Programming

My favorite test for ChatGPT is to ask it to write a function to divide two numbers in 6502 assembly. Not only is there no DIV instruction to rely on, but the 6502 is very register starved, so you get a lot of screwups. Here's one example of what ChatGPT generated:

; Inputs:
; - A: dividend
; - X: divisor

DIVISION:
    LDX #0       ; initialize quotient to 0
    CPX #0       ; check for divide-by-zero error
    BEQ DIVIDE_BY_ZERO
    CLC          ; clear carry flag
DIV_LOOP:
    CMP X,A      ; compare divisor with dividend
    BCC DIV_DONE ; if divisor is greater, division is complete
    SEC          ; set carry flag
    ROL A        ; shift dividend left
    INX          ; increment quotient
    JMP DIV_LOOP ; continue division
DIV_DONE:
    RTS          ; return from subroutine
DIVIDE_BY_ZERO:
    ; handle divide-by-zero error here
    RTS

You can see it immediately overwrites the divisor with the quotient, so this thing will always give a divide by zero error. But even if it didn't do that, CMP X,A is an invalid instruction. But even if that wasn't invalid, multiplying the dividend by two (and adding one) is nonsense.