Cleanup & Add more comments
This commit is contained in:
Stefano Furiosi
parent
93be412fd7
commit
d2385a9d3f
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@ -0,0 +1,258 @@
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; dasm woz_monitor_masm.asm -orom.o -lrom.lst -srom.sym
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;-------------------------------------------------------------------------
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;
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; The WOZ Monitor for the Apple 1
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; Written by Steve Wozniak 1976
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;
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;-------------------------------------------------------------------------
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processor 6502
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org $FF00
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;-------------------------------------------------------------------------
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; Memory declaration
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;-------------------------------------------------------------------------
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XAML equ $24 ;Last "opened" location Low
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XAMH equ $25 ;Last "opened" location High
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STL equ $26 ;Store address Low
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STH equ $27 ;Store address High
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L equ $28 ;Hex value parsing Low
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H equ $29 ;Hex value parsing High
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YSAV equ $2A ;Used to see if hex value is given
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MODE equ $2B ;$00=XAM, $7F=STOR, $AE=BLOCK XAM
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IN equ $0200,$027F ;Input buffer
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KBD equ $D010 ;PIA.A keyboard input
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KBDCR equ $D011 ;PIA.A keyboard control register
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DSP equ $D012 ;PIA.B display output register
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DSPCR equ $D013 ;PIA.B display control register
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; KBD b7..b0 are inputs, b6..b0 is ASCII input, b7 is constant high
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; Programmed to respond to low to high KBD strobe
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; DSP b6..b0 are outputs, b7 is input
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; CB2 goes low when data is written, returns high when CB1 goes high
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; Interrupts are enabled, though not used. KBD can be jumpered to IRQ,
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; whereas DSP can be jumpered to NMI.
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;-------------------------------------------------------------------------
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; Constants
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;-------------------------------------------------------------------------
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BS equ $DF ;Backspace key, arrow left key
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CR equ $8D ;Carriage Return
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ESC equ $9B ;ESC key
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PROMPT equ $5C ;Prompt character \
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;-------------------------------------------------------------------------
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; Let's get started
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;
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; Remark the RESET routine is only to be entered by asserting the RESET
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; line of the system. This ensures that the data direction registers
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; are selected.
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;-------------------------------------------------------------------------
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RESET cld ;Clear decimal arithmetic mode
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cli
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ldy #%01111111 ;Mask for DSP data direction reg
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sty DSP ;(DDR mode is assumed after reset)
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lda #%10100111 ;KBD and DSP control register mask
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sta KBDCR ;Enable interrupts, set CA1, CB1 for
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sta DSPCR ;positive edge sense/output mode.
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; Program falls through to the GETLINE routine to save some program bytes
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; Please note that Y still holds $7F, which will cause an automatic Escape
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;-------------------------------------------------------------------------
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; The GETLINE process
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;-------------------------------------------------------------------------
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NOTCR cmp #BS ;Backspace key?
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beq BACKSPACE ;Yes
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cmp #ESC ;ESC?
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beq ESCAPE ;Yes
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iny ;Advance text index
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bpl NEXTCHAR ;Auto ESC if line longer than 127
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ESCAPE lda #PROMPT ;Print prompt character
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jsr ECHO ;Output it.
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GETLINE lda #CR ;Send CR
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jsr ECHO
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ldy #0+1 ;Start a new input line
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BACKSPACE dey ;Backup text index
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bmi GETLINE ;Oops, line's empty, reinitialize
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NEXTCHAR lda KBDCR ;Wait for key press
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bpl NEXTCHAR ;No key yet!
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lda KBD ;Load character. B7 should be '1'
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sta IN,Y ;Add to text buffer
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jsr ECHO ;Display character
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cmp #CR
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bne NOTCR ;It's not CR!
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; Line received, now let's parse it
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ldy #-1 ;Reset text index
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lda #0 ;Default mode is XAM
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tax ;X=0
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SETSTOR asl ;Leaves $7B if setting STOR mode
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SETMODE sta MODE ;Set mode flags
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BLSKIP iny ;Advance text index
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NEXTITEM lda IN,Y ;Get character
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cmp #CR
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beq GETLINE ;We're done if it's CR!
