Added support for LOAD & SAVE commands via Apple-1 Serial Interface

.gitignore

@@ -0,0 +1,2 @@
+*.bin
+*.o

Makefile

@@ -1,7 +1,7 @@
 AFLAGS  =
-LFLAGS  = -C replica1.cfg
+LFLAGS  = -C apple1cartridge.cfg
 BINFILE = applesoft-lite.bin
-OBJS    = applesoft-lite.o io.o cffa1.o wozmon.o
+OBJS    = applesoft-lite.o io.o apple1serial.o
 
 $(BINFILE): $(OBJS)
 	ld65 $(LFLAGS) $(OBJS) -o $(BINFILE)
@@ -12,7 +12,7 @@ applesoft-lite.o: applesoft-lite.s
 wozmon.o: wozmon.s
 	ca65 $(AFLAGS) $<
 
-cffa1.o: cffa1.s
+apple1serial.o: apple1serial.s
 	ca65 $(AFLAGS) $<
 
 io.o: io.s
@@ -20,4 +20,3 @@ io.o: io.s
 
 clean:
 	rm $(OBJS) $(BINFILE)
-

README.md

@@ -3,3 +3,15 @@
 This is a stripped-down version of Applesoft BASIC (Microsoft 6502 BASIC) for the Apple-1.
 
 See https://cowgod.org/replica1/applesoft/
+
+# apple1serial
+
+This branch has been modified to perform LOAD and SAVE operations via Apple-1 Serial interface
+https://github.com/flowenol/apple1serial
+
+# How to use LOAD?
+
+The LOAD command implemented on this branch takes as an argument the length of the program
+as a decimal value, e.g.,
+
+]LOAD 1024

apple1cartridge.cfg

@@ -0,0 +1,7 @@
+MEMORY {
+	BASROM:		start = $6000, size = $2000, fill = yes, file = %O;
+}
+
+SEGMENTS {
+	BASIC:		load = BASROM,	type = ro;
+}

