NASCOM
ROM
BASIC
Dis–Assembled
Part 3
By Carl Lloyd–Parker
Dis-assembly of NASCOM ROM BASIC Ver 4.7 PAGE 24
E668 FE20 PUTBUF: CP " " ; Is it a control code?
E66A DA10E6 JP C,MORINP ; Yes - Ignore
E66D 78 PUTCTL: LD A,B ; Get number of bytes in buffer
E66E FE49 CP 72+1 ; Test for line overflow
E670 3E07 LD A,CTRLG ; Set a bell
E672 D282E6 JP NC,OUTNBS ; Ring bell if buffer full
E675 79 LD A,C ; Get character
E676 71 LD (HL),C ; Save in buffer
E677 32CC10 LD (LSTBIN),A ; Save last input byte
E67A 23 INC HL ; Move up buffer
E67B 04 INC B ; Increment length
E67C CD9BE6 OUTIT: CALL OUTC ; Output the character entered
E67F C310E6 JP MORINP ; Get another character
E682 CD9BE6 OUTNBS: CALL OUTC ; Output bell and back over it
E685 3E08 LD A,BKSP ; Set back space
E687 C37CE6 JP OUTIT ; Output it and get more
E68A 7C CPDEHL: LD A,H ; Get H
E68B 92 SUB D ; Compare with D
E68C C0 RET NZ ; Different - Exit
E68D 7D LD A,L ; Get L
E68E 93 SUB E ; Compare with E
E68F C9 RET ; Return status
E690 7E CHKSYN: LD A,(HL) ; Check syntax of character
E691 E3 EX (SP),HL ; Address of test byte
E692 BE CP (HL) ; Same as in code string?
E693 23 INC HL ; Return address
E694 E3 EX (SP),HL ; Put it back
E695 CA36E8 JP Z,GETCHR ; Yes - Get next character
E698 C3ADE3 JP SNERR ; Different - ?SN Error