BIOS Updates forum

I have two PC Chips M520 board - one works but BIOS displays "Keyboard error or no keyboard present" at POST. I desoldered the KBC and soldered socket there but the problem is the same with another KBC. Communication between KBC and keyboard is OK - the NumLock LED goes on/off when NumLock key is pressed.
The other board only beeps - same as if there's no memory installed.

Does anyone know how can these boards be fixed?

Rainbow wrote:I have two PC Chips M520 board - one works but BIOS displays "Keyboard error or no keyboard present" at POST.

Press F1 to continue ?

I desoldered the KBC and soldered socket there but the problem is the same with another KBC. Communication between KBC and keyboard is OK - the NumLock LED goes on/off when NumLock key is pressed.

(Long shot) Tried changing the A20 mode?
(Longer shot) Does this BIOS support exchange of K/b and PS/2 mouse ?

The other board only beeps - same as if there's no memory installed.

You've tried both SIMM and DIMM - checked for bent contacts, or debris in socket causing a short ?
and of course you've swapped the BIOS ROM?

Press F1 to continue ?

Keyboard does not work.

I have tried something more today: removed Flash ROM, put into my MS-5120 board. Saved BIOS, opened in MODBIN and changed defaults to halt on no error and boot from floppy. Then flashed and put back. The board now boots from floppy and HDD.

(Long shot) Tried changing the A20 mode?

Booting Windows 95 stops at HIMEM.SYS: Cannot control A20 line.

(Longer shot) Does this BIOS support exchange of K/b and PS/2 mouse ?

Most probably not because KB connector is DIN and mouse is PS/2. It does not support USB keyboard too.

Then took my old ALR Ranger notebook, ran Turbo Pascal and do some quick-and-dirty programming and testing of the KBC (ports.lst file from Ralf's Brown Interrupt List is great thing ), running the program first on the notebook and then on the M520. Reading the scancodes from the KBC returned always $FE (Resend: CPU to controller should resend last keyboard-command) or $FF (keydetection/overrun error).
The $AA command (initiate self-test) passed OK.
After sending $AB command to the KBC (initiate interface test), it returned $02 - keyboard clock line stuck high.
Using a multimeter, the clock line is really stuck high. It's OK on the second board. Maybe 74HC05A inverter is bad.

You've tried both SIMM and DIMM - checked for bent contacts, or debris in socket causing a short ?
and of course you've swapped the BIOS ROM?

I tried 128MB DIMM but it didn't work even in the working board. Tried 2 SIMMs in both banks. I tried swapping BIOS and RTC with the other board.

Downloaded the datasheet for the inverter - it's really bad. The input on pin 1 is high (5V) and the output pin 2 too - it should be inverted (0V). I'm going to replace it either with new one or with the one from the other board.

Rainbow wrote:Press F1 to continue?
Keyboard does not work.

Sorry, bad joke. That's what it usually says. "No keyboard - press F1 to continue"

It sounds as though you are making progress - good luck with replacing the inverter.

Replaced the inverter. The new one is DIP, the old one was SMD so there are now 14 wires sticking out of the board with the inverter on the top
Keyboard and PS/2 mouse works, played even Duke Nukem 3D But HIMEM.SYS still does not work: "Unable to control A20 line".

Rainbow, what is the chip markings of the SMD inverter on those boards?

Joe

M520 will take the 16-chip, 32MB DIMM, or the *special 64MB* ones that AJZ has . I have SIMMS in mine...4-16MB in one and 2-32MB in the other.

Good luck on the keyboard problem!!

It was 74HC05A, replaced with National Semiconductor MM74HCT05N.