Today I attended a repair workshop at System Source. I brought my XD88 and power supply that I had mostly repaired. I just needed to solder the remaining connections to the regulator. The first half of the repair happened in August 2023, and it’s been sitting on my bench since then. I finally took this oppourtunity to wrap it up. I’m happy to report that the power supply has been restored. I learned that if the fuse is blowing under no load it’s probably the bridge or the MOSFET(thank you Glitch!). Thank you CJ(fellow tek 88k fan) for the fuse.
Previously, I tried different combination of things to see if I could get serial console working, but was unsuccesful. This time I managed to get the cabling right and the baud rate at 38.4k and confirmed output from the serial port. There’s what’s called a peek-poke motinor on ROM and I was able to read and write data to memory. However the rom didn’t allow me to interactively boot the machine. When I set the dip switches to boot it would only boot and hang looking for the keyboard.
The machine is now ready for a boot image. If you have a boot disk image please let me know(michael dot kato at gmail). Thanks in advance.
firmware version 1.1 Tue Nov 21 10:01:12 PST 1989
printf exception handlers enabled
DISABLING CODE CACHEING
ENABLING CODE CACHEING
scan_for_display(0x80020000)- DISPLAY PRESENT
Display board tests
2-color mode address walk
2-color mode address-at-address
2-color mode mod-255
Packed-pixel mode patterns
Color pallette ram
2-color Mode Scroll Fill
1-color Mode Scroll Fill
VSYNC period= ~16msec
fault: kebyrd_init, sub-keybrd FRU-DISP/CE
timeout waiting for keybrd init