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Keyboard BIOS AMIBIOS chip help

K

KLund1

Veteran Member
Joined
Jun 22, 2012
Messages
580
Location
Livermore, CA
Hi
I received this 386dx-40 board. It boots but has no keyboard input. As easily seen in the picture, the keyboard bios chip is bad. It is melted in the middle.
That chip label shows
AMIBIOS
AmericanMegatrends
Keyboard c1992
AA0105829

The retroweb has this board as unidentified, and no keyboard bios dump. (I'll upload good pics when I get this board working, and upload bios dumps when I get my minipro working again)

[Unknown] 386SI4

[Unknown] 386SI4 is a motherboard based on the SiS 85C460 (ISA 386DX/486 Single Chip) chipset. Get specs, BIOS, documentation and more!
theretroweb.com theretroweb.com

Any suggestions on replacing this bad keyboard BIOS chip?
 

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KLund1 said:
Any suggestions on replacing this bad keyboard BIOS chip?
Click to expand...
In the photo, I see "8042" printed beside the chip. So this chip, from a hardware perspective, is quite standard - an 8042 or 8742 (EPROM version of 8042) general purpose microcontroller that has been programmed with code that makes the 8042/8742 perform as a 'keyboard controller'. Same as what is done in the IBM AT (IBM 5170) - see [here].

There are people/companies at [here] that can supply and program 8042/8742. (I know, because I am one of them.)

The question is in what code to use. The code from the 8042/8742 used in the IBM AT has a reasonable chance of working on your motherboard. You can see by the 'self reminder' rows at [here], that a crude test shows that it basically works on some 386 and 486 motherboards of mine. Lacking would be PS/2 support (and more?)

Someone has probably already dumped the AMI code from the keyboard controller on a similarly dated motherboard of theirs.
 
My question is what caused the chip to smoke itself in case the replacement does the same. It sat there for quite a while as well.
 
Thanks,
I had a battery damaged 386 hat had a similar dated, same size keyboard chip. I swapped that in, and the board booted up and the keyboard works perfectly.
ALL good now.
I've lost count, but many thanks once again to modem7 !!! :)
 
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