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Unknown 8088 motherboard.

R

redarrow

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Joined
Apr 26, 2008
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12
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South Africa
Hi,

I recently got hold of an old 8088 motherboard, which had been used in a specialised application, basically it had custom built cards with masses of input and outputs connected to it and it had a custom BIOS. No harddrive, keyboard, video card or anything else.

Now I already have one old 8088 system (my first personal PC :D) except that I blew the motherboard a long time ago. So I was hoping I'd be able to use this board to get it running again.

First thing I did was to simply insert a video card to see if it would output anything. It didn't.

I then wondered what would happen if I took the BIOS EEPROM from my blown motherboard and inserted it into this one. - To my surprise it appears to work! :D
The system display the BIOS version, performs a RAM check, at first the RAM check got stuck at 64k, but I then replaced the boards RAM microchips with some (not all) of the ones from my blown board and presto it gets past the RAM check. Right up to a whopping 256k. :D

The thing that doesn't work is the keyboard .. it simply gives me the message "KB error" (which is the message my old 8088 used to give on keyboard errors).
The first obvious thought I had was that the keyboard must be locked.. but I cannot find any jumpers on the board for the keyboard lock.. There aren't very many jumpers on the board at all so it wouldn't really be hard to find if it were marked.

I cannot think what else could cause the keyboard problem? Perhaps the system needs a keyboard controller chip or something? It is important to note that it did not have a keyboard in it's previous application so such a chip could perhaps have been removed (if it had one).

I even tried plugging in the Seagate harddrive controller card and harddrive from my old 8088 system and it detects the drive as it always used to.

I hope this isn't too much of a long winded story type problem.. I just wanted to explain the situation as best I could.. :)

So if anyone has any ideas I could try then that would be neat.. :)
I've uploaded a photo of the motherboard here: http://i11.photobucket.com/albums/a158/cgprogrammer/8088.jpg
I can try upload a higher resolution image if anyone wants a closer look.
 
Unless I'm mistaken, that's another version of this (check out solder pad placement where the parts don't match...the unused pads do match and many components do too...not exactly, but many, so I'd say a different revision of the same thing perhaps).

This helps little though since the board I have is marked "ALCO" and elsewhere "8MHZ TURBO BOARD". No info about this at all online. It's got a V20 on it.
 
Looks like a generic 256K Taiwanese clone to me--I probably have a manual for this board somewhere--not that it's going to tell you anything.

PC and XTs don't have a keyboard controller chip per se. Usually just a 74LS322 shift register feeding an 8255a. Check around the keyboard connector for cracked traces or cold solder joints. It's probably the angle of the photo, but U53 looks to be a bit oddly set in its socket.
 
Tell me how to rip the image and it's yours. If it would necessitate using a programmer of some sort, can't help you...don't have the needed tools. I'm also a bit stuck for bootable floppies since I don't have anything I can boot it from except my Juko D16-X IDE card...could put some stuff on the hard drive in another system then throw it in there.

The board works from my brief testing...hell, I'd even consider selling it if someone wanted it. I've presently got 3 working 8088 boards in the house (even if this one's a V20).

I think mine did need an XT keyboard but I don't recall exactly. I always use switchable ones for everything so it's easy for forget where I had the switch.
 
Thanks for all the replies.. :)

To be honest I'm not sure how you tell the difference between an AT and a XT keyboard .. they look much the same. I tried two different keyboards, the one is that which I used with my old 8088 system so it must be an XT keyboard. It has a toggle switch on the back allowing you to select between "X" and "A/P" (whatever that means) I do recall that it never worked with my system on one of those settings.. can't remember which though (I tried both now).

The keyboard plug is firmly soldered.. no crack marks or track breaks that I can see.

I'm wondering if the problem couldn't simply be due to the fact that the BIOS I'm using was not written for this board? The board I took it from is quite a bit different - more advanced I'd say, it has an onboard monochrome video output, floppy controller and a serial and parallel port.

Here's a (not too brilliant) picture of it: http://i11.photobucket.com/albums/a158/cgprogrammer/dtk8088-1.jpg
(Some parts have been unsoldered, after I blew it I butchered it a bit :oops: )


Something I'm thinking, that board has a jumper for the keyboard lock .. does it sound plausible that the BIOS "thinks" the keyboard is locked and that there is no way to unlock it because this board does not support that "feature"?

One other thing, as you can see in the picture, my blown board had two ROM BIOS chips.. I've only put one in the new board the second seems to do nothing no matter which ROM slot I put it into.
 
