IBM had to change the power switch from red to white because of a government regulation that red buttons and switches could only be used for an emergency stop/shutoff function. That's also why the red reset button on Tandy computers changed from red to white around the same time (circa 1990).
Likely not 100% accurate and kind on BS side. Power strip have red buttons, plenty other appliances on/off switch was, are and will be red, record buttons are red. Someone took few line from multi-tome/page regulation and twisted interesting ways for some purpose and/or just was incompetent. Bright Red and Green usage are regulated on railways (direct sight of locomotive operator and stuff), red brick house and green pain not banded and plentiful around railways.
Well that was a trip down memory lane LOL. I remember these; I worked for a company in London around 1993 that had a ton of Model 50's that they wanted upgraded to be capable of running Windows 3.1. The 286 wasn't going to cut it and they didn't want to splash out the budget for new 386 or 486 PC's... so I and my team were tasked with installing these exact CPU upgrades into their Model 50's... I personally must've installed 15-20 of them. They worked... they definitely weren't as fast as a true 486 mostly because the RAM was still running at 286 speeds, but they provided a relatively cost effective way of extending the lifespan of these Model 50's they had already and performed on par or slightly better than my PC which was a newer 55 Model 386. The badge was shipped with the card, and yes we were expected to remove the old badges and install the new ones. They came directly from IBM and had a 1 year warranty as I recall.
Thanks for adding this comment - It is great to hear from someone in the computer production area, even if it wasn't directly for IBM. I believe the FRU P/N for this CPU upgrade is listed on the 50/50Z page of the "IBM PC and PS/2 Pocket Reference", and was aware of the included badge with the like-minded "System Board Upgrade" (a rebranded Reply planar) for the Model 70.
Did you ever have the models with the internal slots on a riser card (Model 55 SX)? Had fun with those as if you had a heavy monitor on top of the case, it could bow and wobble the riser card with any small vibration (like somebody closing an officer door) and cause it to crash. What fun root causing that issue was. Solution - stop using the case as a monitor stand.
I worked in computer retail late 80s thru early 90s. Our store was heavily into selling IBM's to banks and businesses. Besides field technician and programmer, I was database and inventory manager. We had thick catalogs of part numbers that would contain those FRU numbers. Sadly I don't have them anymore, but we definitely sold upgrades like that.
I have the identical CPU upgrade (and FPU assembly) in a 7541/7542 "Industrial" system that was also based on the 50Z planar - We have it documented at the 'Ardent-Tool', of course.
I absolutely adore the madness behind this PC. Someone in IBM must have said: - we must upgrade our 286 model 50 system to 486! - but boss, it is completely different architecture .. - GET IT DONE - okaaaaay
@@Epictronics1 Well, there are evidences that it was past prototype, like CPU board had its FRU number, case was made up to production standard, a 'model 50 486-50' badge that was obviously made using its own mold and is of good quality. Maybe it was sold on limited number of markets, like Asia only. The Internet seems to acknowledge this as 286 at 10 MHz as base model and 486 SLC2 as factory upgrade. It only had 1M-2M RAM options, enything more was only available through MCA memory expansions. It was also released as two floppy drive system with no HDD. Much respect foir IBM engineers for fitting 486 into 286 board.
@@86smoke It has an international PSU marked "EN" (none of my other 50Zs are marked "EN"), so it's hard to tell what market it was intended for. I agree, amazing engineering to make a 486 work on a 286 board!
@@Epictronics1 It is not that hard but its a bad idea. The point is 286 uses 16-bit bus, so, by throwing 486 at it, your FSB/RAM bandwidth is cut by half, and SLC models are also not really full fat 486 they have very small L1 cache. Sure this will still beat any 286 or 386 but the actual performance compared to any normal 486 machine will be pretty bad.
Nice machine. I repair and configured this systems back in the day. I love to see you work on IBMs. Greetings from Steven from the Netherlands and i see you next week
First call on one of these was to follow an engineer who had taken every board out the Micro Channel bus. Normally you would reinstall the cards and ask the user for their back up with the driver files as the system would not run if the driver file was not re-installed. The customer did not have one - but luckily on the last day of training an IBMer had given everyone a master disk with all the adf files for every possible configuration. Took 15 minutes to load but it fixed it !
And now *every* ADF (in some cases, multiple versions of the same POS ID) is available at the 'Ardent-Tool'! - The problem now is that the diskette drives don't often work.
IBM included stickers with the upgrade parts - even for modifying the submodel number to the correct CPU encoding. This wasn't a factory release, but was modified later - likely at a hefty price. There's supposed to be a (delicate) PCB with PALs/GALs in the 287 FPU socket. It does bear the question of why do the upgrade rather than get the 386 or 486 level system.
@@Epictronics1: Another limiting factor was that the IBM 386SLC, 486SLC2/486SLC3, and 486DLC2/486BL CPUs could only be used in IBM systems since that was the licensing from Intel for using the 386SX codemask to derive better performance - Hence the Intel copyright on the chip as well. IBM also had produced Intel 386DX CPUs for the Model 70 and 80 that were in the 'silver-cap' packaging during the same era. Of course that preceded later CPU battles that Intel had with competitors.
Okay, you have me hooked. Liked and subscribed! I used the Model 50 in university for machine code programming. I’m pretty sure they were 286s. Nice to see you work on this and I’m keen to see more and the upgrades. Thank you!
The internet also doesn't think the Thinkpad 385CD exists sometimes, turns out it was just so obsolete by the time it came out that even IBM didn't want to acknowledge it. haha
I would love to see you install AIX and OS/2 on some of these IBM computers. I know the PS/2 line had support for both AIX and OS/2 for example. I really want to see “AIXwindows Desktop” running!
@@IBM_Museum so if it was never published means if it was an IBM prototype it never got to the publishing stage simple and was forgotten about otherwise it was simply upgraded later on in it's life
@@raven4k998: It's not a prototype - I have this CPU upgrade board on a 7541/7542 system myself. IBM had "System Board Upgrade" planars that the marketing and CE personnel were aware of when the customer was hooked into having IBM computers and needed better performance.
1:30 in and talk about a possible diamond in the rough here! I'm sure there were a handful out there, but by the time the 486 was out, well.. there were MUCH cheaper alternatives to anything other than the largest companies. Maybe I'm wrong but you may well have a quite rare machine here!! Nice find!
Yes, I think we have a pretty rare machine here. The video has been up for a few days now. A few comments about people remembering these machines from back in the day but no comments so far from owners
At least some of the Hypertec upgrades sold under the "Options by IBM" branding included replacement badges so you could proudly show off your "Official" upgrade. This may have been purchased as a 50Z and upgraded later with the "official" IBM upgrade. Interestingly, they don't appear to have blacked out the Hypertec chips on this upgrade, as opposed to the 13h6698 upgrade for the model 70/80. At least that is the case on my example...
Roman's 50Z system is missing the PCB assembly (there's a picture of it linked from the 'Ardent-Tool' page he referenced - it appears to be *extremely* delicate, and I didn't want to remove it from the 50Z planar of my 7541/7542) that would have gone in the FPU socket; That may be an issue if he tries to use a 387SX/387SL on the CPU upgrade board. The Hypertec CPU upgrade for the 70/80 also had a PAL/GAL PCB that would be installed in the 387DX socket.
