UPD Modifications

Thanks to Peter McMullin, we now have a “Print an ASCII character” routine for the Centronics interface from EPROM Services in England. This can be patched into the “Universal Printer Driver” by entering the following code:

29D8~E5       ASCI PUSH HL
29D9 C5            PUSH BC
29DA F5            PUSH AF
29DB CDE702        CALL TFAS
29DE DB9B     STAT IN A.(9B)
29E0 17            RLA
29E1 38FB          JR C STAT
29E3 F1       SEND POP AF
29E4 D3BB          OUT (BB).A
29E6 AF            XOR A
29E7 D3BB          OUT (BB).A
29E9 AF            XOR A
29EA D3BB          OUT (BB).A
29EC DB9B          IN A.(9B)
29EE 17       BUSY RLA
29EF 3005          JR NC 29F6
29F1 17       ACK? RLA
29F2 3002          JR NC 29F6
29F4 18F6          JR 29EC
29F6 CD0702        CALL MDCK
29F9 C1            POP BC
29FA E1            POP HL
29FB C9            RET
29FC 00            NOP
29FD 00            NOP
29FE 00            NOP
29FF 00            NOP

Also, you have to add this little nine-byte initialization routine somewhere in memory (e.g. a 1 REM statement). Call this once, before printing, to initialize the PIO chip.

4082~3E88     INIT LD A.88
4084 D3BB          OUT (BB).A
4086 3E01          LD A.01
4088 D3BB          OUT (BB).A
408A C9            RET