modem7,
Many thanks for the suggestions. To clarify, the boot of the system proceeds to the point that it attempts to boot from a floppy disk, which fails, because I do not have one connected. The long garbled beep seems to not affect POST.
I acquired (from Retro Innovation, thanks Jim!) a 27c64 and 2364 adapter, and programmed the Supersoft/Landmark BIOS, and got the following results:
- U34 8253 Timer Channel 2 failed, but only on 2nd pass
- Keyboard controller failed
- Keyboard scan lines passed
Since, according to the Supersoft manual, timer channel 2 has to do with sound generation, that probably explains my beep problem. I'll trace all the joints, as you suggested.
The keyboard, I'll have to check, as well. I, unfortunately, don't have a real PC/XT keyboard, but I breadboarded an XT/AT keyboard adapter, from the wiki, here. I'm not sure that it's completely working, but the keyboard LEDs do flash, during POST, and the pressing of any of the lock keys (caps, scroll and num) causes the appropriate LED to light, or go out, on the keyboard. I have one concern about assembly, when it comes to the keyboard. The two caps next to the keyboard connector are 3-holed, for 3-pin caps, and MTM supplied standard 2-pin MLCCs. The instructions for the standard decoupling caps, elsewhere on the board, specified that the caps should be installed to the center pin, and either one of the two outer pins. The keyboard caps, however, were not specified, and the only picture that I could find seemed to indicate that they were installed on the outer 2 pins, which is what I went with.
Thanks!
- Alex