I've been kicking myself the last few months. In the very early 2000s, I also had one of these oddballs, though it was labeled as a 50Z 486 (yes, with a factory-looking label as well). The floppy drive died. And then, I (possibly) inadvertently removed the battery. No more booting from the hard drive without booting from the reference disk. Repair for the drive was out of my wheelhouse, and sourcing a replacement drive was impossible at that time. I had many 486 machines at that time, so off to junk it went. Recently, I had been thinking about all the machines I've had in the past, and remembered that one. With more knowledge of IBM PS/2 systems, I started to second-guess myself. 50 and 50Zs are 286 machines. Am I misremembering? I found a photo of the computer, and though the label is blurry, I can still make out that it does have "PS/2 Model 50Z 486" on it. Searched the Internet for any information about this guy, and just like you, came up with absolutely nothing. I would love to know the history behind this computer. Having extra stock of Model 50 parts lying around makes sense. Date codes on the upgrade CPU card are from 93. 1993 is pretty late to still be pushing a 286. But then the bigger question is... why would yours just have a "PS/2 Model 50 486" badge and mine would have a "PS/2 Model 50Z 486" badge, especially since your planar is from a 50Z. We may never have an answer.
Every time I upload a video about an oddball like this, I hope one of the engineers who designed it will see it and comment :) So far, my best guess is that they cleared out the stock of 50Z boards with this crazy upgrade
Yes, the Model 50 and 50Z (as well as the tower Model 60) were based on the 286 CPU; With the Model 50 and 60, it was in PGA (Pin-Grid Array) packaging, and the 50Z had a PLCC (Plastic-Leaded Chip Carrier) 286. The 50Z (aka "Model 50 Type 2") also had a single 72-pin SIMM (instead of two 30-pin), the DBA-ESDI 30Mb or 60Mb HDD (compared to the MFM 20Mb of the Model 50), and "zero wait-states" that gave it the model designation. Another IBM system that had the 50Z planar is the 7541/7541 (whether it was a 'desktop' system with rubber feet, or rack-mount) "Industrial" model - and mine has the same CPU upgrade as shown here.
You should add flux to the component you're removing before you use hot air. Makes removal much faster and it minimizes hot spots that could damage the board.
Wow! I've got a 386 upgrade in one of my model 50s, but I've never seen a 486 upgrade! I imagine it would be a little limited with a 16-bit bus at 24-bit address space, although I'm sure it would still see some big performance improvements for software that ran marginally on a 286. Glad to see the hard drive was still running and no issues with sticky heads. Anyway, looks like this was a relatively easy restoration, but it's always good to see another one back up and running.
@@Epictronics1 That always depends on how much of the benchmark fits into the caches. The RAM speed on that machine is obviously brutally slow for a 486 system, but looking at the cachechk output at @24:10, the L2 cache (which does not even get recognized by cachechk) is only marginally faster. There were 4 of the 256kBit cache chips (and a tag ram chip) on the upgrade PCB, and indeed, you will find the time for 32, 64 and 128K to be around 220ns/byte, whereas bigger blocks are 245ns/byte. As long as the code and data of the benchmark (mostly) fits into the 16K L1 cache on that "super little chip", you will get 486-like performance, and even the clock doubling will work out perfectly. But as soon as your working set exceeds 16K, this machine starts to be mostly waiting for RAM, and the SLC2-50 will just wait twice as many internal cycles than SLC-25 would have waited. Great props to IBM for shipping their 486SLC with a decent amount of L1 cache. The L1 cache of the early Cyrix 486SLC chips is just 1K, and it mostly helps benchmarks, while all real-world software is starved on FSB performance. It always felt completely silly to me that you combine a 486 core with a heavily undersized bus interface (the 386SX interface), then add clock doubling to the core that is already bus starved, and at the same time only provide an eigth of the cache size of a proper Intel 486 processor. IBM did exactly the correct thing by increasing cache size to compensate for the slow bus interface.
The IBM 486SLC2-50 CPU is derived from the Intel 386SX codemask, and is still a 24-bit address/16-bit data bus design, with the same (286/386SX, 16Mb of RAM maximum) limitations. The IBM 386SLC has 8Kb of on-die L1 cache (like an Intel 486-class CPU), and the 486SLC/486DLC versions have 16Kb cache (only done by Intel with late-model 486DX4 CPUs). All of the IBM SLC/DLC CPUs (even the 386SLC) support the Intel 486SX (no FPU) instruction set.
man. I really need to finish the restoration and repair of my Model 50. The owner, a neophyte, when he was going to throw it away (and I rescued it) took it apart and with a couple of slips of the screwdriver he made some scratches that destroyed several lines and some resistors. But I already fixed everything. Now I'm about to start with the power supply. But I got distracted with a 386 motherboard that was badly damaged by the battery, with which I'm close to finishing its restoration. But the thing is that I have a lot of things to do and try, and I do a little of each, but I don't complete any of them, hahaha
@@Epictronics1 It weirded me out when you pushed it down and it turned on. I was going to comment that I'd never seen an IBM power switch where down was on, but I assumed that that's how this one was supposed to be.
Very interesting to see. The first computer I built was an SLC2-50 machine. It was a soldered on CPU and obviously more like a 386 board, but it was very cheap in mid 1993.
A few days ago, a blue no-name branded film capacitor blew up in my ATX power supply which was a part of snubber circuit. I think RIFAs are not alone in that league.
Interesting find! I had a Model 50Z as first machine, too - albeit upgrading from an Atari XE ;). Mine also had a white switch - and it was off a batch of which a lot of the machines went to my school - all of them with white switches. So that was standard at some point. I personally never liked it because it was a 286 (all the cool stuff needed a 386), no standard upgrades worked (so no Soundblaster off the shelf), and only standard VGA, so no 256 colors at 640x480, which was the cool stuff at the time. A 486 SLC might have changed my opinion... Then went onto a standard Pentium based machine, and never looked back. Imagine going suddenly more than 100 times faster... (0.9 Mips on 286-10 vs. 126 on P75)
I made a fortune in overtime back in the '90s replacing endless delay lines on the Model 50Z. £100 a time for the company, I got 20%. I used to do about 20 boards over a weekend. Did it for months. Unfortunately I was young and dumb and spent it most of it on beer and night clubs. Often doing overtime with a stinking hang-over - great times.
The device in the middle of the board labelled PE-27081 is a 50nS delay line used to correct the time difference on memory address caused by the board track length. These often failed causing the board not to POST.
I fried my Cyrix "Make-it 486" CPU upgrade years ago by installing it into a 387 MCP socket. Haven't found a replacement since... although what I had wasn't really a 486 either. To my understanding, it was a Cyrix 386 soldered to a PCP which also contained a 1 KB cache chip. I'm pretty sure the cache was a separate chip on the PCB but don't quote me on that. I can attest that the machine booted with the CPU, I used it on a PS/2 and I may have used it on a PC/AT (my PC/AT has a upgraded modular BIOS).
I remember setting these up for a college back in the day. One user used hers as a footrest, she took her shoes off and rubbed her feet on it all day until dead skin got caked on. It was not fun to work on that one..
I have a 286 based PC9801 that has a 486 upgrade very similar to that and there are plenty of parts online. So it seems this was a very common upgrade over seas.
Now that is a very interesting thought. That's exactly what we did in the IBM PS/1 486SX video. I disabled the onboard 486SX with a bodge wire and installed a 5x86 in the 487 socket. The only problem is that I don't think there is a 487 in this form factor.
@@Epictronics1well that IBM/Hypertech(?) accelerator has an FPU socket, right? It also comes with a 486/SX soldered processor… so some 487 FPU has to fit it. If it has an FPU socket some FPU should fit in is my logic
486 SLCs, from what I see online, are not actually i486s. There is a Cyrix design, and a different one that IBM made based on the i386, and in any case they have a 386 electrical interface and would interact with a 387 coprocessor in the normal way.