apple1serial.s

@@ -0,0 +1,233 @@
+.setcpu "6502"
+.segment "BASIC"
+
+.include "zeropage.s"
+
+.importzp ERR_SYNTAX, ERR_NOSERIAL
+.import ERROR, FIX_LINKS, OUTDO
+.export SerialLoad, SerialSave, SerialMenu
+
+SERIAL_MONITOR := $C100
+SERIAL_READY := $C000
+SERIAL_ID := $C0FC
+SERIAL_API_READ := $C1EC
+SERIAL_API_WRITE := $C213
+
+; ZP locations get backed up here
+ZPTemp		:= $0380
+
+;End address of dump block
+END_ADDR_L := $34
+END_ADDR_H := $35
+
+;Begin address of dump block
+BEG_ADDR_L := $36
+BEG_ADDR_H := $37
+
+;String to int ZP variables
+STR2INT_BUF := $38
+STR2INT_INT := $3E
+
+STR2INT_END := $0A
+
+; ----------------------------------------------------------------------------
+; See if Apple-1 Serial Interface card is present and display error if not
+; ----------------------------------------------------------------------------
+CheckSerial:
+	ldy	SERIAL_ID
+	cpy	#'A'
+	bne	SerialErr
+	ldy	SERIAL_ID + 1
+	cpy	#'1'
+	bne	SerialErr
+	ldy	SERIAL_ID + 2
+	cpy	#'S'
+	bne	SerialErr
+	ldy	SERIAL_ID + 3
+	cpy	#'I'
+	bne	SerialErr
+	rts
+
+SerialErr:
+  ldx	#ERR_NOSERIAL
+  .byte	$2C		; Bogus BIT instruction
+SynErr:
+  ldx	#ERR_SYNTAX
+  jmp	ERROR		; Jump to Applesoft ERROR routine
+
+
+; ----------------------------------------------------------------------------
+; Bring up the Apple-1 Serial Interface menu
+; ----------------------------------------------------------------------------
+SerialMenu:
+  jsr	CheckSerial
+	jsr SERIAL_MONITOR
+
+
+; ----------------------------------------------------------------------------
+; Save program via the Apple-1 Serial Interface
+; ----------------------------------------------------------------------------
+SerialSave:
+	jsr	CheckSerial
+
+	ldy	#0
+@1:
+	lda	END_ADDR_L,y	; Back up 4 affected bytes of the ZP
+	sta	ZPTemp,y
+	iny
+	cpy	#4
+	bne	@1
+
+	lda	PRGEND		; Set up end address
+	sta END_ADDR_L
+	lda	PRGEND+1
+	sta END_ADDR_H
+	lda	TXTTAB		; Set up start address
+	sta BEG_ADDR_L
+	lda	TXTTAB+1
+	sta BEG_ADDR_H
+
+	jsr SERIAL_API_WRITE
+	jsr	RestoreZPForSave	; Put the zero page back
+  rts
+
+; ----------------------------------------------------------------------------
+; Restores the 4 bytes of the ZP which were saved during SerialSave
+; ----------------------------------------------------------------------------
+RestoreZPForSave:
+	ldy	#0
+@1:
+  lda	ZPTemp,y	; Load byte from temporary storage
+	sta	END_ADDR_L,y	; put it back in its original location
+	iny
+	cpy	#4		; Repeat for next 11 bytes
+	bne	@1
+	rts
+
+
+; ----------------------------------------------------------------------------
+; Read program from Apple-1 Serial Interface
+; ----------------------------------------------------------------------------
+SerialLoad:
+  jsr	CheckSerial
+
+	ldy	#0
+@1:
+  lda	END_ADDR_L,y	; Back up first 12 bytes of the ZP
+	sta	ZPTemp,y
+	iny
+	cpy	#12
+	bne	@1
+
+GetLength:	; Get file name from input line
+	dec	TXTPTR
+	ldy	#0
+@1:
+  jsr	CHRGET		; Get next character from the input line
+	beq	@2		    ; Is it null (EOL)?
+	cmp #$30
+	bmi LengthValidationErr
+	cmp #$3A
+	bpl LengthValidationErr
+	and #$0F      ; Convert ASCII to hex value $00-$09
+	sta	STR2INT_BUF,y	; Not EOL, store it in program length string
+	iny
+	cpy	#5			; 6 chars yet?
+	bne	@1			; no
+
+@2:
+	cpy	#0			; Read 6 chars or EOL, did we get anything?
+	beq	SynErr
+
+	lda #STR2INT_END    ; append integer string end marker
+	sta STR2INT_BUF,y
+	jsr String2Int
+	lda STR2INT_INT
+	bne @3
+	dec STR2INT_INT+1
+@3:
+	dec STR2INT_INT
+	clc
+SetLoadAddresses:
+	lda	TXTTAB		; Compute program end address
+	adc	STR2INT_INT	  ; (Add file size to program start)
+	sta	VARTAB		; Store end address
+	sta END_ADDR_L
+	lda	TXTTAB+1
+	adc	STR2INT_INT+1
+	sta	VARTAB+1
+	sta END_ADDR_H
+
+	;jsr SerialAPISetup
+	lda	TXTTAB		; Set up start address
+	sta BEG_ADDR_L
+	lda	TXTTAB+1
+	sta BEG_ADDR_H
+
+	jsr SERIAL_API_READ
+	jsr	RestoreZPForLoad	; Put the zero page back
+
+	jmp	FIX_LINKS
+LengthValidationErr:
+	jsr RestoreZPForLoad
+	jmp SynErr
+; ----------------------------------------------------------------------------
+; Restores the affected 12 bytes of the ZP which were saved during SerialLoad
+; ----------------------------------------------------------------------------
+RestoreZPForLoad:
+	ldy	#0
+@1:
+  lda	ZPTemp,y	; Load byte from temporary storage
+	sta	END_ADDR_L,y	; put it back in its original location
+	iny
+	cpy	#12		; Repeat for next 11 bytes
+	bne	@1
+	rts
+
+; ----------------------------------------------------------------------------
+; Converts the integer string to 2 byte integer
+; ----------------------------------------------------------------------------
+String2Int:
+  lda #0
+  sta STR2INT_INT+1
+  lda STR2INT_BUF
+  sta STR2INT_INT
+  ldx #1
+  lda STR2INT_BUF,X
+  cmp #STR2INT_END
+  bne String2IntNext
+  clc
+  rts
+String2IntNext:
+  jsr String2IntMult10
+  bcs String2IntEnd
+  inx
+  lda STR2INT_BUF,X
+  cmp #$0A
+  bne String2IntNext
+  clc
+String2IntEnd:
+	rts
+
+String2IntMult10:
+  lda STR2INT_INT+1
+  pha
+  lda STR2INT_INT
+  asl STR2INT_INT
+  rol STR2INT_INT+1
+  asl STR2INT_INT
+  rol STR2INT_INT+1
+  adc STR2INT_INT
+  sta STR2INT_INT
+  pla
+  adc STR2INT_INT+1
+  sta STR2INT_INT+1
+  asl STR2INT_INT
+  rol STR2INT_INT+1
+  lda STR2INT_BUF,X
+  adc STR2INT_INT
+  sta STR2INT_INT
+  lda #0
+  adc STR2INT_INT+1
+  sta STR2INT_INT+1
+  rts

