Thanks Chuck. It is disappointing to me some of the design choices made by IBM on some of this. They went through the trouble to define a new standard like VGA, why not do the same thing with the disk interface. To have such a variation of interfaces/pinouts between models seems a bit nuts though I get they were different price/performance levels.
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IBM ps/2 model 50
- Thread starter alank2
- Start date
Chuck(G)
25k Member
That's perhaps the biggest reason that I never was interested in acquiring a PS/2. Proprietary interfaces and peripherals mostly. Cosmetically, a nice design; easy to get into, but from a hardware standpoint, not so much.
Eudimorphodon
Veteran Member
My recollection is that there *is* an adapter to put DBA drives in the non-Z 50, but it might be hard to find because the upgrade version has ROMs on it while the 50z supported DBA drives in the system BIOS.
I would be ridiculously surprised if all four of those drives aren’t DBA, given their IBM house labeling. “Big” PS/2s with real ESDI drives had 5.25” bays for them.
Eudimorphodon
Veteran Member
I have strangely fond memories of what might be the most dirt-common PS/2, the 55sx. That cute little pizza box was *everywhere* in 1990. But your experience in this thread is why I’m never going to buy one.
(The rumor I keep hearing about them is that even if you find an unobtainium alternative storage device like a bootable SCSI card they still won’t work without a DBA drive plugged in.)
Chuck(G)
25k Member
And the question for IBM was always "why?". IBM had set a 16-bit industry standard with the 5170, which other vendors slavishly followed. ST506, SCSI and ESDI drive interface had already been standardized and the IDE interface wasn't far behind.
Eudimorphodon
Veteran Member
I think the answer is pretty obvious, which was they were sick of third parties eating their lunch, or at least their gravy. Almost from the day the original PC came out (and through the life of the 5170) it was completely SOP for third parties to lay hands on stripped down base-config IBM machines and resell them with cheaper third-party memory expansions, disk drives, etc. By making everything sickeningly proprietary I guess they figured they could recapture all that green because, of course, there's no way the market would respond by giving them a big fat middle finger and buying generic clones instead.
Chuck(G)
25k Member
Yeah, that's what I understand. Microchannel was patented and IBM wanted a fair amount of silver for a license. Those who opted to license it for competing systems were bitterly disappointed by the market.
Well MCA was a big step over ISA in terms on bandwidth and configuration of cards so it's not like they took ISA and changed the slot around. The competition gave IBM the finger and introduced EISA which few people bothered to use outside of servers anyway.
IBM did keep selling ISA based systems anyway like the PS/1.
There are a few third party SCSI cards for MCA.
IBM did keep selling ISA based systems anyway like the PS/1.
There are a few third party SCSI cards for MCA.
Eudimorphodon - so for the wide dba drives like in the auction above that I am getting, I would need a board like this:
ardent-tool.com
This section:
DBA-ESDI Adapter w/ ROM FRU P/N 90X9571, P/N 15F6993, 90X9570
8550 HDD Adapters
This section:
DBA-ESDI Adapter w/ ROM FRU P/N 90X9571, P/N 15F6993, 90X9570
Eudimorphodon
Veteran Member
Yeah, you need the "upgrade" adapter.
That page only specifically mentions it being offered with a 60MB hard drive upgrade. Hopefully the ROMs on it actually work with any DBA drive. (Knowing IBM I wouldn't bet much on it.)
That page only specifically mentions it being offered with a 60MB hard drive upgrade. Hopefully the ROMs on it actually work with any DBA drive. (Knowing IBM I wouldn't bet much on it.)
So my quest to get a working system continues. I got the seller of this to take $80 plus shipping for it:
I figure that between this and the 50 I have I should be able to fashion some thing together.
1. Extra floppy drive so I can do dual drives.
2. 50Z motherboard with the DBA riser for the drives I ordered.
3. Spare parts power supply / fan / etc.
IBM PS/2 Model 50 Type 8550 Vintage Computer As-Is | eBay
Unit powers on. No further testing done. Item may have internal missing/broken pieces not visible. Last 2 pictures are screenshots from when the unit was tested. Only what is pictured is included.
www.ebay.com
I figure that between this and the 50 I have I should be able to fashion some thing together.
1. Extra floppy drive so I can do dual drives.
2. 50Z motherboard with the DBA riser for the drives I ordered.