Found this quite from a 2017 forum post: There are other, far more substantial upgrades and peripherals I’d like to add to it, such as the IBM 486SLC2-50/25 processor upgrade kit (incredibly rare and prohibitively expensive if you do find one) or a math co-processor (haven’t been able to find one).
What is the model-submodel encoding? The 50Z came with a 30Mb (8550-031) or 60Mb (8550-061) as shown. The Model 50 came with the blue eject 'big-button' drives (and the red power switch as you like), the 50Z and Model 70 came with 'small-button', having an additional PCB to use the later pin-connect drives. BTW, the Model 70 did have two 486 versions, the 486DX-25 by having the CPU and BIOS update, and also a "System Board Upgrade" that was rebadged from Reply, with a 33MHz base clock (the DX2-33 and even AMD 5x86-133 upgrades could work on it).
I have always found ChipQuik to be far more trouble than it's worth. It's incredibly messy and has a chance to contaminate the solder of nearby components. What you really need is a set of tweezer tips for your iron. Makes removing those SMD electrolytics a piece of cake.
What a fascinating system. Since IBM sold so many of the Model 50, it makes sense to me that they commissioned an upgrade path. Replacing the planar with a Model 70 could have been an option, but would also require the addition of a hard drive controller and new hard drive at a minimum. This "plug in" upgrade retains more of the original components and seems like it requires minimal labour to install. The 128KB of cache SRAM on the upgrade board would be crucial for performance since the RAM on the planar is limited to 10MHz on a 16-bit bus. My guess is that this would be a dealer or field technician installed upgrade, and the kit included the CPU upgrade board and the new top case with side vents and 486 badge.
Would not surprise me if the side vents were also dealer/field installed (or at least a one-in-one-out swap scheme) as punching a few extra cooling holes in the case sides is going to be a lot cheaper than replacing the hole case top.
If I may add to your explanation as to to how the Chip Quick works, it stays molten for longer, because the melting point is so low (hence it needs a lot more time to re-harden).
The reason the Panasonic batteries rarely leak is because they're lithium. Pretty much all lithium chemistries have similar failure modes, none of which involves a strong base or acid fuming out. It's still technically possible for a lithium battery to leak, but it's rare and nowhere near as corrosive as Ni-Cad or alkaline batteries. Still can ruin electronics regardless.
That was some really good engineering, if they got 286 motherboard upgraded to a clock-doubled 486/50 to out-perform a 386DX-40. I remember those kinds of upgrades existing and they rarely offered good performance, because they were hobbled by the limitations of the 286 board. Usually, you could hack a 486 onto a 386 design and it would work well enough, but the 286 was a bridge too far.
I have seen that cpu upgrade board in some youtube video, but can not find it now. If you are very curious, it would be worth to image the full hard drive and try data recovery/reconstruction :) a clean install would overwrite just some parts of it. So .. shall we dig deeper?
I have one for a a PS/2 Model 60, 50, and 50Z... It's a 50mhz 486 SLC2. IBM had them made and they came with upgrade badges. I have an imgur link of the package contents and another showing benchmarks if you want it.
Thanks. Yes, that would be very interesting to see. I think YT automatically removes comments with links. Please send the link to epictronicsyt@gmail.com
I know back in the day there were 486DX-50's, as in not-DX/2's. The DX/2's got higher clockspeeds by doubling the bus clock. But the far faster bus on the DX-50 helped a great deal. I thought the DX-50 came quite close to the DX/2-66 at times.
I do think I've seen a similar "model 40 486" or similar many years ago. The converter CPU boards meant that you could indeed put a different CPU in and I think they where supposed to be cheaper than a proper 486 etc. The main issue was the bus width and I think clock speeds? If you had the cash you were better off getting a proper 486. Mind you the PS/2 machines were renowned for having custom bios stuff/hardware that broke the usual "standards" of the time. Same with compaq and I think HP. You could get many clone PCs that were running AMI or Phoenix bioses and they ran all the games and other software fine. My recollection for the incompatibility were things like GFX(Their implementation of MDA/MCGA etc I think was a bit different),fonts and I think some internal DOS/BIOS/interrupt tables were different than the standard.
"Their implementation of MDA/MCGA etc I think was a bit different),fonts and I think some internal DOS/BIOS/interrupt tables were different than the standard." Only IBM (on the 8086-based Model 25 and Model 30, and a couple derivative systems based on their planars) and the Epson Equity 1e used MCGA - and MCGA was never on a separate adapter. There are a couple fonts that changed with MCGA, and different versions of the IBM CGA adapter. And the IBM BIOS versions add more BIOS calls (like INT 15h, Function C9h for CPU information) than the clone manufacturers had in the CBIOS, and had the IBM-specific ABIOS section.
@IBM_Museum yeah my memory is vague with the differences but there were definately some incompatabilities and i know some of them were things like how the memory was layed out etc. I had a model 30 xt version at one point and a couple of others later.
@@skilletpan5674: The 486SLC2 and 486SLC3 are clock doubled and tripled respectively, but are 16-bit external data bus and 24-bit address bus (meaning 16Mb of RAM maximum). The 486DLC2/486BL2 are 32-bit CPUs that are clock-doubled. Very different limitations.
19:40 Be EXTREMELY careful with that PLCC68 male socket, they are unobtanium now. The 486SLC is really just a 386sx with 16kB L1 cache and 486 instruction set but only has a 16-bit data bus so it's not a true 486. Performance will be somewhere between 386 and 486.
What would make me suspicious (about it being a factory 486), is the absence of a CD-Rom drive. And I guess, the badges would have been shipped with the upgrade kit.
I have finally managed to find one of the silly-rare external PS/2 drives for these machines :) It's in a pretty bad condition though so, we'll have to restore it in a video
Oh, I finally broke down and purchased a 3d printer. I found the Creality Ender 3 S1 Pro (the one to get if you're going 'cheap'. It was $187 BRAND NEW on eBay direct from Creality America.. As far as I'm concerned I STOLE this thing.. it has basically PAID for itself already, I have printed 2 clips to fix the handle on my refrigerator, a few other little things as well, but.. even with some accessories like a filament dryer, 6 kilos of filament (assorted flavors and colors) the enclosure (for temp and humidify control) a vacuum bag machine and bags.. you know, have to have all the goodies to go along with it, but I think I'm in under $400 with enough filament to last probably 6 months of printing. I am SO excited.. I can replace ALL the broken plastics from all my old machines now and do them correct, MYSELF. I am SO excited!!
@AnthonyRBlacker - congratulations on your purchase. I hope your supplies last six months. Seriously. Once you start printing, and designing and printing… consumables are consumed. They are addictive because unlike most modern electronics, 3D printing involves a tinker element. You find you cannot leave them alone. Good luck! It’s rewarding when you design something for work or home that has never existed before. When someone sees a print in action as a functional tool and ask,”Where did you get this?” and you tell them that you printed it… people look at you differently. It’s still a realm where some folks consider 3D printers to be a form of ‘witchcraft’ and a designer/maker to have supernatural skills. I have two filament and two resin printers. My friend has four printers. She cannot stop printing new stuff. Good luck!
The only reason this works is because the 386SX was a drop-in for 286 chipset boards. and then tyhe 486SLC was a drop-in for that, all in the name of cost cutting. and in IBM's case, not so much.
I had a ALR Powerflex way back when. It was designed as a 286 that had a 386 or 486 daughter board that could be installed. When installed it disabled the onboard 286. I imagine that IBM utilized a similar concept here. As I remember though the performance was pretty limited compared to proper motherboard as there was a significant bottleneck to the memory.
