Hello Brian, > Thanks for the reply! It's a Commodore CBM 4032. When I turn it on, It > makes a shrill beeping sound for about a second then displays all the > correct bootup info. It also shows "ready>" at the bottom. Really "ready>" and not "ready."? The code for the ">" sign would be 0x3e, while "." is 0x2e. This could mean a failure in the memory chip connected to the processor's data line D4 (1 << 4 == 0x10). The chip probably has faulty bits also at other addresses, but luckily the system starts up pretty far nevertheless. > I opened it up and and probed the back of the keyboard connector with a > multimeter. When I press a key, the voltage will drop by a few tenths of a > volt. I don't think it's a problem with the keyboard. The keyboard lines are arranged in a matrix. If you really suspect the keyboard, you can measure the resistance between a row and a column line (disconnect the keyboard from the mainboard first) and press the corresponding key. The resistance sould be around 100 ohms (anyway less than 1 kilo-ohm). And if it really was a keyboard problem, I'd rather suspect the electronics that drives and reads out the keyboard matrix lines. I sent a copy to the cbm-hackers list, in case someone else has any ideas. You can send your further questions to the list address. Marko - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail firstname.lastname@example.org.
Archive generated by hypermail 2.1.1.