Let There Be Light

A project log for Tiny020

A home-brew minimal 68020-based SBC

PlasmodePlasmode 01/16/2018 at 15:530 Comments

Added a pair of 7-segment displays to help me with debugging of software. The display is compatible with EASy68K hardware display trap 15/task 32, except there are only 2 displays instead of 8. Also implemented the ability to program the flash in-situ, so now I can reprogram the boot flash without removing it. I'm not putting away the flash programmer yet, just in case the newly programmed boot have fatal bugs and won't even boot. Tutor v1.3 will now run on Tiny020 using the existing trap service routines. Only a few modifications are needed: org the program to RAM base address ($100000 in this case); copy the trap #15 entry point from boot flash to RAM ($BC to $1000BC); and change vector base register to $100000. Tutor code is relocatable and with 68020's relocatable vector base register, it can be relocated and run anywhere. Very cool.

The next step is to revive my pc board layout tools so I can put this design in pc boards. I want to add the floating point coprocessor and include EASy68k hardware display as a permanent features of Tiny020, and it is too much work to hand-wire them.