Wow, this is gorgeous! I’m almost done with restoring a 50Z (also my first x86 PC) - I’m just really struggling finding a working 1.44MB floppy. Any chance you know someone who repairs them (I have several dead ones) or has spare working drives?
Now that I’ve finished watching the video, I see you did the floppy repair yourself. I’d be happy to hire your services to fix the drives I have if you’re interested. Long story short, my project involves both a 50Z and a Model 70. I’ve done a bunch of work to virtualize a Banyan VINES server and plan to use the 50Z and 70 as VINES clients. Everything works except the floppy drive. I’ve got an emulator in place that let me install what I need to (including the Ethernet drivers) - but want to get a real floppy drive in place to make it 100% authentic. Amazing machines that deserve restoration and preservation!
@@dmurphynj Sorry, I'm already working two full-time jobs so no chance to take on any repairs. You could check with your local vintage computer club. Hopefully, someone there could help you. Good luck with the project!
The lack of documentation on this "model" makes me think this must have been a localized upgrade offered by IBM only in specific international markets. The badge does indicate to me this was an IBM-installed upgrade. I'm easily imagining some ads in local newspapers and magazines, and you had to bring in your machine to an authorized center for service, where the upgrade would be performed. As part of the upgrade, the badge on your case would be changed as well. I'm guessing the upgrade would have been pretty expensive, and very few people did it, preferring to change their computer entirely instead. Obviously this is all pure speculation, but this is the story/scenario that makes the most sense in my head.
IBM was licensed to use the 386SX codemask from Intel (hence the Intel copyright on the chip) with the limitation that the derived CPUs (386SLC, 496SLC2/486SLC3, and 486DLC2/486BL) only be used on IBM systems. I'm sure IBM charged a premium for installing this upgrade, although the IBM CE would come out to the customer premises as well for a business. Years ago, I was contacted by a (U.S.) power company that wanted to replace a failed diskette drive for a Model 50Z, and declined my offers to replace the entire system with something newer (it probably had an industrial microchannel adapter for monitoring, but I offered a PS/2 Model 77 as a substitute).
It could be a special bid unit that Ibm made for a company or organization. If you provide the numeric model number from the rear, might be able to find some information on it.
i will say to this, my 286 back in the day, when i was kid, looked this, with holes on the side, the difference is on the front, where the floppy disk was, instead of the big hole you have for the botton, it had a small hole instead, so the floppy drive you had inside, looked original. i will say the 286 came from my moms work and got it in 94, idk if has something to do with design of the case.
@@Epictronics1: And systems that are stored away are more likely to develop the "whiskers" and have ambient humidity saturate the tantalums than electronics that are used...
Have a PS/2-30 286 ( from ~1988 ) which were upgraded with a similar Kingston 386SLC + ITT 387SX 25MHz daughter-board. The PC was used to run Berkeley Spice. The price/performance of CPU's dropped aggressively at the same time, so the upgrade was probably not worth it. 🙄
Our family had one of these back in the day (my Dad worked at IBM at the time). It always seemed a bit of an odd upgrade option even back in the day. Fortunately working at IBM at the time, I think he got a very good deal on the upgrade board and yes we had the 50z case at the time. Ours started off as a standard 286, then got a 386 upgrade (was a riser board which plugged into the 286 socket), then we upgraded to this board. While it was a "decent" upgrade at the time, certainly by the time we got ours, it was already nowhere near what was out there in the market. The 486SLC2/50 processor really wasn't that fast. The microchannel bus also continued to make the machine rather limiting at the time. The reality is we upgraded to a better machine quite quickly after that to get multimedia capability. An IBM PS/ValuePoint 486DX2/66, with sound card and CD-Rom, which itself was later upgraded with an Intel Pentium Overdrive 83Mhz chip.
IBM had to change the power switch from red to white because of a government regulation that red buttons and switches could only be used for an emergency stop/shutoff function. That's also why the red reset button on Tandy computers changed from red to white around the same time (circa 1990).
That's a bummer. I really liked the red switches :)
Government ruins everything
And what would a hard-power cut off switch be, but an emergency stop switch?
The reason computers had a bland era was because German regulations saying computers should blend in and be "unoffensive" to the office space.
Likely not 100% accurate and kind on BS side. Power strip have red buttons, plenty other appliances on/off switch was, are and will be red, record buttons are red. Someone took few line from multi-tome/page regulation and twisted interesting ways for some purpose and/or just was incompetent.
Bright Red and Green usage are regulated on railways (direct sight of locomotive operator and stuff), red brick house and green pain not banded and plentiful around railways.
Well that was a trip down memory lane LOL.
I remember these; I worked for a company in London around 1993 that had a ton of Model 50's that they wanted upgraded to be capable of running Windows 3.1. The 286 wasn't going to cut it and they didn't want to splash out the budget for new 386 or 486 PC's... so I and my team were tasked with installing these exact CPU upgrades into their Model 50's... I personally must've installed 15-20 of them. They worked... they definitely weren't as fast as a true 486 mostly because the RAM was still running at 286 speeds, but they provided a relatively cost effective way of extending the lifespan of these Model 50's they had already and performed on par or slightly better than my PC which was a newer 55 Model 386.
The badge was shipped with the card, and yes we were expected to remove the old badges and install the new ones. They came directly from IBM and had a 1 year warranty as I recall.
Thanks for adding this comment - It is great to hear from someone in the computer production area, even if it wasn't directly for IBM. I believe the FRU P/N for this CPU upgrade is listed on the 50/50Z page of the "IBM PC and PS/2 Pocket Reference", and was aware of the included badge with the like-minded "System Board Upgrade" (a rebranded Reply planar) for the Model 70.
Poor me had to cope with the original 10MHz 286 on my Model 50 running Win3.1 back in the day :D
Amazing insight!
Did you ever have the models with the internal slots on a riser card (Model 55 SX)? Had fun with those as if you had a heavy monitor on top of the case, it could bow and wobble the riser card with any small vibration (like somebody closing an officer door) and cause it to crash. What fun root causing that issue was. Solution - stop using the case as a monitor stand.
I worked in computer retail late 80s thru early 90s. Our store was heavily into selling IBM's to banks and businesses. Besides field technician and programmer, I was database and inventory manager. We had thick catalogs of part numbers that would contain those FRU numbers. Sadly I don't have them anymore, but we definitely sold upgrades like that.
That machine is build like a tank.
Also looks really good with all those pcb connectors instead of wires.
Really a product of quality.
I have the identical CPU upgrade (and FPU assembly) in a 7541/7542 "Industrial" system that was also based on the 50Z planar - We have it documented at the 'Ardent-Tool', of course.
Interesting. Is there more documentation about this besides the info on Ardent?
I absolutely adore the madness behind this PC. Someone in IBM must have said:
- we must upgrade our 286 model 50 system to 486!
- but boss, it is completely different architecture ..
- GET IT DONE
- okaaaaay
lol. This IBM doesn't make any sense! I'm starting to think it's a prototype that wasn't intended to go into production
@@Epictronics1 Well, there are evidences that it was past prototype, like CPU board had its FRU number, case was made up to production standard, a 'model 50 486-50' badge that was obviously made using its own mold and is of good quality. Maybe it was sold on limited number of markets, like Asia only.
The Internet seems to acknowledge this as 286 at 10 MHz as base model and 486 SLC2 as factory upgrade. It only had 1M-2M RAM options, enything more was only available through MCA memory expansions. It was also released as two floppy drive system with no HDD.
Much respect foir IBM engineers for fitting 486 into 286 board.
@@86smoke It has an international PSU marked "EN" (none of my other 50Zs are marked "EN"), so it's hard to tell what market it was intended for. I agree, amazing engineering to make a 486 work on a 286 board!
