with and discuss old school pc stuff with....
on a personal side note, you remind me alot of an uncle of mine. seriously. he got me into pc stuff growing up and because of him, i became who i am today with the knowledge i have. also, the epic memories of things like when the internet was "released" as we know it in the 90's or standing in line waiting to grab various new Windows releases from "The Good Guys"....
I never would have imagined a test rig like that to test the lines like that. Holy smokes, that gives me a whole new angle to attack these dead 1541's I've been using as a bookend all these years. You sir are a wizard! Rock on!
@ungratefulmetalpansy Commodore, for all their innovation, was notorious for using shoddy parts and cutting a lot of corners. I'm just excited to hear there is a means to actually check the data lines, as it could save some old hardware.
Thanks for your education break. First time I'd heard that great idea for testing the select lines.
Amazing! I remember the times when a computer debug meant both hw and sw (assembler).... Judging only by the small preview picture i thought it was an arduino board. Boy was i wrong and excited to see the brute hw way of generating an instruction for the procesor to load..... AMAZING!!!!
The NOP gen was genious really .... you can inpsect fully decoded spaces.
Adrian you are so cheap. Couldn’t spare some sockets just in case it didn’t work? Love it because I am cheap too! Keep up the good work! Love the videos and eagerly awaiting the next one.
i love watching ur vids when not at work on all this old stuff i grew up with so relaxing to see them alive again and strong as old boots ty Adrian u made my day :D
Love your 6502/digital logic troubleshooting sessions. My favorite digital troubleshooting channel!
Hi Adrian, just as a hint: one should NOT put a socket with the machined pins into another socket. The pins are thicker than normal IC pins and widen the contact fingers, which can lead to premature failure of the socket.
It's quite interesting that this drive comes originally with a 6502 CPU that is a 2 MHz variant. The letter 'A' after 6502 indicates that it is 2 MHz. I was really hoping that the replaced CPU would be a 1MHz 6502 because you masured the clock and it is actually working at 1 MHz. I wish your 1MHz spare worked.
Awesome to see you go through the potential issues.
The legendary reliability (or lack of) of MOS Technology devices, anyway good troubleshoot video.
Awesome troubleshooting, as usual!!
Learned quite a bit about 6502’s in the process!
Thanks Adrian!!
Thank you for another excellent video. This is almost like watching a thriller, or crime drama like NCIS or CSI , except better because it's real, you're solving the case yourself, and using cool hacks which are techniques i can use, tools I can actually build in my workshop and use. practical, informative, clearly explained.. A joy. thank you again.
Some days I feel as if my life is directed by a NOP machine. :3
I've around 7 or 8 of these drives and on all drives i had to cut the J3 for the track sensor. Did this 1 or 2 years ago. Great videos adrian, thanks for it.
You have certainly elevated your skills lately, or have been holding back before. Certainly more valuable information than others that just think "retrobriting" is restoring, instead of actually saving machines like yourself. Great video.
Unless I'm messing with RF stuff, I like to have my signal ground on a separate probe. They're all tied together inside the scope, so if one's connected - they all are. Having it connected separately keeps it out of the way when I'm moving the probe about and doesn't risk coming loose and shorting something.
Great video. I especially liked the idea of using the NOP hardware mod you created. I'm going to build one and keep it in my toolbox. So easy to make.
Thanks for taking the time to explain this.😁
Loved the NOP video !!!! you have a knack for explaining things in a way even dummies like myself can grasp
Great video! It went sufficently into depth and I could learn some things.
That NOP generator is a smart thing. I will keep it in mind :-)
I'm really loving your recent videos, very informative and creative. I never have seen or experienced a faulty CPU before. Maybe because I work with newer computers. You need to have a logic analyzer, it will make your life easier and will provide a wealth of information for the kind of debugging you do.
Thanks for the detailed NOP explanation!
Newer chips have static protection built in while older ones do not.
Now that was freaky: We both have The 8-Bit Guy's Commodore 128 restoration video as our first recommended video! :O But not surprising as that video was what got me back into Commodore stuff so it's all good. Anyway, great video as always. I love Commodore 8-bit stuff.
Love your videos, learning a lot of commodore repair tips including electronics. Thank you :)
thank you for sharing your bug hunt! i can't imagine how much additional effort you must have spent in making such an educational video from it.
