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t/data/zx81.ctl  view on Meta::CPAN

	:; update LAST_K with new values.
	:;

0248:C
0248 78         ld a, b	:C
	:; load A with previous column - will be $FF if
	:; there was no key.

0249:C
0249 C602       add a, $02	:C
	:; adding two will set carry if no previous key.
	:;

024B:C
024B ED42       sbc hl, bc	:C
	:; subtract with the carry the two key values.
	:;

024D:C
	:#; If the same key value has been returned twice then HL will be zero.
	:#
024D 3A2740     ld a, ($4027)	:C
	:; fetch system variable DEBOUNCE

0250:C
0250 B4         or h	:C
	:; and OR with both bytes of the difference

0251:C
0251 B5         or l	:C
	:; setting the zero flag for the upcoming branch.
	:;

0252:C
0252 58         ld e, b	:C
	:; transfer the column value to E

0253:C
0253 060B       ld b, $0B	:C
	:; and load B with eleven 
	:;

0255:C
0255 213B40     ld hl, $403B	:C
	:; address system variable CDFLAG

0258:C
0258 CB86       res 0, (hl)	:C
	:; reset the rightmost bit of CDFLAG

025A:C
025A 2008       jr nz, $0264	:C
	:; skip forward if debounce/diff >0 to NO-KEY
	:;

025C:C
025C CB7E       bit 7, (hl)	:C
	:; test compute and display bit of CDFLAG

025E:C
025E CBC6       set 0, (hl)	:C
	:; set the rightmost bit of CDFLAG.

0260:C
0260 C8         ret z	:C
	:; return if bit 7 indicated fast mode.
	:;

0261:C
0261 05         dec b	:C
	:; (4) decrement the counter.

0262:C
0262 00         nop	:C
	:; (4) Timing - 4 clock cycles. ??

0263:C
0263 37         scf	:C
	:; (4) Set Carry Flag
	:;

0264:C
	:#;; NO-KEY
0264 212740     ld hl, $4027	:C NO_KEY
	:; sv DEBOUNCE

0267:C
0267 3F         ccf	:C
	:; Complement Carry Flag

0268:C
0268 CB10       rl b	:C
	:; rotate left B picking up carry
	:;  C<-76543210<-C
	:;

026A:C
	:#;; LOOP-B
026A 10FE       djnz $026A	:C LOOP_B
	:; self-loop while B>0 to LOOP-B
	:;

026C:C
026C 46         ld b, (hl)	:C
	:; fetch value of DEBOUNCE to B

026D:C
026D 7B         ld a, e	:C
	:; transfer column value

026E:C
026E FEFE       cp $FE	:C
	:;

0270:C
0270 9F         sbc a, a	:C
	:;

0271:C
0271 061F       ld b, $1F	:C
	:;

t/data/zx81.ctl  view on Meta::CPAN

1CAC:B
1CAC-1CAC 00	:B
	:;;jump-true

1CAD:B
1CAD-1CAD 04	:B
	:;;to L1CB1, VALID
	:;

1CAE:B
1CAE-1CAE 34	:B
	:;;end-calc
	:;
	:;

1CAF:C
	:#;; REPORT-Ab
1CAF CF         rst $08	:C REPORT_Ab
	:; ERROR-1

1CB0:B
1CB0-1CB0 09	:B
	:; Error Report: Invalid argument
	:;

1CB1:B
	:#;; VALID
1CB1-1CB1 A0	:B VALID
	:;;stk-zero              Note. not 

1CB2:B
1CB2-1CB2 02	:B
	:;;delete                necessary.

1CB3:B
1CB3-1CB3 34	:B
	:;;end-calc

1CB4:C
1CB4 7E         ld a, (hl)	:C
	:;
	:;

1CB5:C
1CB5 3680       ld (hl), $80	:C
	:;

1CB7:C
1CB7 CD1D15     call $151D	:C
	:; routine STACK-A
	:;

1CBA:C
1CBA EF         rst $28	:C
	:;; FP-CALC

1CBB:B
1CBB-1CBB 30	:B
	:;;stk-data

1CBC:B
1CBC-1CBC 38	:B
	:;;Exponent: $88, Bytes: 1

1CBD:B
1CBD-1CBD 00	:B
	:;;(+00,+00,+00)

1CBE:B
1CBE-1CBE 03	:B
	:;;subtract

1CBF:B
1CBF-1CBF 01	:B
	:;;exchange

1CC0:B
1CC0-1CC0 2D	:B
	:;;duplicate

1CC1:B
1CC1-1CC1 30	:B
	:;;stk-data

1CC2:B
1CC2-1CC2 F0	:B
	:;;Exponent: $80, Bytes: 4

1CC3:B
1CC3-1CC6 4CCCCCCD	:B
	:;;

1CC7:B
1CC7-1CC7 03	:B
	:;;subtract

1CC8:B
1CC8-1CC8 33	:B
	:;;greater-0

1CC9:B
1CC9-1CC9 00	:B
	:;;jump-true

1CCA:B
1CCA-1CCA 08	:B
	:;;to L1CD2, GRE.8
	:;

1CCB:B
1CCB-1CCB 01	:B
	:;;exchange

1CCC:B
1CCC-1CCC A1	:B
	:;;stk-one

1CCD:B
1CCD-1CCD 03	:B
	:;;subtract

1CCE:B