Py502

a Python CPU emulator with a custom instruction set, and an ASM compiler

What Doin'?

I am currently working on a C compiler for this custom CPU architecture. I am also going to add characters to my ASM compiler so you can do stuff like

message:
  .asciiz db "Hello, World!", 0x00 ; null terminated

Problem??

I've included a broken ASM program, try to fix it with the error messages from the compiler, and let me know where i can improve the messages


main:
    ldw a, 0xFF     ;  load 255 to A register, Unused
    str a, 0x0F      ;  will cause an error because its writing to program memory
                    ;  You will have to make the address bigger than the program
    int 0x00        ;  interupt to print a register to terminal as a char (debug)
    
    ldw a, 0        ; will be the graphics mode
    str a, 0xF0     ; copy A register to memory address   
    
    ldw a, 800      ; screen width
    str a, 0xF1     ; copy A register to memory address     
    
    ldw a, 600      ; screen height
    str a, 0xF2     ; copy A register to memory address
    jsr _init_graphics_mode
    
    
    
init_graphics_mode:
    push a
    push b
    push c
    
    ldw g, 0xFF ; This is never used
    
    ldr a, 0xF0 ; copy data from memory address to register 'A'
    ldr b, 0xF1 ; copy data from memory address to register 'B'
    ldr c, 0xF2 ; copy data from memory address to register 'C'
    
    int 0x70    ; all interupts in 0x70 - 0x7F are for graphics, 
                ; only 0x70 to 0x72 are implemented
                
    pop b
    pop a
    
    ret

Interupts

0x00 -> print register a as char 0x01 -> print register a as int 0xFF -> Halt 0xFE -> Error Interupt 0xF6 -> put keycode of currently pressed key in A register and but a value (bool)(0 or 1) into b register to indicate whether it is the first time this key has been pressed. 0x70 -> Init graphics, (A) mode (B) X resolution (C) Y Resulution 0x71 -> Set Pixel, (bitmap mode) (A) Color (0x000000 to 0xFFFFFF) (B) x position (C) y position 0x72 -> Set Char, (Text Mode) (A) Character Code (B) Cursor Position (C) Color (0x000000 to 0xFFFFFF)

! ALLL FILESYSTEM DRIVE NUMBER ARE LOCAL FILES ! drive( drive number (0 to 9)).bin "drive8.bin" drive number -> ( 0 to 9 ) sector number -> ( 0 to 15 ) byte offset -> ( 0 to 254 )

0x80 -> read byte from disk (A) drive number (B) sector number (C) byte offset moves output to A register 0x81 -> write byte from disk (A) drive number (B) sector number (C) byte offset (D) byte to write

2.9 KiB Raw Blame History

Py502

What Doin'?

Problem??

Interupts

Example error messages for the ASM Compiler

2.9 KiB

Raw Blame History