In other words: even with half the effort it would have phantastic. but for this i have no adequate words. Thanks again, please continue this work.
BTW: 17:50 this book teached probably most of us 6502, but honestly i do not not know during which house move i lost my copy. nice to learn that's available online for free.
Time to order a few spare 6502's. Never hurts to have new ones around. Keep them in antistat foam as well.
This was a wery good and easy to get explanation, thank You for sharing!
I was really hoping it was something other than the 6502 again. I recently bought my third 1541 disk drive, and it's the only thing left in my ever growing collection that doesn't work. It has the same solid red LED and perpetual spin. I did a full exchange of socketed chips (all of the main chips were socketed) between the dead drive and one of my working drives. The working drive still works, and the dead drive is still dead. I checked all of the voltage rails and got exactly what is expected everywhere I looked. I definitely learned a lot about these drives watching this video and your last 1541 video. I was just hoping one of the drives would've mirrored mine lol.
Every time you say "gate array," my brain hears "Gatorade." 😂
Great video. Love these in depth technical troubleshooting ones
Oh, this is great, thanks, Adrian! I just de-banged my 1541C. And I ordered some new power supplies to make it cool and light - now that I know how to^^.
The pins are high and so am i.
Love your content AB
The section on the NOP generator deserves to be a separate video in it's own right.
Thanks I should include a link to jump right to that section!
I like your videos a lot. They are very educative. Have your ever considered wearing an esd wrist strap? Some of the damage could be done by an esd discharge. Especially CPU's and RAM's can be sensitive to that.
Yup. I was just thinking how those were SOP for opening anything back then. Chips would break from HV static discharge if you just looked at them wrong. It is just taken for granted now that chips have that protection built into them.
Great video again, thanks! Also thanks for the minipro highlight👍 just bought one and good to see some real hands-on.
I've been looking for a video on diagnosing 6502 CPUs! Excellent job!
They should make it so you have to comment to give a thumb down so you can see why they dislike. This video has so much useful information it beats my why anyone would dislike it unless they are just trolls who dislike anything they do not understand.
My brain hurts watching this. Fascinating to watch even though I'm barely keeping up
Loved video . A real trip down nostalgia lane. Thanks a lot . made my day.
Awesome video and awesome hardware debugging technique!
Best video you’ve ever done. This is what I want to see. Thank you!
Amazing troubleshooting. I programmed tons of 6502 in the day on my Vic 20 and apple 2e with an apple cat modem.
Adrian...You and your videos are awesome..Thankyou for the entertainment.
So sad you don't live in the Swiss mountains - that would make for great electronics/software meetups! Great video!
Wow! Nice! A man who knows , what he is doing and is able to explain it.
What a thoroughly enlightening video! Well done Adrian :)
Excellent video. I was expecting to see the add-bus pins flipping at different freq with the nop generator AND the good CPU :)
I love the learning but the noop was way over my head. But I'm new to this so guess that expected super cool to watch. I love seeing the Oscope and seeing how you use it to make since out of the data
Really appreciate the debugging info!
Excellent work, dare I say best one yet. My brain hurts a little but in a good way. Think I'll need another watch to absorb all this information
Nice work Adrian. You and 8 Bit Guy make me want to go out there and buy a Commodore 64 and 1541 Drive ! :) I was into Apple ]['s from 1980 on, but my brother got a Commodore 64 in 1983 ... great machines, great times.
Twilight Zone Narrator: "Little did Adrian know that this was a sign of the beginning of the 2020 and 2021 world wide death of the 6502"
(ominous music plays)
Great video, thanks for sharing Adrian. I just scored myself one of these drives and is fully functional. I noticed it knocks the head though so might check out J3. Cheers :)
WOW! Now that is some awesome troubleshooting.
Adrian, I love your channel, you're the best brother!
dude this was really an awesome video. probably your best. definitely had a vibe like a '8 bit show and tell' or a 'ben eater' video. thnx a lot
Continuing to be surprised what great stuff some people share... A brute force hardware NOP generator... So awesome low level I can't get imagine any lower...
Great work, love the NOP 64K ROM :)
One of the things you can look at when you are checking the address lines on a running 6502 is that A0 should be changing constantly at a frequency varying from about half the clock rate to the clock rate as it reads and executes instructions. It would be only very unusual code that leaves A0 either low or high for more than a few cycles.