While 8088 motherboards with keyboard lock certainly existed, this doesn't appear to be one of them--you'd expect to see a labeled header somewhere where the lock could be plugged in. Is the 2-pin header near C3 at the rear of the board a reset switch connection point?

And yes, it could be the BIOS. Have you tried a plain-Jane IBM XT BIOS on it? If you'd like I can pass you a couple of clone BIOSes to try (assuming you've got an EPROM burner).

I do like this board--it's one of those that can be configured with 4 rows of 4164s or 2 rows of 41256 and 2 rows of 4164s to give 640K. Taiwanese cloning at its best.
 
The header near C3 is actually 3 pin, (the photo doesn't show it clearly) it's unmarked - I've no idea what it's for. Shorting out pins 1-2 does nothing (that I notice) shorting pins 2-3 doesn't allow the system to POST at all.

I'd love to try flash it with some different BIOSes, but I don't have an EPROM burner.. :(
Closest thing I have is a PIC programmer. :/
 
FWIW, here's something useful.

Hope they help. These were 'ripped' with mbruttman's PCJRCART (with the -dumprom switch)

I don't know how to view the contents of these or how to put them in a format suitable for a programmer or anything like that...if anyone has any other techniques for me to use please let me know (here, in public, such that others can see how to do it in the future).
 
Thanks kishy those might just come in useful :)
I'm pretty sure they're just binary files which could be dumped straight onto an EEPROM, they appear to be 64KB images, my EEPROM is only 8Kb, there does however seems to be a jumper to allow larger EEPROM's on the board..

Chuck(G) gave me a BIOS which I intend to try, I discovered a friend of mine has a programmer. I haven't paid him a visit yet though.
 
Just a further update, I tried Chuck(G)'s BIOS image, it boots up the system (well as far as it can get with no HDD), it doesn't report any keyboard errors, but the keyboard still does not work (Caps lock, Ctrl+Alt+Del, etc.. nothing has any effect).

I now suspect that my keyboard might be faulty or otherwise perhaps a hardware fault on the board.. :(

Time to locate another XT keyboard ... ;)
 
redarrow said:
Just a further update, I tried Chuck(G)'s BIOS image, it boots up the system (well as far as it can get with no HDD), it doesn't report any keyboard errors, but the keyboard still does not work (Caps lock, Ctrl+Alt+Del, etc.. nothing has any effect).

I now suspect that my keyboard might be faulty or otherwise perhaps a hardware fault on the board.. :(

Time to locate another XT keyboard ... ;)
Click to expand...

Do consider the possibility that it may use an AT keyboard (unless you already tried that).

Some late clone motherboards work with both (I think the Everex EV1601 I've got is one), some with exclusively AT, some still with exclusively XT. I think...THINK...that IBM's own PC/XT 286 used AT as well.
 
kishy said:
Do consider the possibility that it may use an AT keyboard (unless you already tried that).
Click to expand...
I tried that, it produced some garbage.. :eh:
At the moment if I connect the HDD then when the system boots up the Seagate BIOS comes up with a "Do you want to install this hardware: Y/N:" prompt .. with an AT keyboard plugged in, it outputs various random characters at this point (regardless of whether I'm typing anything or not).

I may be getting a new keyboard though (and possibly more!), I've gotten into contact with someone who has a collection of old parts and may or may not have an XT keyboard. :D
Going to go check it out tomorrow.. :D
 
redarrow said:
I tried that, it produced some garbage.. :eh:
At the moment if I connect the HDD then when the system boots up the Seagate BIOS comes up with a "Do you want to install this hardware: Y/N:" prompt .. with an AT keyboard plugged in, it outputs various random characters at this point (regardless of whether I'm typing anything or not).

I may be getting a new keyboard though (and possibly more!), I've gotten into contact with someone who has a collection of old parts and may or may not have an XT keyboard. :D
Going to go check it out tomorrow.. :D
Click to expand...

Yeah if it's generating garbage with an AT kb plugged in, chances are something's wrong with your XT one (it would be doing nothing if there were some inability to see any keyboard being connected)
 
Oh yeah, thought I'd provide this. It's the POST screen of my "8MHZ TURBO BOARD". Probably of no use because it has no identifying numbers on it, but whatever.
 

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I can now confirm that my keyboard is indeed faulty..
I got hold of two keyboards, one a really old XT only and the other one with the XT/AT switch.. :)

I also got a couple more HDD's, controller card and another almost complete 8088 system.. :D
 
An interesting point.. now that I've got a confirmed working keyboard, I thought I should retry the BIOS from my blown board .. the results: it no longer reports a keyboard error but the keyboard still doesn't work..

So a different BIOS was definitely needed as well.. ;)
 
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