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cmp #"."
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bcc BLSKIP ;Ignore everything below "."!
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beq SETMODE ;Set BLOCK XAM mode ("." = $AE)
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cmp #":"
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beq SETSTOR ;Set STOR mode! $BA will become $7B
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cmp #"R"
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beq RUN ;Run the program! Forget the rest
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stx L ;Clear input value (X=0)
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stx H
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sty YSAV ;Save Y for comparison
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; Here we're trying to parse a new hex value
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NEXTHEX lda IN,Y ;Get character for hex test
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eor #$B0 ;Map digits to 0-9
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cmp #9+1 ;Is it a decimal digit?
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bcc DIG ;Yes!
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adc #$88 ;Map letter "A"-"F" to $FA-FF
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cmp #$FA ;Hex letter?
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bcc NOTHEX ;No! Character not hex
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DIG asl
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asl ;Hex digit to MSD of A
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asl
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asl
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ldx #4 ;Shift count
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HEXSHIFT asl ;Hex digit left, MSB to carry
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rol L ;Rotate into LSD
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rol H ;Rotate into MSD's
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dex ;Done 4 shifts?
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bne HEXSHIFT ;No, loop
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iny ;Advance text index
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bne NEXTHEX ;Always taken
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NOTHEX cpy YSAV ;Was at least 1 hex digit given?
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beq ESCAPE ;No! Ignore all, start from scratch
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bit MODE ;Test MODE byte
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bvc NOTSTOR ;B6=0 is STOR, 1 is XAM or BLOCK XAM
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; STOR mode, save LSD of new hex byte
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lda L ;LSD's of hex data
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sta (STL,X) ;Store current 'store index'(X=0)
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inc STL ;Increment store index.
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bne NEXTITEM ;No carry!
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inc STH ;Add carry to 'store index' high
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TONEXTITEM jmp NEXTITEM ;Get next command item.
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;-------------------------------------------------------------------------
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; RUN user's program from last opened location
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;-------------------------------------------------------------------------
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RUN jmp (XAML) ;Run user's program
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;-------------------------------------------------------------------------
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; We're not in Store mode
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;-------------------------------------------------------------------------
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NOTSTOR bmi XAMNEXT ;B7 = 0 for XAM, 1 for BLOCK XAM
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; We're in XAM mode now
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ldx #2 ;Copy 2 bytes
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SETADR lda L-1,X ;Copy hex data to
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sta STL-1,X ; 'store index'
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sta XAML-1,X ; and to 'XAM index'
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dex ;Next of 2 bytes
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bne SETADR ;Loop unless X = 0
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; Print address and data from this address, fall through next bne.
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NXTPRNT bne PRDATA ;NE means no address to print
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lda #CR ;Print CR first
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jsr ECHO
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lda XAMH ;Output high-order byte of address
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jsr PRBYTE
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lda XAML ;Output low-order byte of address
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jsr PRBYTE
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lda #":" ;Print colon
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jsr ECHO
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PRDATA lda #" " ;Print space
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jsr ECHO
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lda (XAML,X) ;Get data from address (X=0)
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jsr PRBYTE ;Output it in hex format
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XAMNEXT stx MODE ;0 -> MODE (XAM mode).
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lda XAML ;See if there's more to print
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cmp L
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lda XAMH
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sbc H
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bcs TONEXTITEM ;Not less! No more data to output
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inc XAML ;Increment 'examine index'
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bne MOD8CHK ;No carry!
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inc XAMH
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MOD8CHK lda XAML ;If address MOD 8 = 0 start new line
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and #%00000111
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bpl NXTPRNT ;Always taken.