It's not a real 486, but a 486slc weirdo.
@@Epictronics1 It is not that hard but its a bad idea. The point is 286 uses 16-bit bus, so, by throwing 486 at it, your FSB/RAM bandwidth is cut by half, and SLC models are also not really full fat 486 they have very small L1 cache. Sure this will still beat any 286 or 386 but the actual performance compared to any normal 486 machine will be pretty bad.
Nice machine. I repair and configured this systems back in the day. I love to see you work on IBMs. Greetings from Steven from the Netherlands and i see you next week
Thanks :)
First call on one of these was to follow an engineer who had taken every board out the Micro Channel bus. Normally you would reinstall the cards and ask the user for their back up with the driver files as the system would not run if the driver file was not re-installed. The customer did not have one - but luckily on the last day of training an IBMer had given everyone a master disk with all the adf files for every possible configuration.
Took 15 minutes to load but it fixed it !
And now *every* ADF (in some cases, multiple versions of the same POS ID) is available at the 'Ardent-Tool'! - The problem now is that the diskette drives don't often work.
I love you professor tapping everything with the stick
IBM included stickers with the upgrade parts - even for modifying the submodel number to the correct CPU encoding. This wasn't a factory release, but was modified later - likely at a hefty price. There's supposed to be a (delicate) PCB with PALs/GALs in the 287 FPU socket. It does bear the question of why do the upgrade rather than get the 386 or 486 level system.
Cool, do you have any documentation about this?
not every customer had the funds to replace tech, upgrades ran through different channels, made perfect sense in its day
@@Epictronics1: Another limiting factor was that the IBM 386SLC, 486SLC2/486SLC3, and 486DLC2/486BL CPUs could only be used in IBM systems since that was the licensing from Intel for using the 386SX codemask to derive better performance - Hence the Intel copyright on the chip as well. IBM also had produced Intel 386DX CPUs for the Model 70 and 80 that were in the 'silver-cap' packaging during the same era. Of course that preceded later CPU battles that Intel had with competitors.
Many years ago I had a model 50 386 i got in a scrap pickup. It looked like a genuine thing.
Okay, you have me hooked. Liked and subscribed!
I used the Model 50 in university for machine code programming. I’m pretty sure they were 286s.
Nice to see you work on this and I’m keen to see more and the upgrades.
Thank you!
Thanks!
Very interesting machine 😊
Amazing IBM!
I love the modules for this machine, very well thought out.
Nice video, very calming and informative...
Thanks :)
The internet also doesn't think the Thinkpad 385CD exists sometimes, turns out it was just so obsolete by the time it came out that even IBM didn't want to acknowledge it. haha
Top notch video, as usual here! Great time watching these production of yours. Cheers
Thanks!
I would love to see you install AIX and OS/2 on some of these IBM computers. I know the PS/2 line had support for both AIX and OS/2 for example. I really want to see “AIXwindows Desktop” running!
I'm definitely considering it!
Was a special model 80 that could run AIX
Congrats on the awesome find; and it indeed looks really cool too with the blue and red. Can't wait for next weeks' video about it !!!
Thanks! It's going to take a few weeks to find all the parts I need for the upgrade
Wow this brings back memories. Thank you!
I clicked this so fast, now to wait 5 more minutes. You got me!
Gets a pretty clean machine. Cleans it even more. Boots! Great video.
according the the innerweb's this computer does not exist
@@raven4k998: But the processor upgrade FRU P/N does exist in IBM documentation, like the "IBM PC and PS/2 Pocket Reference"...
@@IBM_Museum so if it was never published means if it was an IBM prototype it never got to the publishing stage simple and was forgotten about otherwise it was simply upgraded later on in it's life
@@raven4k998: It's not a prototype - I have this CPU upgrade board on a 7541/7542 system myself. IBM had "System Board Upgrade" planars that the marketing and CE personnel were aware of when the customer was hooked into having IBM computers and needed better performance.
1:30 in and talk about a possible diamond in the rough here! I'm sure there were a handful out there, but by the time the 486 was out, well.. there were MUCH cheaper alternatives to anything other than the largest companies. Maybe I'm wrong but you may well have a quite rare machine here!! Nice find!
Yes, I think we have a pretty rare machine here. The video has been up for a few days now. A few comments about people remembering these machines from back in the day but no comments so far from owners
Noctua fan and MORE goodies?! Yes!!!
Worked as a tech on all of the ps/2 models. Extremely easy to take apart and reassemble. Weighed a ton though :-)
This one is a keeper.... create the perfect picture you always wanted to
I know little about fixing computers.
But I still find your videos interesting and I am a subscriber.
Just sayin'.
☮
Thank you :)
This was the PC we used to run our restaurant POS system back when I started working there in 1999. Just without the upgrade.
I ran a 386-DX40, that’s a HELL of an upgrade
Dude what the heck?! This is an insanely rare find!
an old IBM upgraded system so cool very rare find
Very nice. What a fancy upgrade!!
Thanks. Yeah, this upgrade is unreal!
Toujours un plaisir de visionner vos vidéos 🤗🖥️🩺
Merci. J'ai vécu en France de 1982 à 1983 :)
No fun in Germany only Wörk, so no Games! Nice Vid, Greetings from Germany 😅
haha, thanks. I prefer games to wörk any day lol
At least some of the Hypertec upgrades sold under the "Options by IBM" branding included replacement badges so you could proudly show off your "Official" upgrade. This may have been purchased as a 50Z and upgraded later with the "official" IBM upgrade. Interestingly, they don't appear to have blacked out the Hypertec chips on this upgrade, as opposed to the 13h6698 upgrade for the model 70/80. At least that is the case on my example...
Roman's 50Z system is missing the PCB assembly (there's a picture of it linked from the 'Ardent-Tool' page he referenced - it appears to be *extremely* delicate, and I didn't want to remove it from the 50Z planar of my 7541/7542) that would have gone in the FPU socket; That may be an issue if he tries to use a 387SX/387SL on the CPU upgrade board. The Hypertec CPU upgrade for the 70/80 also had a PAL/GAL PCB that would be installed in the 387DX socket.
I've been kicking myself the last few months. In the very early 2000s, I also had one of these oddballs, though it was labeled as a 50Z 486 (yes, with a factory-looking label as well). The floppy drive died. And then, I (possibly) inadvertently removed the battery. No more booting from the hard drive without booting from the reference disk. Repair for the drive was out of my wheelhouse, and sourcing a replacement drive was impossible at that time. I had many 486 machines at that time, so off to junk it went.
Recently, I had been thinking about all the machines I've had in the past, and remembered that one. With more knowledge of IBM PS/2 systems, I started to second-guess myself. 50 and 50Zs are 286 machines. Am I misremembering? I found a photo of the computer, and though the label is blurry, I can still make out that it does have "PS/2 Model 50Z 486" on it. Searched the Internet for any information about this guy, and just like you, came up with absolutely nothing.
I would love to know the history behind this computer. Having extra stock of Model 50 parts lying around makes sense. Date codes on the upgrade CPU card are from 93. 1993 is pretty late to still be pushing a 286. But then the bigger question is... why would yours just have a "PS/2 Model 50 486" badge and mine would have a "PS/2 Model 50Z 486" badge, especially since your planar is from a 50Z. We may never have an answer.
