skx / z80-cpm-scripting-interpreter Goto Github PK

Suggest we use "M" to set the memory-address, "R"/"W" to allow reading/writing and use J to jump to new code.

• NOTE: This requires 16-bit temporary storage - #1

This would look like this:

3000M ; set the memory address to be 3000
c30W   ; write 30 to 3000
c40W   ; write 40 to 3001

c3000MJ  ; Jump to the code at address 3000

NOTE: We auto-increment the memory-address when (r)eading or (w)riting.

This is currently capped to 8-bit only.

Thinking about this we should also overhaul our I/O to read/write in hex only.

We use the CP/M bios for:

• Reading input into a buffer
• Writing a single character to the console.
• Writing a string to the console.

We should ensure we make it easy to swap those out, to ease porting to single-board computers that run standalone, without CP/M.

Something like this:

  ld IX, a_register
  ld h, (IX+0)
  ld l, (IX+1)

Is shorter than the indirect use we use right now.

It might also be worth thinking about register usage more generally; currently we go through a dance to preserve the contents of the string to interpret - which we keep in hl - but we don't do anything for the other registers which get juggled back and forth..