And when using a NOP generator you should see A0 cycling at exactly half the clock frequency, 500 kHz on a CPU clocked at 1 MHz. (The NOP is two cycles, so each address will be read twice before incrementing to the next address.) Every address line above that should be cycling at half the rate of the previous one: 250 kHz for A1, 125 kHz for A2, etc. You can just walk your scope up the address lines (increasing the horizontal time base as necessary as you move up) with the frequency counter or channel frequency measurement turned on so you can see the frequency halving with each step. It's a good quick way to check that all the address lines are working properly.
Awesome explanation of the NOP generator! That’s a great tool to have in certain situations.
I’m wondering if you could build one into a 40-pin “DIP clip” connector that hooks right over the CPU. You wouldn’t have to desolder anything, and you get convenient pins for scope probe hooks, too.
Who could down vote this? Amazing vid as always!
EA of course- tired of people NOP- ing them.
"You want our latest, greatest revenue generat.. er, I mean *game*?"
"NOPE!"
Hello Adrian after checking the address running within the NOP Eprom so you must check also that the 6502 is not in Reset. If the Reset is down the addresses are also not counting. Best Regards Volker from Vienna
That's really ingenious ... I'll make sure to have one of those at hand if I ever get back into C64 repairs.
On a sidenote: a friend of mine was involved in the initial SID reverse engineering effort which included scanning the silicon of the chips ... his verdict (as someone with a massive knowledge in that field): "it's a wonder those chips still work after all those years, if you extrapolate how bad the manufacturing quality originally was to begin with" (silicon supposedly is 'bubbly' as hell). I guess it's no wonder some Commodore chips have failure rates near 50% by now (PLA, MOS TTLs, TED/7501, some 6502s to name a few)
Incredibly good video Adrian. A pity not seeing the NOP data & bus signals with the good CPU. Congrats for such a good job!
When you said they call it the 'b-revision' I was just noticing that it says 'REV A' on the PCB :P
Learned a lot on this Adrian, thanks 🙏
The computer I had back then was an Oric Atmos. Its CPU was a 6052. So basicaly that drive used almost an entire Oric just to spin the floppy of the C64... Amazing.
There is no floppy controller chip in the 1541, all of the processing is done in software. This makes the 1541 an extremely flexible drive, you have very low level control to the disk; some games went as far that they used custom low level disk formats for copy protection.
Thanks for another great video! I'd like to see the Oscilloscopes output of a working processor with that NOP-Adaptor. Maybe you can show this in another video 😉
You could add a 74244 to the NOP generator to honor the /CE signal.
Wow! I just recognized those Supra and PPI modems on the Sony monitor. I had a brief flashback moment.
Yeah those are for an upcoming project :-)
fun fact. use a criss-cross wired dpdt switch on the red and black wires on the drive motor to be able to read the reverse side of 1571 formatted disks
Excellent repair video!
NOP generator... inspired. Love it!
I feel like you could do ASMR. Like Commadore 64 ASMR. Cause your voice is so nice ♥️
When your NOP-Generator has problems with cross-talk or the resistor solution is not applicable and CS(chip-select) has to be respected:
Use a SN74LS24x 3-state octal buffer like the SN74LS244 with CS wired to 1G+2G.
Some simple pattern generation or address framing can also be done this way utilizing the A-Channel-Inputs.
BTW: An EPROM is a wonderful pattern generator. Fill it with EA and you know what?:)
SRAMS and EPROMS are commonly pin compatible. So what it's doing is running through a program routine on the SRAM and then a verify. You can "program" SRAMS but they lose everything on power loss. The only problem is you don't want to use high voltage programming or you'll probably damage them.
Never a bad video on ADB !
Only when he is trashing RF shields...
Are we calling it ADB now? Shame that ADB isn't a 6502 opcode, nearly though, there is ADC (add with carry).
Very interesting 🧐 thanks for sharing
This makes me want to get out my 1541 and finally repair the track 1 sensor issues it is having. Although the sensor is present, the drive will always ram the heads into the metal, producing the machine gun sound.
Edit: And you know what, I did, and it finally can use its sensor to prevent further wear to the mechanism. Thanks a bunch!
Nice to know some diagnostic tricks! ;-)
Greetings, Doktor64!