Every time I upload a video about an oddball like this, I hope one of the engineers who designed it will see it and comment :) So far, my best guess is that they cleared out the stock of 50Z boards with this crazy upgrade
Yes, the Model 50 and 50Z (as well as the tower Model 60) were based on the 286 CPU; With the Model 50 and 60, it was in PGA (Pin-Grid Array) packaging, and the 50Z had a PLCC (Plastic-Leaded Chip Carrier) 286. The 50Z (aka "Model 50 Type 2") also had a single 72-pin SIMM (instead of two 30-pin), the DBA-ESDI 30Mb or 60Mb HDD (compared to the MFM 20Mb of the Model 50), and "zero wait-states" that gave it the model designation. Another IBM system that had the 50Z planar is the 7541/7541 (whether it was a 'desktop' system with rubber feet, or rack-mount) "Industrial" model - and mine has the same CPU upgrade as shown here.
You should add flux to the component you're removing before you use hot air. Makes removal much faster and it minimizes hot spots that could damage the board.
Beautiful modular design.
Neat modularity
Wow! I've got a 386 upgrade in one of my model 50s, but I've never seen a 486 upgrade! I imagine it would be a little limited with a 16-bit bus at 24-bit address space, although I'm sure it would still see some big performance improvements for software that ran marginally on a 286. Glad to see the hard drive was still running and no issues with sticky heads. Anyway, looks like this was a relatively easy restoration, but it's always good to see another one back up and running.
Yes, I don't expect it to be as fast as a "proper" 486DX2-50 but the benchmarks indicated that it's not too far off!
@@Epictronics1 That always depends on how much of the benchmark fits into the caches. The RAM speed on that machine is obviously brutally slow for a 486 system, but looking at the cachechk output at @24:10, the L2 cache (which does not even get recognized by cachechk) is only marginally faster. There were 4 of the 256kBit cache chips (and a tag ram chip) on the upgrade PCB, and indeed, you will find the time for 32, 64 and 128K to be around 220ns/byte, whereas bigger blocks are 245ns/byte.
As long as the code and data of the benchmark (mostly) fits into the 16K L1 cache on that "super little chip", you will get 486-like performance, and even the clock doubling will work out perfectly. But as soon as your working set exceeds 16K, this machine starts to be mostly waiting for RAM, and the SLC2-50 will just wait twice as many internal cycles than SLC-25 would have waited.
Great props to IBM for shipping their 486SLC with a decent amount of L1 cache. The L1 cache of the early Cyrix 486SLC chips is just 1K, and it mostly helps benchmarks, while all real-world software is starved on FSB performance. It always felt completely silly to me that you combine a 486 core with a heavily undersized bus interface (the 386SX interface), then add clock doubling to the core that is already bus starved, and at the same time only provide an eigth of the cache size of a proper Intel 486 processor. IBM did exactly the correct thing by increasing cache size to compensate for the slow bus interface.
The IBM 486SLC2-50 CPU is derived from the Intel 386SX codemask, and is still a 24-bit address/16-bit data bus design, with the same (286/386SX, 16Mb of RAM maximum) limitations. The IBM 386SLC has 8Kb of on-die L1 cache (like an Intel 486-class CPU), and the 486SLC/486DLC versions have 16Kb cache (only done by Intel with late-model 486DX4 CPUs). All of the IBM SLC/DLC CPUs (even the 386SLC) support the Intel 486SX (no FPU) instruction set.
man. I really need to finish the restoration and repair of my Model 50. The owner, a neophyte, when he was going to throw it away (and I rescued it) took it apart and with a couple of slips of the screwdriver he made some scratches that destroyed several lines and some resistors. But I already fixed everything. Now I'm about to start with the power supply. But I got distracted with a 386 motherboard that was badly damaged by the battery, with which I'm close to finishing its restoration. But the thing is that I have a lot of things to do and try, and I do a little of each, but I don't complete any of them, hahaha
19:44 Hypertec was an Australian PC manufacturer back in the days. That may explain the 50hz crystal on the PCB??
Can you fix the orientation of the switch? Up is supposed to be On.
haha, I didn't think anyone would notice 😅 Apparently, this P/N is "upside down" We'll fix it in the follow-up video!
@@Epictronics1 It weirded me out when you pushed it down and it turned on. I was going to comment that I'd never seen an IBM power switch where down was on, but I assumed that that's how this one was supposed to be.
This was the comment i'm searching for ;-)
Check that cache is enabled in BIOS
Very interesting to see. The first computer I built was an SLC2-50 machine. It was a soldered on CPU and obviously more like a 386 board, but it was very cheap in mid 1993.
A few days ago, a blue no-name branded film capacitor blew up in my ATX power supply which was a part of snubber circuit. I think RIFAs are not alone in that league.
If it's blue, it's probably a WIMA. They smell really bad! I have washed my display with a blown WIMA, but it still stinks of burned electronics!
Thats pretty cool.
Got an MCA 386 upgrade card in my model 50, but its no 486!
Nice find there. Please make sure to document it :)
Holy crap I had it as a kid and I used to learn turbo pascal and basic on it
Interesting find! I had a Model 50Z as first machine, too - albeit upgrading from an Atari XE ;). Mine also had a white switch - and it was off a batch of which a lot of the machines went to my school - all of them with white switches. So that was standard at some point.
I personally never liked it because it was a 286 (all the cool stuff needed a 386), no standard upgrades worked (so no Soundblaster off the shelf), and only standard VGA, so no 256 colors at 640x480, which was the cool stuff at the time. A 486 SLC might have changed my opinion...
Then went onto a standard Pentium based machine, and never looked back. Imagine going suddenly more than 100 times faster... (0.9 Mips on 286-10 vs. 126 on P75)
Same thing here. I upgraded from a C64 to the Model 50 and then later to a Pentium. Things changed rapidly back then!
I made a fortune in overtime back in the '90s replacing endless delay lines on the Model 50Z. £100 a time for the company, I got 20%. I used to do about 20 boards over a weekend. Did it for months. Unfortunately I was young and dumb and spent it most of it on beer and night clubs. Often doing overtime with a stinking hang-over - great times.
Sounds like fun! What do you mean by replacing delay lines?
The device in the middle of the board labelled PE-27081 is a 50nS delay line used to correct the time difference on memory address caused by the board track length. These often failed causing the board not to POST.
@@radio-ged4626 That could be useful to know. Thanks
What an epic find! Amazing!
I've got one of those. Would love to build a stealth system outta it.
The backwards power switch mod is pretty neat too! ;P
Can't wait to see Doom run on this!
I didn't think anyone would notice lol
@@Epictronics1 Hahaha :) I think I totally understand why though! Must be quite the effort to get to that switch once everything's reassembled.
@@jerther_ Apparently this Arrow P/N is "upside down" :) We'll flip it in the follow up vid
Oh the switch itself is made upside down! Interesting! Are you going to mod it? That'd be quite a feat 😁
@@jerther_ I'm gonna try to install it upside down first
I fried my Cyrix "Make-it 486" CPU upgrade years ago by installing it into a 387 MCP socket. Haven't found a replacement since... although what I had wasn't really a 486 either. To my understanding, it was a Cyrix 386 soldered to a PCP which also contained a 1 KB cache chip. I'm pretty sure the cache was a separate chip on the PCB but don't quote me on that. I can attest that the machine booted with the CPU, I used it on a PS/2 and I may have used it on a PC/AT (my PC/AT has a upgraded modular BIOS).
I remember setting these up for a college back in the day. One user used hers as a footrest, she took her shoes off and rubbed her feet on it all day until dead skin got caked on. It was not fun to work on that one..
I have a 286 based PC9801 that has a 486 upgrade very similar to that and there are plenty of parts online. So it seems this was a very common upgrade over seas.
What a beauty....
I agree!
