Orange Micro Interface The Grappler - Manual (Page 11)

CUSTOM DRIVERS
If you are writing your own drivers the following locations are used
to access the card CY = NO where N = slot#)
Printer Status — $CØSl,Y (READ)
Output Latch - $CØ8l,Y (WRITE)
Strobe Low — $CØ82,Y (WRITE)
Strobe High — $CØ84,Y (WRITE)
The following routine gives an example of how to output a character
using these locations:
PHA ; SAVE OUTPUT CHARACTER ON STACK
LDY lØ ; SET UP Y-REGISTER FOR SLOT #1
PAPER? LDA $CØ8l,Y ; CHECK STATUS FOR PAPER
AND Ø4 ; CHECK SIT 2
BNE PAPER? ; IF SET THEN NO PAPER, RECHECK
SLCT? LDA $CØ8l,Y ; CHECK STATUS FOR PRINTER SELECT
AND Ø2 ; CHECK BIT 1
BEQ SLCT? ; IF ZERO THEN NOT SELECTED
BUSY? LDA $CØSl,Y ; CHECK STATUS FOR PRINTER BUSY
AND Ø8 ; CHECK BIT 3
BNE BUSY? ; IF SET THEN PRINTER IS BUSY
OUTPUT? PLA ; REGET OUTPUT CHARACTER
STA $CØ81,Y ; STORE TO OUTPUT LATCH
STA $CØ82,Y ; PULL STROBE LINE LOW
STA SCØ84,Y ; RESET STROBE LINE HIGH
RTS ; RETURN FROM SUBROUTINE
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