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;-------------------------------------------------------------------------
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; Subroutine to print a byte in A in hex form (destructive)
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;-------------------------------------------------------------------------
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PRBYTE pha ;Save A for LSD
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lsr
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lsr
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lsr ;MSD to LSD position
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lsr
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jsr PRHEX ;Output hex digit
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pla ;Restore A
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; Fall through to print hex routine
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;-------------------------------------------------------------------------
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; Subroutine to print a hexadecimal digit
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;-------------------------------------------------------------------------
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PRHEX and #%00001111 ;Mask LSD for hex print
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ora #"0" ;Add "0"
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cmp #"9"+1 ;Is it a decimal digit?
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bcc ECHO ;Yes! output it
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adc #6 ;Add offset for letter A-F
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; Fall through to print routine
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;-------------------------------------------------------------------------
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; Subroutine to print a character to the terminal
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;-------------------------------------------------------------------------
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ECHO bit DSP ;DA bit (B7) cleared yet?
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bmi ECHO ;No! Wait for display ready
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sta DSP ;Output character. Sets DA
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rts
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;-------------------------------------------------------------------------
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; Vector area
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;-------------------------------------------------------------------------
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dc.w $0000 ;Unused, what a pity
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NMI_VEC dc.w $0F00 ;NMI vector
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RESET_VEC dc.w RESET ;RESET vector
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IRQ_VEC dc.w $0000 ;IRQ vector
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;-------------------------------------------------------------------------
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@ -1,258 +0,0 @@
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; dasm woz_monitor_masm.asm -orom.o -lrom.lst -srom.sym
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;-------------------------------------------------------------------------
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;
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; The WOZ Monitor for the Apple 1
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; Written by Steve Wozniak 1976
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;
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;-------------------------------------------------------------------------
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processor 6502
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org $FF00
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;-------------------------------------------------------------------------
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; Memory declaration
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;-------------------------------------------------------------------------
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XAML equ $24 ;Last "opened" location Low
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XAMH equ $25 ;Last "opened" location High
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STL equ $26 ;Store address Low
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STH equ $27 ;Store address High
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L equ $28 ;Hex value parsing Low
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H equ $29 ;Hex value parsing High
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YSAV equ $2A ;Used to see if hex value is given
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MODE equ $2B ;$00=XAM, $7F=STOR, $AE=BLOCK XAM
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IN equ $0200,$027F ;Input buffer
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KBD equ $D010 ;PIA.A keyboard input
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KBDCR equ $D011 ;PIA.A keyboard control register
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DSP equ $D012 ;PIA.B display output register
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DSPCR equ $D013 ;PIA.B display control register
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; KBD b7..b0 are inputs, b6..b0 is ASCII input, b7 is constant high
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; Programmed to respond to low to high KBD strobe
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; DSP b6..b0 are outputs, b7 is input
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; CB2 goes low when data is written, returns high when CB1 goes high
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; Interrupts are enabled, though not used. KBD can be jumpered to IRQ,
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; whereas DSP can be jumpered to NMI.
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;-------------------------------------------------------------------------
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; Constants
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;-------------------------------------------------------------------------
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BS equ $DF ;Backspace key, arrow left key
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CR equ $8D ;Carriage Return
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ESC equ $9B ;ESC key
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PROMPT equ "\" ;Prompt character
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;-------------------------------------------------------------------------
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; Let's get started
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;
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; Remark the RESET routine is only to be entered by asserting the RESET
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; line of the system. This ensures that the data direction registers
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; are selected.
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;-------------------------------------------------------------------------
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RESET CLD ;Clear decimal arithmetic mode
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CLI
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LDY #%01111111 ;Mask for DSP data direction reg
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STY DSP ;(DDR mode is assumed after reset)
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LDA #%10100111 ;KBD and DSP control register mask
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STA KBDCR ;Enable interrupts, set CA1, CB1 for
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STA DSPCR ;positive edge sense/output mode.
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; Program falls through to the GETLINE routine to save some program bytes
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; Please note that Y still holds $7F, which will cause an automatic Escape
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;-------------------------------------------------------------------------
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; The GETLINE process
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;-------------------------------------------------------------------------
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NOTCR CMP #BS ;Backspace key?
