Hi there,
I am trying to restore my old 286 motherboard Octek Fox II 286.
I still have the original SIMM RAM modules that used to work.
But now when I try to run the board via an ATX to AT adapter I get the following error message:
"INVALID SWITCH/ MEMORY FAILURE".
Do you think guys is something that can be fixed replacing the SIMM modules? Or could the problem be the motherboard itself?
Cheers,
Michele
Clean the edge contacts on the simms and try them again. Your switches may have corrosion. Also: Does your ATX PSU have a -5v line ? Most XT and 286 require +5v, +12v, -12v and -5v AFAIK. Also
Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun
Thanks for your reply Horun. I checked and the power supply has no -5 volt line. I'm gonna clean the SIMM modules contacts and try to check if the -5 volt is used by the SIMM.
You may also check if the ram had a parity chip and if parity is set in bios.
Stuck at 10MHz...
I think the SIMM have the parity chip. And the bios settings are lost because of the battery. So this might be the actual problem. I'm gonna check as soon as I get the ps/2 to AT adapter. Thanks a lot for the suggestion!
I tried to access the BIOS pressing either delete or esc keys without success, I can't enter the BIOS and instead I get the memory error.
I connected a speaker and without a VGA the BIOS makes 2 short beeps corresponding to parity check failure. With the VGA inserted instead I get 1 short beep meaning DRAM refresh failure.
I guess I need to replace the SIMM modules.
Ok. Sounds like bad ram but could also be a BIOS setting....
Curious which PS/2 keyboard you are using ? It seems you are trying to use adapters for PSU and also Keyboard which in itself is not the reason but one or both could be part of the symptom.
Not all PS2 keyboards are AT compatible, just like not all ps2 mice being serial compatible or visa-versa...
added: forgot to mention that even if you cannot enter the BIOS you should be able to do the Ctrl-Alt-Del and reboot the system with the ps2 KB and adapter (assuming standard BIOS).
If that does not work then most likely the KB is not being recognized. Do the LEDS on KB flash briefly ? If you hit Caps Lock or Scroll lock do the Led's lite up ? Hint if KB is recognixed...
Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun
Thanks for your answer Horun. It was a faulty RAM, I bought 2 new SIMM modules with parity bit and now everything works great including the keyboard.
Great ! Glad you got it working and is Good to know that the BIOS scans memory first before enabling keyboard. I have a Fox M286 or 286 M and it would probably react the same.....
Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun
Thank you very much for the help.