My understanding is if you put in the i487 FPU it’s just a i486DX, it turns off the 486SX processor on board
Now that is a very interesting thought. That's exactly what we did in the IBM PS/1 486SX video. I disabled the onboard 486SX with a bodge wire and installed a 5x86 in the 487 socket. The only problem is that I don't think there is a 487 in this form factor.
@@Epictronics1well that IBM/Hypertech(?) accelerator has an FPU socket, right? It also comes with a 486/SX soldered processor… so some 487 FPU has to fit it. If it has an FPU socket some FPU should fit in is my logic
@@Epictronics1 The SLC is a 386sx replacement, so the FPU would be a 387sx or clone
@@matthewday7565 That kinda sucks a little bit :)
486 SLCs, from what I see online, are not actually i486s. There is a Cyrix design, and a different one that IBM made based on the i386, and in any case they have a 386 electrical interface and would interact with a 387 coprocessor in the normal way.
Found this quite from a 2017 forum post:
There are other, far more substantial upgrades and peripherals I’d like to add to it, such as the IBM 486SLC2-50/25 processor upgrade kit (incredibly rare and prohibitively expensive if you do find one) or a math co-processor (haven’t been able to find one).
This must be an exceptionally lucky find
Can't wait for next episode
What is the model-submodel encoding? The 50Z came with a 30Mb (8550-031) or 60Mb (8550-061) as shown. The Model 50 came with the blue eject 'big-button' drives (and the red power switch as you like), the 50Z and Model 70 came with 'small-button', having an additional PCB to use the later pin-connect drives. BTW, the Model 70 did have two 486 versions, the 486DX-25 by having the CPU and BIOS update, and also a "System Board Upgrade" that was rebadged from Reply, with a 33MHz base clock (the DX2-33 and even AMD 5x86-133 upgrades could work on it).
That's very cool. I need to find one of those boards. I'll check the model number, probably 061
I had a model 50 as a NetWare Lite file server at one point, the 286 of course
I have always found ChipQuik to be far more trouble than it's worth. It's incredibly messy and has a chance to contaminate the solder of nearby components. What you really need is a set of tweezer tips for your iron. Makes removing those SMD electrolytics a piece of cake.
What a fascinating system. Since IBM sold so many of the Model 50, it makes sense to me that they commissioned an upgrade path. Replacing the planar with a Model 70 could have been an option, but would also require the addition of a hard drive controller and new hard drive at a minimum. This "plug in" upgrade retains more of the original components and seems like it requires minimal labour to install. The 128KB of cache SRAM on the upgrade board would be crucial for performance since the RAM on the planar is limited to 10MHz on a 16-bit bus. My guess is that this would be a dealer or field technician installed upgrade, and the kit included the CPU upgrade board and the new top case with side vents and 486 badge.
That makes perfect sense. But why is this the only known IBM to have this upgrade?
Would not surprise me if the side vents were also dealer/field installed (or at least a one-in-one-out swap scheme) as punching a few extra cooling holes in the case sides is going to be a lot cheaper than replacing the hole case top.
If I may add to your explanation as to to how the Chip Quick works, it stays molten for longer, because the melting point is so low (hence it needs a lot more time to re-harden).
Yeah, I realized my mistake while editing :D It's kinda the same thing
The reason the Panasonic batteries rarely leak is because they're lithium. Pretty much all lithium chemistries have similar failure modes, none of which involves a strong base or acid fuming out. It's still technically possible for a lithium battery to leak, but it's rare and nowhere near as corrosive as Ni-Cad or alkaline batteries. Still can ruin electronics regardless.
That was some really good engineering, if they got 286 motherboard upgraded to a clock-doubled 486/50 to out-perform a 386DX-40. I remember those kinds of upgrades existing and they rarely offered good performance, because they were hobbled by the limitations of the 286 board. Usually, you could hack a 486 onto a 386 design and it would work well enough, but the 286 was a bridge too far.
I wasn't expecting much either, but this thing actually performs
I have seen that cpu upgrade board in some youtube video, but can not find it now. If you are very curious, it would be worth to image the full hard drive and try data recovery/reconstruction :) a clean install would overwrite just some parts of it. So .. shall we dig deeper?
I have one for a a PS/2 Model 60, 50, and 50Z... It's a 50mhz 486 SLC2. IBM had them made and they came with upgrade badges. I have an imgur link of the package contents and another showing benchmarks if you want it.
Thanks. Yes, that would be very interesting to see. I think YT automatically removes comments with links. Please send the link to epictronicsyt@gmail.com
neozeed just found something like this, built by third party, for his ps/2 model 60. it's fun to see something similar is done by IBM.
Will you be trying for the additional FPU??
I'm pretty sure I have one, but I don't think I know of a game that would make any use of it
Nice PC!
I know back in the day there were 486DX-50's, as in not-DX/2's. The DX/2's got higher clockspeeds by doubling the bus clock. But the far faster bus on the DX-50 helped a great deal. I thought the DX-50 came quite close to the DX/2-66 at times.
Yes, I've got a DX50. It's great, but picky with VLB cards!
Clean, joyless hard drive with nothing fun on it. Hard to believe it came from Germany.
Crazy upgrade. Can you compare the fastest 286 supported by this board and this 486 upgrade ?
Yes, I plan to do some comparisons in a follow up video
I do think I've seen a similar "model 40 486" or similar many years ago. The converter CPU boards meant that you could indeed put a different CPU in and I think they where supposed to be cheaper than a proper 486 etc. The main issue was the bus width and I think clock speeds? If you had the cash you were better off getting a proper 486.
Mind you the PS/2 machines were renowned for having custom bios stuff/hardware that broke the usual "standards" of the time. Same with compaq and I think HP. You could get many clone PCs that were running AMI or Phoenix bioses and they ran all the games and other software fine.
My recollection for the incompatibility were things like GFX(Their implementation of MDA/MCGA etc I think was a bit different),fonts and I think some internal DOS/BIOS/interrupt tables were different than the standard.
"Their implementation of MDA/MCGA etc I think was a bit different),fonts and I think some internal DOS/BIOS/interrupt tables were different than the standard."
Only IBM (on the 8086-based Model 25 and Model 30, and a couple derivative systems based on their planars) and the Epson Equity 1e used MCGA - and MCGA was never on a separate adapter. There are a couple fonts that changed with MCGA, and different versions of the IBM CGA adapter. And the IBM BIOS versions add more BIOS calls (like INT 15h, Function C9h for CPU information) than the clone manufacturers had in the CBIOS, and had the IBM-specific ABIOS section.
@IBM_Museum yeah my memory is vague with the differences but there were definately some incompatabilities and i know some of them were things like how the memory was layed out etc.
I had a model 30 xt version at one point and a couple of others later.
@@skilletpan5674: The 486SLC2 and 486SLC3 are clock doubled and tripled respectively, but are 16-bit external data bus and 24-bit address bus (meaning 16Mb of RAM maximum). The 486DLC2/486BL2 are 32-bit CPUs that are clock-doubled. Very different limitations.
Great video, never knew theses existed!
Thanks :) Neither did I! This IBM is nuts!
what a nice little odd ball you found there. now I wonder what else could be installed in its place? like any other cpus?
There's only one way to find out :)
19:40 Be EXTREMELY careful with that PLCC68 male socket, they are unobtanium now. The 486SLC is really just a 386sx with 16kB L1 cache and 486 instruction set but only has a 16-bit data bus so it's not a true 486. Performance will be somewhere between 386 and 486.
I forgot about the IBM 486 SLC chips. I built some clone PC's that used them back in the 1990's!
I threw so many into a skip when we upgraded at work.