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BEQ BACKSPACE ;Yes
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CMP #ESC ;ESC?
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BEQ ESCAPE ;Yes
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INY ;Advance text index
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BPL NEXTCHAR ;Auto ESC if line longer than 127
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ESCAPE LDA #PROMPT ;Print prompt character
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JSR ECHO ;Output it.
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GETLINE LDA #CR ;Send CR
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JSR ECHO
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LDY #0+1 ;Start a new input line
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BACKSPACE DEY ;Backup text index
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BMI GETLINE ;Oops, line's empty, reinitialize
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NEXTCHAR LDA KBDCR ;Wait for key press
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BPL NEXTCHAR ;No key yet!
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LDA KBD ;Load character. B7 should be '1'
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STA IN,Y ;Add to text buffer
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JSR ECHO ;Display character
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CMP #CR
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BNE NOTCR ;It's not CR!
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; Line received, now let's parse it
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LDY #-1 ;Reset text index
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LDA #0 ;Default mode is XAM
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TAX ;X=0
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SETSTOR ASL ;Leaves $7B if setting STOR mode
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SETMODE STA MODE ;Set mode flags
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BLSKIP INY ;Advance text index
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NEXTITEM LDA IN,Y ;Get character
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CMP #CR
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BEQ GETLINE ;We're done if it's CR!
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CMP #"."
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BCC BLSKIP ;Ignore everything below "."!
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BEQ SETMODE ;Set BLOCK XAM mode ("." = $AE)
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CMP #":"
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BEQ SETSTOR ;Set STOR mode! $BA will become $7B
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CMP #"R"
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BEQ RUN ;Run the program! Forget the rest
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STX L ;Clear input value (X=0)
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STX H
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STY YSAV ;Save Y for comparison
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; Here we're trying to parse a new hex value
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NEXTHEX LDA IN,Y ;Get character for hex test
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EOR #$B0 ;Map digits to 0-9
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CMP #9+1 ;Is it a decimal digit?
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BCC DIG ;Yes!
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ADC #$88 ;Map letter "A"-"F" to $FA-FF
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CMP #$FA ;Hex letter?
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BCC NOTHEX ;No! Character not hex
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DIG ASL
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ASL ;Hex digit to MSD of A
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ASL
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ASL
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LDX #4 ;Shift count
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HEXSHIFT ASL ;Hex digit left, MSB to carry
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ROL L ;Rotate into LSD
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ROL H ;Rotate into MSD's
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DEX ;Done 4 shifts?
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BNE HEXSHIFT ;No, loop
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INY ;Advance text index
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BNE NEXTHEX ;Always taken
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NOTHEX CPY YSAV ;Was at least 1 hex digit given?
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BEQ ESCAPE ;No! Ignore all, start from scratch
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BIT MODE ;Test MODE byte
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BVC NOTSTOR ;B6=0 is STOR, 1 is XAM or BLOCK XAM
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; STOR mode, save LSD of new hex byte
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LDA L ;LSD's of hex data
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STA (STL,X) ;Store current 'store index'(X=0)
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INC STL ;Increment store index.
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BNE NEXTITEM ;No carry!
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INC STH ;Add carry to 'store index' high
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TONEXTITEM JMP NEXTITEM ;Get next command item.
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;-------------------------------------------------------------------------
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; RUN user's program from last opened location
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;-------------------------------------------------------------------------
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RUN JMP (XAML) ;Run user's program
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;-------------------------------------------------------------------------
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; We're not in Store mode
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;-------------------------------------------------------------------------
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NOTSTOR BMI XAMNEXT ;B7 = 0 for XAM, 1 for BLOCK XAM
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; We're in XAM mode now
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LDX #2 ;Copy 2 bytes
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SETADR LDA L-1,X ;Copy hex data to
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STA STL-1,X ; 'store index'
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STA XAML-1,X ; and to 'XAM index'
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DEX ;Next of 2 bytes
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BNE SETADR ;Loop unless X = 0
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; Print address and data from this address, fall through next BNE.
