The memory:

On top of the whopping 1 MB on board, we have this additional board - a Kingston KTC-1000s which supplies an additional 1 MB RAM and if documentation on the internet is anything to go by, it never existed at all. The pins are for additional memory modules (of which I am on the hunt for, the 4 MB modules preferably but I'd still take the 1 MB). One thing I notice compared to other compaqs is the sparse population of this board. All others seem absolutely chock full of ICs, but this one only has a sprinkle. It does the same job though so I shan't get too up in arms about it.

A quick look at the drive-bay cage with bios switch settings. One unusual thing with these bios switches is that the black dot corresponds not to what side the "light" (ie the fluorescent pink strip on the switch) needs to be visible, but to what side you need to press to get the correct setting. Turns out I had SW1 settings backwards for a while, Bessie never booted then either.

Moving back to the mainboard now, once the cage is removed we see the rest of the gubbins that make it work, along with what is causing me all this headache in the first place. That pesky dead DS1287. Luckily it's socketed so it just pops out. Time to install a shiny new DS12887.

Right so with the new DS12887 nestled nice and snug in the motherboard!

It's time to put Bessie back together and set up the bios using "Advanced Diagnostics". I downloaded the file from:
https://www.driverguide.com/driver/detail.php?driverid=73221

Which on my debian-based computer I injected into a floppy ima file mounted in a virtualbox instance that was running dos and could write directly to a 720k floppy disk. Of which I only owned one...

I hope it wasn't too valuable a game. It didn't seem to work anyway.

So lets reassemble! As I said, sadly the original floppy drive isn't working, so I had to make do until I can be bothered fitting a new one properly/repairing the old one.

AAAAAAAAAAAAAAND....

Bugger.

So who would have guessed. The DS12887 has a broken leg.

After pulling out the remnants of it from socket and making sure there no random little bits of metal left that could short something out, I figure I should make sure I haven't damaged anything. So dropping the original 1287 back in, I don't bother putting any of the original drives back in, I just want to make sure.

Sure enough, the board is fine, just the DS12887 was borked.

Oh well. Reassembling Bessie to await a new chip, instead of ordering another 12887, I'm going to give Maeslin's board a shot. I'd rather replace a coin cell than a full "black box" any day.

That memory card is interesting. I have one of these in my collection but didn't know what it was for. Mine is by Compaq not Kingston though. Can you post a photograph of the back side of it?

Do these cards only work in the Deskpro 386S?

Errius wrote:

Can you post a photograph of the back side of it? Do these cards only work in the Deskpro 386S?

I didn't include a photo of the back as there isn't a whole lot to see here. A few traces and the back side of the fingers.

The compaq is certainly the only computer I'm aware of that they work in, but I think it's a fairly standard ISA memory slot, so there are probably others. I see yours has the memory modules attached. If you're based in EU and are in the mood for selling for not-modern-GPU-cost level prices, I'd definitely be interested.

Do you know what the top edge connector is for?

I don't plan on selling right now but I'll let you know if I ever need to clear some space.

Errius wrote:

Do you know what the top edge connector is for?

I don't plan on selling right now but I'll let you know if I ever need to clear some space.

You know, honestly I was hoping someone could tell me what the top edge connector is for. It's like uber early SLI, but with RAM.

And fair enough! I'll keep my eyes on ebay for now then.

So I grew impatient. My DS12885 ICs from China are due to arrive some point... oh... mid October? So I want to see what I can work with just now.

So, investing in a nice shiny new 24 teeth-per-inch junior hacksaw blade, I decide to investigate exactly what's going on inside the DS1287. Having read (I think on the Vogon forums) that the 12887 is basically a 12885 with a crystal, battery, and a cap epoxied on, I decide the top of the cap is coming off. So folding the pins in so I don't break them, I get to work with my new hacksaw.

Turns out not only is the cap epoxied on, but the entire void is epoxy filled.

Right.

I know there's a battery in here somewhere though, so after an hour or so of sawing, then cracking bits off with a screwdriver I first uncover the battery, then clear enough space to crack it out.

Yup. It's just a button cell hiding the sneaky sneaky print on the IC... That says 1285. It's literally a 1285 with a battery and crystal (you can see the case for this poking out the left side of the chip) attached, filled with epoxy, then sold for 5x the price to take advantage of the fact it'll be the only chip to do the job its doing, while fitting that socket. Time to get a tabbed CR2032 from Amazon prime and see what I can do with this and some gaffer tape.

What do you mean this isn't the original chip?

However sadly this bodge didn't work, and upon removing it again the chip decided to slip and embed an entire row of pins into my finger. I have a rather decorative row of dots running up said finger now.

So not being patient enough to wait until October for the bits to arrive from China to build the DS12887 replacement, I dug out the broken DS12887 I received and decided to repair it. Just a broken pin and I had the broken bit. So I prepare my soldering bench. I prepare the pin for soldering, I prepare the IC for soldering. Then when lining the two up to solder, the tweezers promptly ping it across the room...