3. Spare parts power supply / fan / etc.
Chuck(G)
25k Member
I don't know, Alan. That "no further testing done" makes me a bit leery. After all, floppy drive failures on PS/2 systems are becoming legend. Well, it's a gamble and I hope it pays off for you.
I appreciate it Chuck. The screen showing it booting to the error was a little reassuring, so I'm hoping that means the motherboard is functional. The case I have is nice and clean, so I was thinking of swapping out the motherboard maybe with the case I have, but then maybe the 50z's case will clean up nice if I try. I'm okay if the floppy needs repair, I can replace caps so it won't be the end of the world if that turns into a repair project. Ultimately it would be nice to have a dual drive system with a working hard drive, but we'll see if I can get there with it!!
Eudimorphodon
Veteran Member
Yeah. I mean, hopefully you’ll luck out, but… I dunno, my spider sense is that whole stack of DBA drives you bought could be paperweights.
If you just wanted “a” PS/2 maybe it’d be worth looking for a 60 or 80 with their “regular” hard drive bay, or one of those later ones like a 56 or 57 with SCSI. But even then there’s so much to go wrong on them. :/
If you just wanted “a” PS/2 maybe it’d be worth looking for a 60 or 80 with their “regular” hard drive bay, or one of those later ones like a 56 or 57 with SCSI. But even then there’s so much to go wrong on them. :/
I love the PS/2s I have 10. My Model 50 has a working (when last tested) HDD and a dead FDD. I would never recommend someone get into them though. When I first got them in the early 2000s the drives were much less likely to be dead and parts were cheap. Now it's a different world. You really need spares to keep these systems going. I think you have the right idea, try to cobble together a working system from more than one system.
I recently looked into the chipsets of these things, and almost everything is a custom gate array with no documentation. A few chipset mfg. cloned the chipsets but i have yet to find out if they were used in any systems.
I don't know when IBM started work on the PS/2, '85 sounds about right. But the AT was doomed from the start. They crippled the speed to 6MHz, when 8MHz parts were available from Intel. There are dozens of articles in PC Mag/Infoworld/Byte explaining how to run it at 8MHz. The poor quality CMI HDD also screwed them on reliability. In '85 you could pay a premium for a 6MHz IBM with a HDD that could die at any moment, Or pay less, get 8MHz and a normal HDD. Yes you could say they lost control of the market with the first clones of the PC/XT, but these decisions with the AT really helped their decline. Think it was '86 when they finally got around to the 8MHz version. The PS/2 is often described as a failure and the AT as a success. In some ways though it was the AT standard (that went on for years), that was IBM's downfall. I read somewhere that while the PS/2 line didn't set the standard, it was a financial success for IBM.
I recently looked into the chipsets of these things, and almost everything is a custom gate array with no documentation. A few chipset mfg. cloned the chipsets but i have yet to find out if they were used in any systems.
I don't know when IBM started work on the PS/2, '85 sounds about right. But the AT was doomed from the start. They crippled the speed to 6MHz, when 8MHz parts were available from Intel. There are dozens of articles in PC Mag/Infoworld/Byte explaining how to run it at 8MHz. The poor quality CMI HDD also screwed them on reliability. In '85 you could pay a premium for a 6MHz IBM with a HDD that could die at any moment, Or pay less, get 8MHz and a normal HDD. Yes you could say they lost control of the market with the first clones of the PC/XT, but these decisions with the AT really helped their decline. Think it was '86 when they finally got around to the 8MHz version. The PS/2 is often described as a failure and the AT as a success. In some ways though it was the AT standard (that went on for years), that was IBM's downfall. I read somewhere that while the PS/2 line didn't set the standard, it was a financial success for IBM.
Chuck(G)
25k Member
Overclocking kits were a fairly popular business on the 5170s. You could just buy a set of crystals (run the thing faster until it doesn't) or if you wanted to be fancy, there were PLL-based variable oscillators that could be adjusted by means of a simple knob.
Eudimorphodon
Veteran Member
Something that’s a little frustrating is that several of the places that document PS/2 hardware mention a number of IDE adapter cards that were out there for the early models and go so far as listing out that the parts on the boards were all “generic“ TTL logic and PAL/GALs, but I haven’t found anyone trying to reverse engineer them. I mean, I know it’s likely that the PALs on these devices almost certainly had their read-protect bits set so getting the equations out of them would involve some more advanced and error-prone hackery, but if an open recreation of these things could come together it would be huge.