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NXTPRNT BNE PRDATA ;NE means no address to print
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LDA #CR ;Print CR first
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JSR ECHO
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LDA XAMH ;Output high-order byte of address
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JSR PRBYTE
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LDA XAML ;Output low-order byte of address
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JSR PRBYTE
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LDA #":" ;Print colon
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JSR ECHO
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PRDATA LDA #" " ;Print space
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JSR ECHO
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LDA (XAML,X) ;Get data from address (X=0)
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JSR PRBYTE ;Output it in hex format
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XAMNEXT STX MODE ;0 -> MODE (XAM mode).
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LDA XAML ;See if there's more to print
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CMP L
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LDA XAMH
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SBC H
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BCS TONEXTITEM ;Not less! No more data to output
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INC XAML ;Increment 'examine index'
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BNE MOD8CHK ;No carry!
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INC XAMH
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MOD8CHK LDA XAML ;If address MOD 8 = 0 start new line
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AND #%00000111
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BPL NXTPRNT ;Always taken.
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;-------------------------------------------------------------------------
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; Subroutine to print a byte in A in hex form (destructive)
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;-------------------------------------------------------------------------
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PRBYTE PHA ;Save A for LSD
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LSR
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LSR
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LSR ;MSD to LSD position
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LSR
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JSR PRHEX ;Output hex digit
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PLA ;Restore A
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; Fall through to print hex routine
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;-------------------------------------------------------------------------
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; Subroutine to print a hexadecimal digit
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;-------------------------------------------------------------------------
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PRHEX AND #%00001111 ;Mask LSD for hex print
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ORA #"0" ;Add "0"
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CMP #"9"+1 ;Is it a decimal digit?
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BCC ECHO ;Yes! output it
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ADC #6 ;Add offset for letter A-F
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; Fall through to print routine
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;-------------------------------------------------------------------------
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; Subroutine to print a character to the terminal
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;-------------------------------------------------------------------------
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ECHO BIT DSP ;DA bit (B7) cleared yet?
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BMI ECHO ;No! Wait for display ready
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STA DSP ;Output character. Sets DA
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RTS
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;-------------------------------------------------------------------------
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||||
; Vector area
|
||||
;-------------------------------------------------------------------------
|
||||
|
||||
dc.w $0000 ;Unused, what a pity
|
||||
NMI_VEC dc.w $0F00 ;NMI vector
|
||||
RESET_VEC dc.w RESET ;RESET vector
|
||||
IRQ_VEC dc.w $0000 ;IRQ vector
|
||||
|
||||
;-------------------------------------------------------------------------
|
||||
|
|
@ -10,13 +10,13 @@ The project is build over Platformio (http://platformio.org/frameworks) but you
|
|||
## How it works
|
||||
A 65C02S (modern version of the original 6502) is wired on a breadboard. The 6502 is a very simple kind of CPU in terms of I/O and the modern version allow us to suspend the clock at any time in LOW / HIGH state.
|
||||
|
||||
There are 16 Address Pins (A0-A15) each mapping a bit (HIGH/LOW) of an address word. This is how 6502 tell us what address he want to read or write to (RAM/ROM, IO dedicated address spaces). The state of this pins may change at every clock cycle.
|
||||
There are 16 Address Pins (A0-A15) each mapping a bit (HIGH/LOW) of an address word. This is how 6502 tell us which address he want to read or write to (RAM/ROM, IO dedicated address spaces). The state of this pins may change at every clock cycle.
|
||||
|
||||
Other 8 pins will carry or expect the 1 Byte data to be stored or read to / from the address above.
|
||||
|
||||
The CPU tell the external world if the data is in read or write state via R/W pin (HIGH=Expect data IN, LOW=Send data OUT).
