RosettaCodeData/Task/Get-system-command-output/6502-Assembly/get-system-command-output.6502

JSR $FFED
;returns screen width in X and screen height in Y
dex     ;subtract 1. This is more useful for comparisons.
dey     ;subtract 1. This is more useful for comparisons.
stx $20 ;store in zero page ram
sty $21 ;store in zero page ram