Instruction manual

fb03 ;

fb03 01 80 00 LD BC, 80h ;default dma address is 80h

fb06 cd 77 fb call setdma

fb09 ;

fb09 fb ei ;enable the interrupt system

fb0a 3a 04 00 LD A,(cdisk) ;get current disk number

fb0d fe 04 cp disks ;see if valid disk number

fb0f da 14 fb jp c,diskok ;disk valid, go to ccp

fb12 3e 00 ld a,0 ;invalid disk, change to disk 0

fb14 4f diskok: LD c, a ;send to the ccp

fb15 c3 00 e4 JP ccp ;go to cp/m for further processing

fb18 ;

fb18 ; simple i/o handlers (must be filled in by user)

fb18 ; in each case, the entry point is provided, with space reserved

fb18 ; to insert your own code

fb18 ;

fb18 const: ;console status, return 0ffh if character ready, 00h if not

fb18 db 03 in a,(3) ;get status

fb1a e6 02 and 002h ;check RxRDY bit

fb1c ca 22 fb jp z,no_char

fb1f 3e ff ld a,0ffh ;char ready

fb21 c9 ret

fb22 3e 00 no_char: ld a,00h ;no char

fb24 c9 ret

fb25 ;

fb25 conin: ;console character into register a

fb25 db 03 in a,(3) ;get status

fb27 e6 02 and 002h ;check RxRDY bit

fb29 ca 25 fb jp z,conin ;loop until char ready

fb2c db 02 in a,(2) ;get char

fb2e e6 7f AND 7fh ;strip parity bit

fb30 c9 ret

fb31 ;

fb31 conout: ;console character output from register c

fb31 db 03 in a,(3)

fb33 e6 01 and 001h ;check TxRDY bit

fb35 ca 31 fb jp z,conout ;loop until port ready

fb38 79 ld a,c ;get the char

fb39 d3 02 out (2),a ;out to port