Glancing around however, I spy an enameled paperclip. I strip the enamel back to allow about 5mm bare. I snip it off and solder it on, trimming it back to the right length and giving it a good clean with IPA, it slots in and...

Woohoo!

So, the new question now is ... Do I stick with DOS 2.04 from 1984, or do I upgrade it to 6.22?

Go with Dos 5.x or 6.22. The 2.x is too old and might cause compatibility issues.

Cheers,

Vaudane wrote on 2018-08-03, 18:07:

The memory: 20180803_001444r.jpg On top of the whopping 1 MB on board, we have this additional board - a Kingston KTC-1000s whic […]
Show full quote

The memory:
20180803_001444r.jpg On top of the whopping 1 MB on board, we have this additional board - a Kingston KTC-1000s which supplies an additional 1 MB RAM and if documentation on the internet is anything to go by, it never existed at all. The pins are for additional memory modules (of which I am on the hunt for, the 4 MB modules preferably but I'd still take the 1 MB). One thing I notice compared to other compaqs is the sparse population of this board. All others seem absolutely chock full of ICs, but this one only has a sprinkle. It does the same job though so I shan't get too up in arms about it.

A quick look at the drive-bay cage with bios switch settings. One unusual thing with these bios switches is that the black dot corresponds not to what side the "light" (ie the fluorescent pink strip on the switch) needs to be visible, but to what side you need to press to get the correct setting. Turns out I had SW1 settings backwards for a while, Bessie never booted then either.
20180803_003025r.jpg
Moving back to the mainboard now, once the cage is removed we see the rest of the gubbins that make it work, along with what is causing me all this headache in the first place. That pesky dead DS1287. Luckily it's socketed so it just pops out. Time to install a shiny new DS12887.
20180803_001806r.jpg20180803_001933r.jpg20180803_002012r.jpg

Wanted to comment on your KTC-1000S expansion card. Noticed there are no PAL IC on yours, much easier to reproduce new expansion card clone since not have to decode that PAL programmable logic.
And can take either 1MB or 4MB on same board.

Can you tell me what are these 4 ICs that is around the memory chips?

Cheers,

pentiumspeed wrote on 2020-09-08, 15:24:

Wanted to comment on your KTC-1000S expansion card. Noticed there are no PAL IC on yours, much easier to reproduce new expans […]
Show full quote

Vaudane wrote on 2018-08-03, 18:07:

The memory: 20180803_001444r.jpg On top of the whopping 1 MB on board, we have this additional board - a Kingston KTC-1000s whic […]
Show full quote

The memory:
20180803_001444r.jpg On top of the whopping 1 MB on board, we have this additional board - a Kingston KTC-1000s which supplies an additional 1 MB RAM and if documentation on the internet is anything to go by, it never existed at all. The pins are for additional memory modules (of which I am on the hunt for, the 4 MB modules preferably but I'd still take the 1 MB). One thing I notice compared to other compaqs is the sparse population of this board. All others seem absolutely chock full of ICs, but this one only has a sprinkle. It does the same job though so I shan't get too up in arms about it.

A quick look at the drive-bay cage with bios switch settings. One unusual thing with these bios switches is that the black dot corresponds not to what side the "light" (ie the fluorescent pink strip on the switch) needs to be visible, but to what side you need to press to get the correct setting. Turns out I had SW1 settings backwards for a while, Bessie never booted then either.
20180803_003025r.jpg
Moving back to the mainboard now, once the cage is removed we see the rest of the gubbins that make it work, along with what is causing me all this headache in the first place. That pesky dead DS1287. Luckily it's socketed so it just pops out. Time to install a shiny new DS12887.
20180803_001806r.jpg20180803_001933r.jpg20180803_002012r.jpg

Wanted to comment on your KTC-1000S expansion card. Noticed there are no PAL IC on yours, much easier to reproduce new expansion card clone since not have to decode that PAL programmable logic.
And can take either 1MB or 4MB on same board.

Can you tell me what are these 4 ICs that is around the memory chips?

Cheers,

I'll dig out the board and let you know! Luckily, the memory board shown here is now in storage as I found a 4MB one with 2x1MB daughter boards (for a good price too!).

Vaudane wrote on 2018-08-03, 18:07:

The memory:
20180803_001444r.jpg On top of the whopping 1 MB on board, we have this additional board - a Kingston KTC-1000s which supplies an additional 1 MB RAM and if documentation on the internet is anything to go by, it never existed at all. The pins are for additional memory modules (of which I am on the hunt for, the 4 MB modules preferably but I'd still take the 1 MB). One thing I notice compared to other compaqs is the sparse population of this board. All others seem absolutely chock full of ICs, but this one only has a sprinkle. It does the same job though so I shan't get too up in arms about it.

I've just found a KTC-1000S in a box of cards I got from a haul of vintage computer stuff. Your post seems to be the only reference to this card on the internet! 😳 Before I shove it on eBay, is it of interest to you?