IBM PS/2 Model 30-286 with massive upgrades and mods (pics!)

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IBM PS/2 Model 30-286 with massive upgrades and mods (pics!)

Postby nztdm » 2018-4-16 @ 15:18

Hello!

Thought I'd show off this build I've just finished stability testing.
I am very happy with it, and want to keep it. Will probably do so unless a generous enough buyer comes along.

Base: IBM PS/2 Model 30-286
From 31 years ago: 1987. My model was produced in 1989 though.

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Stock specs:
Intel 286 10MHz
0.5MB RAM (mine was maxed out with 4MB on the board when I got it)
30MB 3.5" Hard Drive (WDL-330P) (proprietary edge connector; unknown interface onboard)
1.44MB Floppy (proprietary header connector combining data and power)
Onboard 256KB VGA Graphics (this along with PS/2 ports is handyyyyy)
1 x 25-pin serial and 1 x parallel
3 x 16-bit ISA slots
PC-DOS Version ?.?

It came in pretty awesome condition. The power supply has zero dust which is weeeeird.
I love how compact this thing is for what it can hold!

First I repaired the 1.44MB proprietary floppy drive, as it had the common two leaking 10uF SMD electrolytic caps. Replaced those and worked perfect since.
Then I modified the DS1287 RTC chip to have a CR2032 holder on the top, as it was long dead.

I sourced a pile of 1MB Parity 9-chip 30-pin SIMMs, and a pair of 256KB 3-chip ones.
I then spent probably over 6 hours tediously modifying them to be PS/2 Compatible:
In case you don't know, IBM made the PS/2's that took 30-pin SIMMs, need special "IBM PS/2" versions. These were just regular SIMMs with a different pinout, and some unused pins used to identify the size.
So that was hours of fun with 0.25mm magnet wire and a magnifying glass.
You can find more details about the modifications here: https://www.vogons.org/viewtopic.php?f=46&t=59166
I made sure to only buy SIMMs where I can see all the traces and vias I need on the rear of the modules. This avoids doubling the tediousness by having to solder to the closely-packed chip legs on the front.

Upgraded specs:
Intel 287 FPU (toasty NOS ceramic version) because why not :-D
IBM Multifunction Adapter for Model 30-286:
> NOS, unopened box! It's lengthy and gorgeous~
> 1 x extra parallel port
> 1 x extra serial port (16450)
> 12 x 30-pin SIMM slots for up to 12MB Extended Memory (and tops base up to 640KB)
> > So total RAM became 12.5MB, as this expansion board requires "2 x 256KB only" on the motherboard.
> > Will sell the original 4 x 1MB genuine PS/2 SIMMs, as I'm using 100% counterfeit ones now :blush:
> > This takes a good couple minutes to do IBM's weirdly slow POST memory test with all 12.5MB to test. Luckily I turn off HIMEM's own test.
Accton EN1661 Ethernet Card:
> XT-IDE Universal BIOS (AT build, set for 16-bit IDE Interface at 170h/15) in boot ROM socket.
> > The config utility needs a 386, so this was configured in another machine, as the settings are saved in EEPROM.
> > Packet driver works perfectly, and this is my method for file transfer from main PC (220KB/s), and internet connection sharing :D
ESS ES1688 Sound Card:
> Jumpered config. Mixer utility works perfectly. No IDE jumpers.
> Has IDE port that is hard wired to 170h / IRQ15.
> Amplified output that isn't noisy. Rear volume wheel.
> PC speaker input. Motherboard has buzzer removed and routed to here instead (with a 1K resistor, reducing volume as the mixer has no PC-speaker volume option).
> Sounds damn good. Does SoundBlaster better than an actual Soundblaster. Built in OPL3 emulation is impressive on this.
512MB CF Card:
> In an IDE-CF adapter cabled to the sound card's IDE port.
> > Stealing 5V from two wavetable header pins.
> > IDE activity LED relocated to front window where the old 30MB HDD LED was; looks original!
> > Huge speed increase from the old 30MB drive. 1.5MB/s, 0.8ms.
> > Mounted the adapter on the original HDD sled.
Front speakers:
> Made use of the vent for the old hard drive and mounted a pair of 2W LCD-monitor speakers.
> Connected the speakers to the Normally-Closed pins of the sound card's output jack, via a soldered/glued 3-pin header underneath the sound card.
> > This means I get all sound card sound, as well as PC speaker, through decent front speakers, until I plug in external speakers, which will mute the front ones.
MS-DOS 6.22:
> mTCP
> Windows 3.1
> Norton Commander
> Assortment of games that run on this (Duke Nukem, Commander Keens, Jetpack, Secret Agent, Crystal Caves, Wolfenstein 3D if run in a small box)

Enjoy the pics!

FULL SIZE IMAGES HERE: https://imgur.com/a/I0zAs

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nztdm
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Re: IBM PS/2 Model 30-286 with massive upgrades and mods (pics!)

Postby pleonard » 2018-4-16 @ 15:38

Great work! The next level would be to buy an IBM PS/2 Speech Adapter, 3D-print the (never-shipped) internal mounting bracket for the front panel of a Model 30, and re-wire it to use the 'official' speaker. :)
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Re: IBM PS/2 Model 30-286 with massive upgrades and mods (pics!)

Postby luckybob » 2018-4-16 @ 22:18

Image

Sweet build! I love everything IBM!

So total RAM became 12.5MB, as this expansion board requires "2 x 256KB only" on the motherboard.


Are you sure about that? I was under the impression it can fill the 4mb-16mb range. Also are those 12 simms "normal"?

