TOD8502z80

*=$1C01
        BYTE    $0B, $1C, $0A, $00, $9E, $37, $31, $38, $31, $00, $00, $00


        jmp 8502code

*=$1c10
z80code
          BYTE $3E,$3F,$32,$00,$FF,$21,$6D,$1C,$11,$4B,$2C,$01
          BYTE $03,$00,$ED,$B0,$01,$0B,$DC,$ED,$78,$0B,$ED,$60
          BYTE $0B,$ED,$68,$0B,$ED,$48,$4F,$11,$20,$2C,$CD,$48
          BYTE $1C,$1F,$3E,$3A,$38,$02,$3E,$20,$11,$22,$2C,$12
          BYTE $11,$25,$2C,$12,$C3,$E0,$FF,$00,$79,$CD,$62,$1C
          BYTE $79,$CD,$66,$1C,$13,$7C,$CD,$62,$1C,$7C,$CD,$66
          BYTE $1C,$13,$7D,$CD,$62,$1C,$7D,$C3,$66,$1C,$1F,$1F
          BYTE $1F,$1F,$E6,$0F,$F6,$30,$12,$13,$C9,$1A,$38,$30

; Lo z80 avvia la macchina; dopodiché attiva l'8502, e resta bloccato
; al punto in cui aveva eseguito l'attivazione dell'altro ($ffee).
; All'indirizzo $ffee va inserita un'istruzione JP di salto verso il
; codice z80 da eseguire
8502code
        sei
        lda $ff00
        pha
        lda #$c3        ; z80 "JP"
        sta $ffee
        lda #<z80code
        sta $ffef
        lda #>z80code
        sta $fff0

        lda #$3e        ; ram+ram+ram+io
        sta $ff00

        jsr ClearScreen

        lda #$0
        sta $dc08       ; start TOD

        lda $d018       ; MemScr -> $2c00
        pha
        and #$0f
        ora #$b0
        sta $d018

        ldx #$3         ; "8502" -> Video
lpcpu
        lda cpu,x
        sta $2c2a,x
        dex
        bpl lpcpu


lpZ80
;        lda #$3e        ; ram+ram+ram+io
;        sta $ff00
        lda #$b0
        sta $d505       ; -> z80
        nop

; qui è stato attivato lo z80; quando viene riattivato l'8502 il codice
; riparte da dove era rimasto bloccato


        ; z80 -> 8502
        ldx #0          ; TOD 8502
        lda $dc0b       ; HH
        jsr wb
        lda $dc0a       ; MM
        jsr wb
        lda $dc09       ; SS
        jsr wb
        lsr
        lda $dc08       ; restart TOD
        ldx #$3a        ; ":"
        bcc commas
        ldx #$20        ; " "
commas
        stx $2c02       ; " "|":" -> Video
        stx $2c05       ; " "|":" -> Video

WaitForSpace
        lda     #%11111111
        sta     $dc02
        lda     #%00000000
        sta     $dc03
        lda     #$7f    ;%01111111 - only row 7 KB matrix
        sta     $dc00

        lda     $dc01
        and     #$10    ;mask %00010000
        bne     lpZ80   ;

; ending
        pla
        sta $d018 ; MemScr -> $0400
        pla
        sta $ff00 ; MemConf -> iniz
        cli
        rts


cpu
       byte '8502'

;--------------------
wb      tay
        lsr
        lsr
        lsr
        lsr
        ora #$30
        sta $2c00,x
        tya
        and #$0f
        ora #$30
        inx
        sta $2c00,x
        inx
        inx
        rts

;--------------------
; (z80, $2c00)
ClearScreen
        ldx #250
        lda #$20
lpclr   sta $2c00-  1,x
        sta $2c00+249,x
        sta $2c00+499,x
        sta $2c00+749,x
        dex
        bne lpclr
        rts




; Note: Z80 uses IN and OUT to write to d000h-dfffh
; that's because that area is IO or Ram  depending on the direction port ($0001) of the 8502,
; and when z80 is active that port is disabled;
; so IN and OUT read/write the mapped IO, while LD reads/writes Ram


;.org 01c10h

;        LD A, 3Fh               ; ram+ram+ram+ram
;        LD (0FF00h),A
;
;        ld hl,cpu               ; "Z80" -> Video
;        ld de,02c4bh
;        ld bc,3h
;        ldir

;        ld bc,0dc0bh    ; TOD z80
;        in a,(C)                ; HH
;        dec bc
;        in h,(C)                ; MM
;        dec bc
;        in l,(C)                ; SS
;        dec bc
;        in c,(C)                ; restart TOD
;        ld c,a
;
;        ld de,02c20h
;
;        call Bcd2HexAscii
;        rra
;        ld a,3ah                ; ":"
;        jr c,commas
;        ld a,20h                ; " "
;commas
;        ld de,02c22h            ; " "|":" -> Video
;        ld (de),a
;        ld de,02c25h            ; " "|":" -> Video
;        ld (de),a

;        JP 0FFE0h               ; --> 8502
;        NOP



;ffe0  F3          DI
;ffe1  3E 3E       LD A, #$3E
;ffe3  32 00 FF    LD ($FF00),A
;ffe6  01 05 D5    LD BC, #$D505
;ffe9  3E B1       LD A, #$B1
;ffeb  ED 79       OUT BC,A
;ffed  00          NOP
;ffee  C3 3E 1C    JP $1C3E


;;;----------------------------------------------------
;;; Converts a 6-digit BCD number to a hex ASCII string
;;;
;;; input: DE = pointer to start of ASCII string
;;; C:HL number to be converted
;;; output: DE = pointer past end of ASCII string
;;; destroys: A,F,D,E
;;;-----------------------------------------------------
;Bcd2HexAscii
;        ;push de
;        LD A, C
;        CALL cvtUpperNibble
;        LD A, C
;        CALL cvtLowerNibble
;        inc de
;        LD A, H
;        CALL cvtUpperNibble
;        LD A, H
;        CALL cvtLowerNibble
;        inc de
;        LD A, L
;        CALL cvtUpperNibble
;        LD A, L
;        JP cvtLowerNibble
;

;cvtUpperNibble
;        RRA ; move upper nibble into lower nibble
;        RRA
;        RRA
;        RRA
;cvtLowerNibble
;        AND 0Fh         ; isolate lower nibble
;        OR 30h
;        LD (DE), A
;        INC DE
;        RET
;
;cpu
;        .db 01ah, "80"  ; "Z80"