Z80 UART monitor
This ROM provides a small interactive monitor on the UART/CTC card at I/O base
20. Connect a terminal at 2400 baud, 8 data bits, no parity, 1 stop bit.
Commands are case-insensitive and all numeric arguments are hexadecimal; an
optional 0x prefix is accepted.
| Command | Action |
|---|---|
D 8000 |
Dump 40 bytes starting at address 8000 |
D 8000 20 |
Dump 20 bytes starting at address 8000 |
W 8000 3E 41 D3 25 C9 |
Write bytes starting at address 8000 |
I 20 |
Read I/O port 20 |
O 20 57 |
Write 57 to I/O port 20 |
G 8000 |
Execute code at address 8000 |
HELP |
Show the command summary |
G transfers control with a return address on the stack, so code ending in
RET returns to the monitor. Code that changes the stack pointer, interrupt
mode, or UART/CTC setup must restore it before returning.
Build the ROM and programmer-format images with:
make
The outputs are build/metal/monitor.bin (32 KiB ROM image) and
build/metal/monitor.prog.bin (compact programmer image).