Third, what's with that mod on the left VLSI chip in the 8th image
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Re: IBM PS/2 Model 30-286 with massive upgrades and mods (pics!)

Postby nztdm » 2018-4-17 @ 01:57

luckybob wrote:Image

Sweet build! I love everything IBM!

So total RAM became 12.5MB, as this expansion board requires "2 x 256KB only" on the motherboard.


Are you sure about that? I was under the impression it can fill the 4mb-16mb range. Also are those 12 simms "normal"?

Third, what's with that mod on the left VLSI chip in the 8th image



Yes I'm sure.
I don't know why this is required.
It's stated in the manual and I tested it too.
The DIP siwtches select enable/disable serial/parallel ports, and the starting range of the memory (and whether you want to use some to top up base from 512KB to 640KB).
Starting address is any 0.5MB increment starting at 1MB.

The manual specifically states, to get a maximum of 15.5MB, you need two of these boards, with the second one filled with 256KB SIMMs to make 3MB.

=====

And no, this board is designed for this one system only, and only takes the PS/2 Type SIMMs, hence having to modify 12 of them.

=====

That mod to the VLSI chip is an undo to a previous mod to disable RAM waitstate. Was never stable, depsite the huge performance jump.
Also wasn't stable at 12MHz, even with a 16MHz rated 286, and the chipset being marked as 12MHz rated.
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Re: IBM PS/2 Model 30-286 with massive upgrades and mods (pics!)

Postby luckybob » 2018-4-17 @ 02:31

Well there are typically 2 reasons; "because fuck you thats why" and "some non-technical manager at IBM thought it was a 'good idea'. "

I have one, and 12x 512k simms for it. I only asked because your simms did not appear to be special.

that 0 WS mod sounds interesting. I'll have to look it up.

Any chance you want to mod like 16 more simms? I can't do it properly and you already have experience...
It is a mistake to think you can solve any major problems just with potatoes.
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Re: IBM PS/2 Model 30-286 with massive upgrades and mods (pics!)

Postby luckybob » 2018-4-17 @ 02:32

P.S.

I was under the impression the 3-chip ram isn't recommended for this mod for the model 30. maybe that was the real cause of the instability?
It is a mistake to think you can solve any major problems just with potatoes.
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Re: IBM PS/2 Model 30-286 with massive upgrades and mods (pics!)

Postby nztdm » 2018-4-17 @ 02:35

luckybob wrote:P.S.

I was under the impression the 3-chip ram isn't recommended for this mod for the model 30. maybe that was the real cause of the instability?


The 3-chip RAM is fine for 256KB modules.
Not for 1MB ones; the chipset doesn't support this high density.
Now, one thing I'm not sure on is whether the RAM board supports 3-chip 1MB; it does have its own lil memory controller in that neat metal chip...
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Re: IBM PS/2 Model 30-286 with massive upgrades and mods (pics!)

Postby nztdm » 2018-4-17 @ 02:46

luckybob wrote:Well there are typically 2 reasons; "because fuck you thats why" and "some non-technical manager at IBM thought it was a 'good idea'. "

I have one, and 12x 512k simms for it. I only asked because your simms did not appear to be special.

that 0 WS mod sounds interesting. I'll have to look it up.

Any chance you want to mod like 16 more simms? I can't do it properly and you already have experience...



Interesting. The manual says only 256KB and 1MB work in the expansion board.

The 0WS is unstable. I think it will be for everyone. Tried with many different RAMs including the chipset recommended 80ns.

I can make you 16. I need to source the right ones again.
Would be about $20 a pop if you bought that many. More if you wanted less.

I do have a bunch of leftover ones from various brands I could sell you for half price. They may or may not be stable together. I did not scientifically test. It may be due to some being dodgy, some being simply not compatible, or the board not liking you mixing different speeds and brands.

It now seems completely stable with 12 x identical SIEMENS 60ns modules.
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Re: IBM PS/2 Model 30-286 with massive upgrades and mods (pics!)

Postby Anonymous Coward » 2018-4-17 @ 06:38

One thing you didn't mention is that you replaced the CPU with a Harris 16MHz 286. Were you trying to do some overclocking?

Also, where are you guys getting those 12MB IBM RAM cards?
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Re: IBM PS/2 Model 30-286 with massive upgrades and mods (pics!)

Postby nztdm » 2018-4-17 @ 06:44

Anonymous Coward wrote:One thing you didn't mention is that you replaced the CPU with a Harris 16MHz 286. Were you trying to do some overclocking?

Also, where are you guys getting those 12MB IBM RAM cards?


Yea that was for testing 12MHz, which wasn't stable enough.
I left it in there because it runs wayyyy cooler than the original Intel 80286 10MHz.

It's not a 12MB IBM RAM card, it's an empty RAM card, that is only for the PS/2 Model 30-286. I swear the seller on eBay had two, but looks like they're gone.
It only becomes a 12MB card when you can find 12 x 1MB PS/2 SIMMs. These are damn near unobtanium. I modified regular SIMMs.
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Re: IBM PS/2 Model 30-286 with massive upgrades and mods (pics!)

Postby luckybob » 2018-4-17 @ 08:28

it also works on the IBM AT. IIRC. I've had mine for a few years. got it cheap because some of the slots had broken retention clips.

one of the 100's of little projects i have.
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Re: IBM PS/2 Model 30-286 with massive upgrades and mods (pics!)

Postby Anonymous Coward » 2018-4-18 @ 04:05

I really hate those angled SIMM slots with the crappy plastic retention clips. They always break. Are there any replacements with metal clips out there?

If you see anymore of those IBM memory boards, please let me know.
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