Difference between revisions of "6502 Counting Loop Example"
Chris Tyler (talk | contribs) |
Chris Tyler (talk | contribs) |
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| Line 9: | Line 9: | ||
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 | ||
Revision as of 02:00, 11 September 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.
