The Nomad board is a 68000/68010 compatible microcomputer with 128K of SRAM and 128K of EEPROM memory, with the EEPROM being in a convenient PLCC socket for repeated removal.  The Nomad board includes a MK68901 peripheral chip to enable microcontroller-like functionality, including 4 timers, a buffered 115200 baud 8N1 UART interface, and an 8-bit I/O port, all with processor interrupt capabilities.  The board can be clocked anywhere from 8MHz (the minimum speed of the processor) to somewhere around 14MHz (max speed of the MK peripheral)

  The bootloader is currently not capable of self-updating, although this will be available in the future.  Due to the 68000 architecture, this means that the interrupt vector table is not modifiable without re-flashing the bootloader.  This can also be fixed by using a 68010, which can move the vector table into RAM if modification is required.

  On the software side, a couple programs have been developed in order to speed assembly development:

Design goals
    1. Fast.  Or at least as fast as the hardware will reliably support.
    2. Simple.  Easy to program for, but still capable of doing something interesting.
    3. Extensible.  The board should contain enough to do something fun out of the box, but not enough that it hinders future expansion.

    4. Compact.  I really don't like massive 2-layer boards, so this board is compact.

Bugs (version 1.0) (no, I didn't breadboard this beforehand)

  1. RX buffering is backwards
  2. All of the TX and RX signals are inverted
  3. RC values for reset are wrong
  4. 10uF caps have the wrong footprint
  5. Mounting holes were too small for decent-size standoffs
  6. The byte select signals for the SRAM and EEPROM are inverted, which was a pain to figure out because the 68000 still fetches instructions on word boundaries, so writing words or anything encoded in an instruction literal still worked.
  7. I think the 7805 is getting extra hot because I ran out of 0.1uF caps and had to use 0.33uF ones?

Known Issues

  1. Some of the silkscreens for the expansion IO connector are off a little
  2. Software Data Protection on the EEPROMs needs to be turned off for
    self-update functionality to work, but that isn't a huge concern and writing to EEPROM pairs with SDP enabled is extremely difficult to do with the current architecture.
  3. MFP DTACK signal is grounded all the time, but MFP still accepts reads
    and writes.  Doesn't cause any issues, but out of spec with the datasheet

Things that worked

  1. CPU executed code in a loop, RAM word access works well
  2. MFP can echo incoming strings over UART, and manipulate I/O ports
  3. Bootloader almost definitely works, but I haven't tested it yet.