applesoft-lite.s

@@ -8,20 +8,20 @@
 ; Adapted for the Replica-1 by Tom Greene
 ; 7-May-2008
 ;
-; v0.4
+; Changed to support LOAD & SAVE via Apple-1 Serial Interface by Piotr Jaczewski
-
+; 15-Jan-2021
-
+;
 
 .setcpu "6502"
 .segment "BASIC"
 
 .export FIX_LINKS, ERROR, INPUTBUFFER
-.exportzp ERR_SYNTAX, ERR_NOCFFA
+.exportzp ERR_SYNTAX, ERR_NOSERIAL
 
 .import CLS, OUTDO, CRDO, OUTSP, OUTQUES	; Imports from io.s
 .import KEYBOARD, GETLN, RDKEY
 
-.import CFFALoad, CFFASave, CFFAMenu		; Imports from cffa1.s
+.import SerialLoad, SerialSave, SerialMenu		; Imports from apple1serial.s
 
 .include "macros.s"
 .include "zeropage.s"
@@ -95,9 +95,9 @@ TOKEN_ADDRESS_TABLE:
 	.addr	CLEAR - 1	; $9B... 154... CLEAR
 	.addr	GET - 1		; $9C... 155... GET
 	.addr	NEW - 1		; $9D... 156... NEW
-	.addr	CFFAMenu - 1	; $9E... 157... MENU
+	.addr	SerialMenu - 1	; $9E... 157... MENU
-	.addr	CFFASave - 1	; $9F... 158... SAVE
+	.addr	SerialSave - 1	; $9F... 158... SAVE
-	.addr	CFFALoad - 1	; $A0... 160... LOAD
+	.addr	SerialLoad - 1	; $A0... 160... LOAD
 	.addr	CLS - 1		; $A1... 161... CLS
 ; ----------------------------------------------------------------------------
 UNFNC:  .addr	SGN		; $B1... 177... SGN
@@ -191,7 +191,7 @@ TOKEN_NAME_TABLE:
 	htasc	"NEW"		; $9D... 157
 	htasc	"MENU"		; $9E... 158   New tokens
 	htasc	"SAVE"		; $9F... 159   for
-	htasc	"LOAD"		; $A0... 160   CFFA I/O
+	htasc	"LOAD"		; $A0... 160   Apple-1 Serial I/O
 	htasc	"CLS"		; $A1... 161   New token to clear screen
 	htasc	"TO"		; $A2... 162
 	htasc	"SPC("		; $A3... 163
@@ -281,8 +281,8 @@ ERR_FRMCPX	:= <(*-ERROR_MESSAGES)
 ERR_CANTCONT	:= <(*-ERROR_MESSAGES)
 	htasc	"CAN'T CONT"
 
-ERR_NOCFFA	:= <(*-ERROR_MESSAGES)	; New error message for CFFA1 I/O
+ERR_NOSERIAL	:= <(*-ERROR_MESSAGES)	; New error message for Apple 1 Serial IO
-	htasc	"NO CFFA"
+	htasc	"NO SERIAL"
 ; ----------------------------------------------------------------------------
 QT_ERROR:
 	.byte	" ERR"
@@ -415,7 +415,7 @@ REASON:	cpy	FRETOP+1	; HIGH BYTE
 	dex
 	bpl	@2
 	jsr	GARBAG		; MAKE AS MUCH ROOM AS POSSIBLE
-	ldx	#TEMP1-FAC+1	; RESTORE TEMP1 AND TEMP2
+	ldx	#TEMP1-FAC+1+256	; RESTORE TEMP1 AND TEMP2
 @3:	pla			; AND (Y,A)
 	sta	FAC,x
 	inx
@@ -638,7 +638,7 @@ INLIN2:	stx	PROMPT
 ;	dex
 ;	bne	@2
 ;@3:	lda	#0		; (Y,X) POINTS AT BUFFER-1
-	ldx	#<INPUTBUFFER-1
+	ldx	#<INPUTBUFFER-1+256
 	ldy	#>INPUTBUFFER-1
 	rts
 