What would make me suspicious (about it being a factory 486), is the absence of a CD-Rom drive.
And I guess, the badges would have been shipped with the upgrade kit.
I have finally managed to find one of the silly-rare external PS/2 drives for these machines :) It's in a pretty bad condition though so, we'll have to restore it in a video
Oh, I finally broke down and purchased a 3d printer. I found the Creality Ender 3 S1 Pro (the one to get if you're going 'cheap'. It was $187 BRAND NEW on eBay direct from Creality America.. As far as I'm concerned I STOLE this thing.. it has basically PAID for itself already, I have printed 2 clips to fix the handle on my refrigerator, a few other little things as well, but.. even with some accessories like a filament dryer, 6 kilos of filament (assorted flavors and colors) the enclosure (for temp and humidify control) a vacuum bag machine and bags.. you know, have to have all the goodies to go along with it, but I think I'm in under $400 with enough filament to last probably 6 months of printing. I am SO excited.. I can replace ALL the broken plastics from all my old machines now and do them correct, MYSELF. I am SO excited!!
That's awesome! At the moment I'm pretty happy that I can order free prints from a sponsor but looking forward to having my own printer in the future!
@AnthonyRBlacker - congratulations on your purchase.
I hope your supplies last six months. Seriously. Once you start printing, and designing and printing… consumables are consumed.
They are addictive because unlike most modern electronics, 3D printing involves a tinker element. You find you cannot leave them alone.
Good luck! It’s rewarding when you design something for work or home that has never existed before.
When someone sees a print in action as a functional tool and ask,”Where did you get this?” and you tell them that you printed it… people look at you differently.
It’s still a realm where some folks consider 3D printers to be a form of ‘witchcraft’ and a designer/maker to have supernatural skills.
I have two filament and two resin printers.
My friend has four printers. She cannot stop printing new stuff.
Good luck!
The only reason this works is because the 386SX was a drop-in for 286 chipset boards. and then tyhe 486SLC was a drop-in for that, all in the name of cost cutting. and in IBM's case, not so much.
Ah yes, nostalgia for the worst move IBM every made. MCA made the IBM PC not compatible with the IBM PC.
Interesting CPU adapter board.
Where did you get the production numbers for the computer ?
Wikipedia :)
I had a ALR Powerflex way back when. It was designed as a 286 that had a 386 or 486 daughter board that could be installed. When installed it disabled the onboard 286. I imagine that IBM utilized a similar concept here. As I remember though the performance was pretty limited compared to proper motherboard as there was a significant bottleneck to the memory.
If you install OS/2 17:32 version 2 on an IBM PS2 and connect a PS2 mouse while its running...the whole thing crashes.
Always liked the look of the PS/2. I still hope to add one to my collection someday.
I agree, they look great!
They used to make cpu accelerators for the Amiga in this style of board.
I'm about to start restoring my Amigas. I'll try to find interposers for them
I wonder if this cpu board would work in other PLCC based 286 systems?
We absolutely have to give it a try!
The 50Z I have does have vents on the side of the case
Yes, my 50z has vents on one side too. This machine has vent holes on both sides
Wow, this is gorgeous! I’m almost done with restoring a 50Z (also my first x86 PC) - I’m just really struggling finding a working 1.44MB floppy. Any chance you know someone who repairs them (I have several dead ones) or has spare working drives?
Now that I’ve finished watching the video, I see you did the floppy repair yourself. I’d be happy to hire your services to fix the drives I have if you’re interested.
Long story short, my project involves both a 50Z and a Model 70.
I’ve done a bunch of work to virtualize a Banyan VINES server and plan to use the 50Z and 70 as VINES clients.
Everything works except the floppy drive. I’ve got an emulator in place that let me install what I need to (including the Ethernet drivers) - but want to get a real floppy drive in place to make it 100% authentic.
Amazing machines that deserve restoration and preservation!
@@dmurphynj Sorry, I'm already working two full-time jobs so no chance to take on any repairs. You could check with your local vintage computer club. Hopefully, someone there could help you. Good luck with the project!
The lack of documentation on this "model" makes me think this must have been a localized upgrade offered by IBM only in specific international markets.
The badge does indicate to me this was an IBM-installed upgrade. I'm easily imagining some ads in local newspapers and magazines, and you had to bring in your machine to an authorized center for service, where the upgrade would be performed. As part of the upgrade, the badge on your case would be changed as well.
I'm guessing the upgrade would have been pretty expensive, and very few people did it, preferring to change their computer entirely instead.
Obviously this is all pure speculation, but this is the story/scenario that makes the most sense in my head.
IBM was licensed to use the 386SX codemask from Intel (hence the Intel copyright on the chip) with the limitation that the derived CPUs (386SLC, 496SLC2/486SLC3, and 486DLC2/486BL) only be used on IBM systems. I'm sure IBM charged a premium for installing this upgrade, although the IBM CE would come out to the customer premises as well for a business. Years ago, I was contacted by a (U.S.) power company that wanted to replace a failed diskette drive for a Model 50Z, and declined my offers to replace the entire system with something newer (it probably had an industrial microchannel adapter for monitoring, but I offered a PS/2 Model 77 as a substitute).
It could be a special bid unit that Ibm made for a company or organization. If you provide the numeric model number from the rear, might be able to find some information on it.
Thanks. The numbers at the back are : MH13762(N) and DN556689522
@@Epictronics1 it doesn't look like any Ibm model number that I'm familiar with. It should have type/model followed by the serial number.
i will say to this, my 286 back in the day, when i was kid, looked this, with holes on the side, the difference is on the front, where the floppy disk was, instead of the big hole you have for the botton, it had a small hole instead, so the floppy drive you had inside, looked original. i will say the 286 came from my moms work and got it in 94, idk if has something to do with design of the case.
My other Model 50s have vent holes on one side. This IBM has vent holes on both sides
I always mentally prepare myself for the exploding tantalums when watching videos about computers of this age.
The newest tant I have blown so far is from 1986. IBM PS/2s are ready to start blowing up any day now :)
@@Epictronics1: And systems that are stored away are more likely to develop the "whiskers" and have ambient humidity saturate the tantalums than electronics that are used...
I would assume this might have been a one off thing for certain markets and/or government agencies? Where did you acquire the machine?
Could be. This IBM came from Austria
Have a PS/2-30 286 ( from ~1988 ) which were upgraded with a similar Kingston 386SLC + ITT 387SX 25MHz daughter-board.
The PC was used to run Berkeley Spice.
The price/performance of CPU's dropped aggressively at the same time, so the upgrade was probably not worth it. 🙄
I have one of those, too. They're nice machines. I wasn't aware there were SLC interposers for them.
I really wish more SMD caps would PRINT THE VALUES ON TOP instead of obscure codes. WTF is an EFK 4CN? Just say 100 / 25V!
Our family had one of these back in the day (my Dad worked at IBM at the time). It always seemed a bit of an odd upgrade option even back in the day. Fortunately working at IBM at the time, I think he got a very good deal on the upgrade board and yes we had the 50z case at the time. Ours started off as a standard 286, then got a 386 upgrade (was a riser board which plugged into the 286 socket), then we upgraded to this board. While it was a "decent" upgrade at the time, certainly by the time we got ours, it was already nowhere near what was out there in the market. The 486SLC2/50 processor really wasn't that fast. The microchannel bus also continued to make the machine rather limiting at the time. The reality is we upgraded to a better machine quite quickly after that to get multimedia capability. An IBM PS/ValuePoint 486DX2/66, with sound card and CD-Rom, which itself was later upgraded with an Intel Pentium Overdrive 83Mhz chip.
You can put in a new combo FDD / HDD card