PC-9801VM error beeps on boot

Started by amigo-mexicano, May 23, 2021, 08:47:52 AM

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Hello guys, I have this PC-9801VM machine, was working fine, but then I tested the internal battery and instead of 3.6v, gave me a reading of 2.1v... so I tried to replace it, with a coin battery with the diode, and boom, 3 error beeps on boot. Two long beeps and one short. The machine boots to basic ROM, but when entering how many files, shows memory and no prompt (no response from keyboard at all, and does not boot any disk).

This model is the one that has dip switches instead of bios menu.

Switches were fine before, but anyway I tried to change them a bit (the one that saves the memory setup or checks every boot SW1-5) but no difference.

Also it caught my attention that all text now shows in green color, instead of white.

I tried to use keyboard combinations (HELP, HELP+RETURN, etc) and the machine ignores them.

I put back the original battery, but no difference, three beeps, boots and hangs upon entering to basic.

I already tried removing the cards one by one (floppy drive controller and a memory card), same error.

Does anyone know what does it mean two long beeps and one short, and if removing the original battery was the killing move?

Hope I can repair it.

Thanks in advance!
From Mexico City... Amigo-Mexicano!
Also known as: "compil3r" || video-juegos.com


OK, it's fixed!

I'll add the process, in case that someone gets here, looking for help on a similar case.

Turns out that I needed to setup again the machine using "SWITCH" program, that comes in any MS-DOS disk, in this case I used version 3.3B.

Turned off SW1-5 in order to "erase" ram setup on every boot. Then run SWITCH and setup my ram, in this case, it's 640KB. Saved setting on SWITCH, and turn on SW1-5.

Problem solved, now boots normally, no error beeps!

Seems that error beep code means that the ram is not configured. It would be nice to have a full reference of error beeps for PC-98, hope to find one someday.
From Mexico City... Amigo-Mexicano!
Also known as: "compil3r" || video-juegos.com