VOGONS


First post, by Pabloz

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hello!
i have this very old 486 board. i am trying to use it but every time i boot i get the keyboard error. when i turn on the pc i see the cap lock key light for 1 sec then numlock one second but on this screen the keyboard has no light and does not respond to any of what the bios is telling you to hit.

i tried a multimeter and the traces are ok. i checked continuity from motherboard to the ps2 to Din adapter and there is continuity. im not sure what is going wrong. the bios looks very very old

the keyboard is a PS/2 keyboard with a din adapter

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the board is this one
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Reply 1 of 9, by CkRtech

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I own a couple of PS2 to AT adapters. One of them works fine with the couple of boards I have used it on. The other one does not. The faulty one doesn't work because despite the pin conversion, the outer ring wasn't grounded.

I can't remember the exact continuity check that failed, but I assume that there was no connection linking the outer ring of the AT side plug to the inner ring of the PS2 side plug in the adapter. It is possible your AT keyboard requires this connection for proper grounding, and your adapter isn't providing it.

Displaced Gamers (YouTube) - DOS Gaming Aspect Ratio - 320x200 || The History of 240p || Dithering on the Sega Genesis with Composite Video

Reply 2 of 9, by Pabloz

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CkRtech wrote:

I own a couple of PS2 to AT adapters. One of them works fine with the couple of boards I have used it on. The other one does not. The faulty one doesn't work because despite the pin conversion, the outer ring wasn't grounded.

I can't remember the exact continuity check that failed, but I assume that there was no connection linking the outer ring of the AT side plug to the inner ring of the PS2 side plug in the adapter. It is possible your AT keyboard requires this connection for proper grounding, and your adapter isn't providing it.

thanks for the advice, after reading it, i did more tests on my adapter cable pictured below.

1) Cable only: All the inner pins on one side of the cable have continuity to the other side of the cable.
2) Cable only: The Outer ring (orange) DOES NOT have continuity from one side to the other orange side on the cable.
3) Cable only: there is NO continuity between PIN4 ground, with outer rings Orange.
4) Cable + Motherboard: all the INNER pins on the cable also have continuity to motherboard contacts.

pin1: is clock
pin2: is data
pin3: is reset (not used)
pin4: Ground
pin5: 5v VCC

So what you are saying is that it can be solved by using a wire to connect both outer rings in organge?

Or using a cable to connect the outer ring orange to pin4 ground?

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Reply 5 of 9, by Pabloz

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i took another keyboard that was ps2 and connected it with the adaptar and it finally detected it and was able to setup the bios!!!!!!!!

I don´t know why this motherboard does not like my ibm MODEL M (SDL) modded with a ps2 cable

very of strange that award bios 4.20 is only 1 page, for example the screen says hit "page down" and "page up2 for other pages but that doesnt work, is award bios 4.20 only 1 page with such few options?

Reply 6 of 9, by Imperious

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Chances are Your IBM Model M keyboard is for an XT motherboard, which is not compatible with AT motherboards,
even though they use the same connector.

Atari 2600, TI994a, Vic20, c64, ZX Spectrum 128, Amstrad CPC464, Atari 65XE, Commodore Plus/4, Amiga 500
PC's from XT 8088, 486, Pentium MMX, K6, Athlon, P3, P4, 775, to current Ryzen 5600x.

Reply 8 of 9, by CkRtech

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Based on what I have read, the Model M keyboards draw a good amount of power. It is possible that your mobo doesn't provide the adequate power it needs.

Displaced Gamers (YouTube) - DOS Gaming Aspect Ratio - 320x200 || The History of 240p || Dithering on the Sega Genesis with Composite Video

Reply 9 of 9, by Pabloz

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CkRtech wrote:

Based on what I have read, the Model M keyboards draw a good amount of power. It is possible that your mobo doesn't provide the adequate power it needs.

probably this is the main reason
I got a model M very cheap and mint condition but it was DSL connector and the owner lost the cable.
So reading online i did a mod to it, soldered a PS2 extension cable and converted it into a PS2 model M

but the motherboard probably doesnt provide enough power, the model M works on a pcchips 486 motherboard tho.

the bios, my good, it was the first time i see a 1 page bios. 🤣