|
||||
|
||||
This is it. This is all you need to interact with a 6502. The CPU expect a clock signal (HIGH/LOW) on pin 37 (PHI2). The modern version of 6502 is able to suspend any activity for an unlimited period of time during a clock cycle, both in LOW or HIGH state (was a little bit more hard with the original CPU). This make a perfect fit to let us drive the CPU via something different from a crystal, in our case, an Arduino, debug any single clock cycle and keep things in sync.
|
||||
That's it. This is all you need to interact with a 6502. The CPU expect a clock signal (HIGH/LOW) on pin 37 (PHI2). The modern version of 6502 is able to suspend any activity for an unlimited period of time during a clock cycle, both in LOW or HIGH state (was a little bit more hard with the original CPU). This make a perfect fit to let us drive the CPU via something different from a crystal, in our case, an Arduino, debug any single clock cycle and keep things in sync.
|
||||
|
||||
Knowing the address space where the Apple 1 was mapping the different IO (Ram / ROM / KEYB / DSP), we can simulate the external interfaces (in fact a PIA 6821) and send back & forth as needed the related data via 6502 data bus. That's it.
|
||||
|
||||
|
|
@ -53,8 +53,11 @@ The WOZ monitor asm source and the original apple 1 operation manual are two ver
|
|||
+--------------+ |
|
||||
GND
|
||||
|
||||
CLOCK_DELAY: A0 - you should connect a potentiometer to A0, this will let you manually sed the clock delay of the 6502.
|
||||
|
||||
Note: You may want to put a 100Uf capacitor near the 3.3v & GND lines too.
|
||||
|
||||
|
||||
## Serial client recommended settings:
|
||||
You should be able to use the standard Serial Monitor in the Arduino IDE or or Platformio (Atom) or any other basic serial client.
|
||||
|
||||
|
|
|
|||
47
src/main.cpp
47
src/main.cpp
|
|
@ -4,14 +4,16 @@
|
|||
|
||||
#define CHECK_BIT(var,pos) ((var) & (1<<(pos)))
|
||||
|
||||
// General Control settings
|
||||
const int SERIAL_SPEED = 115200; // Arduino Serial Speed
|
||||
|
||||
const int CLOCK_PIN = 52; // TO 6502 CLOCK
|
||||
const int RW_PIN = 53; // TO 6502 R/W
|
||||
const int CLOCK_DELAY = 3; // HIGH / LOW CLOCK STATE DELAY (You can slow down it as much as you want)
|
||||
const int CLOCK_DELAY_PIN = A0; // Clock delay PIN (potentiometer)
|
||||
int CLOCK_DELAY = 5; // HIGH / LOW CLOCK STATE DELAY (You can slow down it as much as you want)
|
||||
|
||||
const char SERIAL_BS = 0x08;
|
||||
|
||||
// 6502 to Arduino Pin Mapping
|
||||
const int CLOCK_PIN = 52; // TO 6502 CLOCK
|
||||
const int RW_PIN = 53; // TO 6502 R/W
|
||||
const int ADDRESS_PINS[] = {44,45,2,3,4,5,6,7,8,9,10,11,12,13,46,47}; // TO ADDRESS PIN 1-15 6502
|
||||
const int DATA_PINS[] = {33, 34, 35, 36, 37,38, 39, 40}; // TO DATA BUS PIN 0-7 6502
|
||||
|
||||
|
|
@ -49,26 +51,33 @@ const unsigned char BS = 0xDF; // Backspace key, arrow left key (B7 High)
|
|||
const unsigned char CR = 0x8D; // Carriage Return (B7 High)
|
||||
const unsigned char ESC = 0x9B; // ESC key (B7 High)
|
||||
|
||||
// 6502 States buffer
|
||||
unsigned int address; // Current address (from 6502)
|
||||
