Instruction manual

fb3b c9 ret

fb3c ;

fb3c list: ;list character from register c

fb3c 79 LD a, c ;character to register a

fb3d c9 ret ;null subroutine

fb3e ;

fb3e listst: ;return list status (0 if not ready, 1 if ready)

fb3e af XOR a ;0 is always ok to return

fb3f c9 ret

fb40 ;

fb40 punch: ;punch character from register C

fb40 79 LD a, c ;character to register a

fb41 c9 ret ;null subroutine

fb42 ;

fb42 reader: ;reader character into register a from reader device

fb42 3e 1a LD a, 1ah ;enter end of file for now (replace later)

fb44 e6 7f AND 7fh ;remember to strip parity bit

fb46 c9 ret

fb47 ;

fb47 ; i/o drivers for the disk follow

fb47 ; for now, we will simply store the parameters away for use

fb47 ; in the read and write subroutines

fb47 ;

fb47 home: ;move to the track 00 position of current drive

fb47 ; translate this call into a settrk call with Parameter 00

fb47 0e 00 LD c, 0 ;select track 0

fb49 cd 66 fb call settrk

fb4c c9 ret ;we will move to 00 on first read/write

fb4d ;

fb4d seldsk: ;select disk given by register c

fb4d 21 00 00 LD HL, 0000h ;error return code

fb50 79 LD a, c

fb51 32 35 fc LD (diskno),A

fb54 fe 04 CP disks ;must be between 0 and 3

fb56 d0 RET NC ;no carry if 4, 5,...

fb57 ; disk number is in the proper range

fb57 ; defs 10 ;space for disk select

fb57 ; compute proper disk Parameter header address