Difference between revisions of "6502 Counting Loop Example"
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START: | START: | ||
| − | + | JSR SCINIT ; Initialize and clear the screen | |
LDX #$00 ; Loop index (0-9) | LDX #$00 ; Loop index (0-9) | ||
| − | + | LINE: | |
TXA ; Put loop index into A | TXA ; Put loop index into A | ||
CLC | CLC | ||
| Line 16: | Line 16: | ||
LDY #$00 ; Character number to print | LDY #$00 ; Character number to print | ||
| − | + | CHARACTER: | |
LDA MSG,Y ; Get a character | LDA MSG,Y ; Get a character | ||
BEQ DONE ; Done if it's NULL | BEQ DONE ; Done if it's NULL | ||
JSR CHROUT ; Print character | JSR CHROUT ; Print character | ||
INY ; Increment char number | INY ; Increment char number | ||
| − | JMP | + | JMP CHARACTER ; Process next character |
DONE: | DONE: | ||
INX ; Increment loop index | INX ; Increment loop index | ||
CPX #10 ; Is it 10? | CPX #10 ; Is it 10? | ||
| − | BNE | + | BNE LINE ; If not, print next line |
BRK ; Stop | BRK ; Stop | ||
Latest revision as of 03:45, 18 December 2023
Here is a solution for part of the SPO600 64-bit Assembly Language Lab but implemented in 6502 Assembly language for use with the 6502 Emulator:
; ROM routines define SCINIT $ff81 define CHROUT $ffd2 START: JSR SCINIT ; Initialize and clear the screen LDX #$00 ; Loop index (0-9) LINE: TXA ; Put loop index into A CLC ADC #$30 ; Add $30 (ASCII '0') STA MSG_DIGIT ; Store into the string LDY #$00 ; Character number to print CHARACTER: LDA MSG,Y ; Get a character BEQ DONE ; Done if it's NULL JSR CHROUT ; Print character INY ; Increment char number JMP CHARACTER ; Process next character DONE: INX ; Increment loop index CPX #10 ; Is it 10? BNE LINE ; If not, print next line BRK ; Stop MSG: DCB "L","o","o","p",$20 MSG_DIGIT: DCB "#",$0D,$00 ; Note that MSG_DIGIT is a position in ; the middle of the message - not a ; separate message.