unsigned char bus_data; // Data Bus value (from 6502)
|
||||
int rw_state; // Current R/W state (from 6502)
|
||||
|
||||
unsigned int pre_address; // Current address (from 6502)
|
||||
unsigned char pre_bus_data; // Data Bus value (from 6502)
|
||||
int pre_rw_state; // Current R/W state (from 6502)
|
||||
// 6502 previous States buffer
|
||||
// We use them to optimize the performance a bit
|
||||
unsigned int pre_address; // Previous address (from 6502)
|
||||
unsigned char pre_bus_data; // Previous Bus value (from 6502)
|
||||
int pre_rw_state; // Previous R/W state (from 6502)
|
||||
|
||||
|
||||
// Set Arduino Address connected PINS as INPUT
|
||||
void setupAddressPins() {
|
||||
for (int i = 0; i < 16; ++i) {
|
||||
pinMode(ADDRESS_PINS[i], INPUT);
|
||||
}
|
||||
}
|
||||
|
||||
// Set Arduino Bus conneced pins mode as IN or OUT
|
||||
void setBusMode(int mode) {
|
||||
for (int i = 0; i < 8; ++i) {
|
||||
pinMode(DATA_PINS[i], mode);
|
||||
}
|
||||
}
|
||||
|
||||
// Read 6502 Address PINS and store the WORD in our address var
|
||||
void readAddress() {
|
||||
address = 0;
|
||||
for (int i = 0; i < 16; ++i)
|
||||
|
|
@ -78,6 +87,7 @@ void readAddress() {
|
|||
}
|
||||
}
|
||||
|
||||
// Read 6502 Data PINS and store the BYTE in our bus_data var
|
||||
void readData() {
|
||||
bus_data = 0;
|
||||
for (int i = 0; i < 8; ++i)
|
||||
|
|
@ -87,6 +97,7 @@ void readData() {
|
|||
}
|
||||
}
|
||||
|
||||
// Read RW_PIN state and set the busMode (aruduino related PINS) to OUTPUT or INPUT
|
||||
void handleRWState() {
|
||||
int tmp_rw_state=digitalRead(RW_PIN);
|
||||
|
||||
|
|
@ -255,6 +266,14 @@ void loadPROG() {
|
|||
void setup() {
|
||||
pinMode(CLOCK_PIN, OUTPUT);
|
||||
pinMode(RW_PIN, INPUT);
|
||||
pinMode(RW_PIN, INPUT);
|
||||
|
||||
// You can remove the PIN input here and just set CLOCK_DELAY as const
|
||||
// Remove also the analogRead on CLOCK_DELAY_PIN in step() below.
|
||||
pinMode(CLOCK_DELAY_PIN, INPUT);
|
||||
CLOCK_DELAY=analogRead(CLOCK_DELAY_PIN);
|
||||
// End of remove
|
||||
|
||||
|
||||
setupAddressPins();
|
||||
setBusMode(OUTPUT);
|
||||
|
|
@ -273,6 +292,8 @@ void setup() {
|
|||
Serial.print("ERAM: ");
|
||||
Serial.print(sizeof(RAM_BANK_2));
|
||||
Serial.println(" BYTE");
|
||||
Serial.print("CLOCK DELAY: ");
|
||||
Serial.println(CLOCK_DELAY);
|
||||
|
||||
loadBASIC();
|
||||
loadPROG();
|
||||
|
|
@ -294,17 +315,25 @@ void handleClock() {
|
|||
}
|
||||
|
||||
void handleBusRW() {
|
||||
// READ OR WRITE TO BUS?
|
||||
|
||||
// If nothing changed from the last cycle, we don't need to upadte anything
|
||||
if (pre_address != address || pre_rw_state != rw_state) {
|
||||
// READ OR WRITE TO BUS?
|
||||
rw_state ? writeToDataBus() : readFromDataBus();
|
||||
pre_address = address;
|
||||
pre_rw_state = rw_state;
|
||||
}
|
||||
}
|
||||
|
||||
void loop () {
|
||||
void step() {
|
||||
|
||||
CLOCK_DELAY=analogRead(CLOCK_DELAY_PIN); // Can be removed, see setup()
|
||||
handleClock();
|
||||
readAddress();
|
||||
handleBusRW();
|
||||
handleKeyboard();
|
||||
}
|
||||
|
||||
void loop () {
|
||||
step();
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue