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t/data/zx81_version_2_rom_source.asm  view on Meta::CPAN

L048A:  CALL    L0A1F           ; routine LINE-ENDS
        LD      HL,($4014)      ; sv E_LINE_lo
        LD      (IY+$00),$FF    ; sv ERR_NR
        CALL    L0766           ; routine COPY-LINE
        BIT     7,(IY+$00)      ; sv ERR_NR
        JR      NZ,L04C1        ; to DISPLAY-6

        LD      A,($4022)       ; sv DF_SZ
        CP      $18             ;
        JR      NC,L04C1        ; to DISPLAY-6

        INC     A               ;
        LD      ($4022),A       ; sv DF_SZ
        LD      B,A             ;
        LD      C,$01           ;
        CALL    L0918           ; routine LOC-ADDR
        LD      D,H             ;
        LD      E,L             ;
        LD      A,(HL)          ;

;; FREE-LINE
L04B1:  DEC     HL              ;
        CP      (HL)            ;
        JR      NZ,L04B1        ; to FREE-LINE

        INC     HL              ;
        EX      DE,HL           ;
        LD      A,($4005)       ; sv RAMTOP_hi
        CP      $4D             ;
        CALL    C,L0A5D         ; routine RECLAIM-1
        JR      L048A           ; to EDIT-ROOM

; --------------------------
; THE 'WAIT FOR KEY' SECTION
; --------------------------
;
;

;; DISPLAY-6
L04C1:  LD      HL,$0000        ;
        LD      ($4018),HL      ; sv X_PTR_lo

        LD      HL,$403B        ; system variable CDFLAG
        BIT     7,(HL)          ;

        CALL    Z,L0229         ; routine DISPLAY-1

;; SLOW-DISP
L04CF:  BIT     0,(HL)          ;
        JR      Z,L04CF         ; to SLOW-DISP

        LD      BC,($4025)      ; sv LAST_K
        CALL    L0F4B           ; routine DEBOUNCE
        CALL    L07BD           ; routine DECODE

        JR      NC,L0472        ; back to LOWER

; -------------------------------
; THE 'KEYBOARD DECODING' SECTION
; -------------------------------
;   The decoded key value is in E and HL points to the position in the 
;   key table. D contains zero.

;; K-DECODE 
L04DF:  LD      A,($4006)       ; Fetch value of system variable MODE
        DEC     A               ; test the three values together

        JP      M,L0508         ; forward, if was zero, to FETCH-2

        JR      NZ,L04F7        ; forward, if was 2, to FETCH-1

;   The original value was one and is now zero.

        LD      ($4006),A       ; update the system variable MODE

        DEC     E               ; reduce E to range $00 - $7F
        LD      A,E             ; place in A
        SUB     $27             ; subtract 39 setting carry if range 00 - 38
        JR      C,L04F2         ; forward, if so, to FUNC-BASE

        LD      E,A             ; else set E to reduced value

;; FUNC-BASE
L04F2:  LD      HL,L00CC        ; address of K-FUNCT table for function keys.
        JR      L0505           ; forward to TABLE-ADD

; ---

;; FETCH-1
L04F7:  LD      A,(HL)          ;
        CP      $76             ;
        JR      Z,L052B         ; to K/L-KEY

        CP      $40             ;
        SET     7,A             ;
        JR      C,L051B         ; to ENTER

        LD      HL,$00C7        ; (expr reqd)

;; TABLE-ADD
L0505:  ADD     HL,DE           ;
        JR      L0515           ; to FETCH-3

; ---

;; FETCH-2
L0508:  LD      A,(HL)          ;
        BIT     2,(IY+$01)      ; sv FLAGS  - K or L mode ?
        JR      NZ,L0516        ; to TEST-CURS

        ADD     A,$C0           ;
        CP      $E6             ;
        JR      NC,L0516        ; to TEST-CURS

;; FETCH-3
L0515:  LD      A,(HL)          ;

;; TEST-CURS
L0516:  CP      $F0             ;
        JP      PE,L052D        ; to KEY-SORT