1802 CPU for RC2014

The test ROM is now loading a boot block from the CF adapter and running it correctly. In theory that means we have everything needed to run ElfOS providing a paged RAM or banked memory card is used so the ROM can be banked out.

A hello world boot rom is now available in the RC2014 ROM github

Board config

- 16C550A UART at 0xC0

- 32K/32K RAM/ROM card with ROM in the low 32K

- SC129 at 0x80 for debug lights

- CPU card

I've also pushed fixes to the 1802 emulation and rc2014 1802 emulator to fix a bug in RET/DIS emulation where the documentation is misleading, and I've pushed the 1802 bug fixes the the assembler - which for other reasons is in the 6303 C compiler on my github.

The ROM source is probably mostly useful if you need the uart setup code to run with something more interesting like IDIOT or BASIC or perhaps you want to run it with 512K of banked RAM, a PPIDE disk interface and TMS991A video.. 8)

It lives.

Currently it's executing the first test program from ROM

    .abs
    .org    0

start:
    ldi    #0xFF
    phi    6
    ldi    #0x80
    plo    6
    ldi    #0xFF
    plo    8
loop:
    nop
    nop
    nop
    nop
    nop
    nop
    nop
    nop
    nop
    nop
    nop
    nop
    nop
    nop
    nop
    nop
    dec    7
    glo    7
    bnz    loop
    dec    8
    glo    8
    str    6
    br    loop

which is cycling LEDs on the debug card.

The configuration I am using at this point is a 32K/32K RAM/ROM card with ROM low, the 1802 CPU card, and an SC129 GPIO/Debug card. It's got a 16x50 UART plugged but in but I've yet to try and set that up.