PDA

View Full Version : Compaq SLT/286 RAM



Ben12345
April 25th, 2017, 10:28 PM
Hi Guys,

New member here, but a long passion for vintage computing, spanning from my childhood, when all as I had was old legacy hardware, until 1996 when my parents got me a brand new P75 system!

I recently acquired a dead SLT/286, along with an old Kodak portable printer. Physical condition is all pretty good, and i've just managed to get the SLT going by replacing all of the PSU electrolytics. Booted up fist time without a hint of a problem from the Dallas RTC! Second time, not so lucky... Insert diagnostic disc. Oh well, I knew it was inevitable. I'll have to get the dremel out.

Anyway, i'd like to stick Windows 3 on it eventually, but one problem. My system only has the base 640K ram. Does anybody have any leads on the odd looking P shaped Simms that plug into the expansion slots next to the LED board? I'd like my total memory to be at least 1 meg :)

Cheers,

Ben.

RWallmow
April 27th, 2017, 05:41 AM
Hi Guys,

New member here, but a long passion for vintage computing, spanning from my childhood, when all as I had was old legacy hardware, until 1996 when my parents got me a brand new P75 system!

I recently acquired a dead SLT/286, along with an old Kodak portable printer. Physical condition is all pretty good, and i've just managed to get the SLT going by replacing all of the PSU electrolytics. Booted up fist time without a hint of a problem from the Dallas RTC! Second time, not so lucky... Insert diagnostic disc. Oh well, I knew it was inevitable. I'll have to get the dremel out.

Anyway, i'd like to stick Windows 3 on it eventually, but one problem. My system only has the base 640K ram. Does anybody have any leads on the odd looking P shaped Simms that plug into the expansion slots next to the LED board? I'd like my total memory to be at least 1 meg :)

Cheers,

Ben.
Windows 3.0 will run on 640k though it's not the most useful that way. As far as finding memory, that's going to be tough, I went through a similar deal trying to find the proprietary memory expansion for my Compaq Portable II and Portable III, in the end with those I just installed ISA memory cards, sadly you can't go that route on a laptop :-/
If someone could find schematics for the memory slot, or if someone had a memory card they could provide schematics for, it would be possible to make your own memory card clone, since it probably just uses off the shelf DRAM chips.

Ben12345
April 27th, 2017, 08:29 AM
Hi,

Yes, now you mention about Windows 3 running on 640k, I seem to remember about 22 years ago putting it on an old Amstrad 286 PC clone with 640k, but struggled to get a serial mouse to work on it. Maybe I was thinking that 3.1 needed 1 meg?

This is what the memory looks like (I borrowed the photos from a website that I don't remember the address of). I was hoping that someone might have had some pulled from one they'd broken up for parts.

37984
37985

I'll keep hunting :)

moijk
April 28th, 2017, 10:02 AM
You don't by any chance have figured out the power supplys pinout? I got one but no psu. and frankly the web hasn't been helpful in that case.

Ben12345
May 4th, 2017, 10:43 AM
I did try to figure out the pinout, well pin-in of the internal DC-DC converter, but it didn't seem straightforward. I then had a brainwave and injected power into the machines battery terminals to find that my problem still persisted, which is when I decided to re-cap the internal DC-DC and external PSU.
I can have a go at measuring the power supply itself over the weekend sometime.

If you want to inject power into the battery terminals, from memory, the one on the far left (FDD side) is positive, and the far right (HDD side) is negative.

Ben12345
May 27th, 2017, 04:14 AM
Well I measured the output from the PSU, but didn't get any sensible values for you. I got 5v and 6v, but no 18v between any combination of pins. It seems that the 18v rail doesn't turn on until connected to the SLT, which makes it much harder to measure.

On a positive note, up popped three original SLT/286 1mb memory modules on ebay for a fair price, and they are here in the UK, so I had to buy them :) I pulled the trigger on an SLT/386 too. Not as good condition as my 286, but it's acceptable. All works too, other than the DC-DC supply needs re-capping and the 60mb hdd is a bit unhappy.

I also picked up a Victor V386PX, which looks like a clone of the SLT, but only 16Mhz.

Must stay away from ebay....

Casey
June 1st, 2017, 02:15 PM
How did you install a standard ISA card on the Portable III? Did you use the external expansion caddy?

RWallmow
June 1st, 2017, 04:44 PM
How did you install a standard ISA card on the Portable III? Did you use the external expansion caddy?
Yes, I have the ISA expansion chassis, 4mb ISA RAM card in one slot, network card in the other.