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Need help for my newly acquired 8088

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First post, by Deksor

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Hi, I've just bought an 8088. It comes with a 5"1/4 floppy drive and a western digital hdd (with many many more things and other PCs that I'll probably show you later in the right topic) for 50€ in total. However as you may have guessed, it doesn't POST (at least it doesn't seem to since I don't have any monitor compatible with it. I've got 16bit ISA VGA cards though). The HDD is probably making a short circuit (tantalum capacitor ?) since the psu doesn't start at all when it is plugged. But it's fine when I disconect it.

I've tried my POST card, and here is what it does :
First the POST card doesn't show any code, but apparently every voltage are fine. Then the speaker makes a clicky sound and the card shows "FF". But this is the only thing that the computer does for now.

The floppy controller had an awful VARTA battery on it, and the second ISA slot had corrosion, so I've cleaned up a bit that slot with a toothbrush and vinegar. Now it should be fine, (the motherboard doesn't seem to be damaged anywhere else, even right next to the ISA slot). What could be the problem ?

Here are some photos from the machine :

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Reply 1 of 36, by Jo22

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FF is a good sign, it normally means that all operations succeeded.
The ticking sound usually occures when the system is counting the memory.
The floppy controller is an multi i/o card, I suppose. Its battery could be for the real-time clock then.
But I'm speaking under correction here, I'm no XT expert (still learning about this matter).

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

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Reply 2 of 36, by keropi

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You need to find a VGA that is compatible with 8bit mode, then we'll be able to figure things further

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Reply 3 of 36, by Jolaes76

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Take a look at your 16bit ISA VGA cards and try to find out if you have an 8 bit compatible one among them. Use Total Hw 99, vogons topics and vintage computer forums (vcfed.org) to get some help.
If there is a 8/16 jumper on a card then you have a good chance that the card will work in your XT. Not guaranteed, though. Some 16 bit VGAs work in the 8 bit AT slot but not in an 8 bit XT slot.
A Trident 8900C card, for example, should work in your motherboard.

Edit: got ninjaed by keropi 😀

"Ita in vita ut in lusu alae pessima iactura arte corrigenda est."

Reply 4 of 36, by Deksor

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Okay so I tried a trident video card ... and the PC is in fact counting the RAM !
I didn't knew it worked like that in 8088s

But the next problem is : my DIN keyboard isn't detected (the BIOS says "keyboard error") and so I can't do anything ...

This motherboard is in the AT form factor. But it seems that it's not compatible with AT keyboard. Am I right ?

EDIT : oh also this PC has a turbo mode. But oddly, in that mode at some point the picture disappears completely and I have to turn the computer off, wait for some time and turn it back on to have it working again. Is the PC overclocked so fast that it crashes ? 🤣
But I'm rather thinking that the PSU is becoming old

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Reply 5 of 36, by keropi

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^ the keyboard error could be because of the KEYLOCK feature , put a jumper in the pins on the mobo and try again

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Reply 6 of 36, by Deksor

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Doesn't work 😒

It must be the keyboard standard that isn't compatible with my AT style keyboard isn't it ?

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Reply 8 of 36, by Deksor

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Yeah, but I don't have any of those 🙁
Isn't there a way to create that around a simple microcontroller ? Like an Atmega328p ?

So this PC is working like an XT with an AT form factor, right ? What an odd PC ^^ (and I've found another motherboard that must be the same ^^)

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Reply 10 of 36, by keropi

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here you go, a design based on a PIC - works great: http://www.vcfed.org/forum/showthread.php?264 … board-converter
or CarlosTex, IIRC he has some for sale

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Reply 11 of 36, by Deksor

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I was saying that because I have a few spare atmega328P and an arduino to program them ^^

I've found this that may be what I'm looking for http://www.vcfed.org/forum/showthread.php?445 … to-XT-converter

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Reply 12 of 36, by Jo22

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If the PC would at least boot from A:> without key press, you could hook it up to another PC via a serial null-modem cable.
Just make a bootable floppy and add this line to autoexec.bat

CTTY AUX

..then you could use HyperTerminal (or similar terminal program) to access your XT's DOS prompt.
It works for DOS and for text-mode programs which use the DOS API for output.

I did such things many times when I was just a little kid.. ^^

Source: http://www.easydos.com/ctty.html

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

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Reply 13 of 36, by Deksor

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Sadly it hangs on the "keyboard error". And it seems that the VARTA killed the io card (I might be able to repair it though, it not too damaged I think. And there are probably only one trace layer per side)

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Reply 14 of 36, by Deksor

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So on the hdd side, i've disassembled the PCB but I've not seen anything that's really special. Nothing burned, nothing blown up ... But there is absolutely a short circuit somewhere

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Reply 15 of 36, by Jo22

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Are the HDD cables fine ?

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 16 of 36, by Deksor

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It doesn't even need to be plugged to the controller card.
Oh maybe you're talking about the wires coming from the inside of drive and that plugs into the pcb ? In that case, yes they are fine.

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Reply 17 of 36, by Deksor

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Now I cleaned a bit the io controller that had the leaky battery. When the computer is powered on, the floppy drive is spining and the controller doesn't prevent the computer to POST anymore. But it doesn't seem to be normal to me to have the floppy drive spining before the POST or without any floppy in the drive. There must be some damage left somewhere on that controller, but I don't know where. The computer seems to detect it though because it says that there is no bootable floppy inserted (so it may be able to boot even though there isn't any floppy inserted)

Here is the controller :

2016-11-12 13.01.09.jpg
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The chip in the middle, near the isa slot with a socket is a bit corroded. I replaced it's socket and did the best I could to clean it. It's a TIBPAL 16L8-25CN

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Reply 19 of 36, by Deksor

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Well this was the battery ^^
And the huge missing trace is the ground, and I checked with my multimeter, it's not disconnected

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