@@ -751,7 +751,7 @@ PARSE:	inx			; NEXT INPUT CHARACTER
 ; ---END OF LINE------------------
 @17:	sta	INPUTBUFFER-3,y	; STORE ANOTHER 00 ON END
 	dec	TXTPTR+1	; SET TXTPTR = INPUTBUFFER-1
-	lda	#<INPUTBUFFER-1
+	lda	#<INPUTBUFFER-1+256
 	sta	TXTPTR
 	rts
 
@@ -941,7 +941,7 @@ LIST4:	bpl	LIST2		; BRANCH IF NOT A TOKEN
 	sty	FAC		; POINT FAC TO TABLE
 	ldy	#>(TOKEN_NAME_TABLE-$100)
 	sty	FAC+1
-	ldy	#-1
+	ldy	#$FF
 @1:	dex			; SKIP KEYWORDS UNTIL REACH THIS ONE
 	beq	@3
 @2:	jsr	GETCHR		; BUMP Y, GET CHAR FROM TABLE
@@ -2961,7 +2961,7 @@ STR:	jsr	CHKNUM		; EXPRESSION MUST BE NUMERIC
 	jsr	FOUT1		; CONVERT FAC TO STRING
 	pla			; POP RETURN OFF STACK
 	pla
-	lda	#<STACK-1	; POINT TO STACK-1
+	lda	#<STACK-1+256	; POINT TO STACK-1
 	ldy	#>STACK-1	; (WHICH=0)
 	beq	STRLIT		; ...ALWAYS, CREATE DESC & MOVE STRING
 
@@ -4258,7 +4258,7 @@ FDIVT:	beq	@8		; FAC = 0, DIVIDE BY ZERO ERROR
 	jsr	ADD_EXPONENTS
 	inc	FAC
 	beq	JOV		; OVERFLOW
-	ldx	#-4		; INDEX FOR RESULT
+	ldx	#252		; INDEX FOR RESULT
 	lda	#1		; SENTINEL
 @1:	ldy	ARG+1		; SEE IF FAC CAN BE SUBTRACTED
 	cpy	FAC+1
@@ -4850,7 +4850,7 @@ FOUT1:	lda	#'-'		; IN CASE VALUE NEGATIVE
 @3:	lda	#<CON_BILLION	; MULTIPLY BY 1E9
 	ldy	#>CON_BILLION	; TO GIVE ADJUSTMENT A HEAD START
 	jsr	FMULT
-	lda	#-9		; EXPONENT ADJUSTMENT
+	lda	#247		; EXPONENT ADJUSTMENT
 @4:	sta	TMPEXP		; 0 OR -9
 ; ----------------------------------------------------------------------------
 ; ADJUST UNTIL 1E8 <= (FAC) <1E9
@@ -5272,7 +5272,7 @@ GENERIC_CHRGET:
 	sec			; TEST FOR NUMERIC RANGE IN WAY THAT
 	sbc	#'0'		; CLEARS CARRY IF CHAR IS DIGIT
 	sec			; AND LEAVES CHAR IN A-REG
-	sbc	#-'0'
+	sbc	#-'0'+256
 @2:	rts
 
 
@@ -5498,4 +5498,3 @@ RESUME:	lda	ERRLIN		; RESTORE LINE # AND TXTPTR
 	ldx	ERRSTK		; RETRIEVE STACK PNTR AS IT WAS
 	txs			; BEFORE STATEMENT SCANNED
 	jmp	NEWSTT		; DO STATEMENT AGAIN
-

cffa1.s

@@ -1,185 +0,0 @@
-; CFFA1 I/O routines for Applesoft Lite
-; by Tom Greene 
-; 8-May-2008
-
-.setcpu "6502"
-.segment "BASIC"
-
-.include "zeropage.s"
-
-.importzp ERR_SYNTAX, ERR_NOCFFA
-.import ERROR, FIX_LINKS
-.export CFFALoad, CFFASave, CFFAMenu
-
-; ----------------------------------------------------------------------------
-; CFFA1 firmware addresses
-
-;CFFA_ID1	:= $AFFC	; CFFA1 API documentation says AFFC and AFFD...
-;CFFA_ID2	:= $AFFD
-CFFA_ID1	:= $AFDC	; But the CFFA1 firmware says AFDC and AFDD...
-CFFA_ID2	:= $AFDD
-CFFA_MENU	:= $9006	; Entry point for the CFFA1 menu
-CFFA_API	:= $900C	; Entry point for the CFFA1 API
-
-; ----------------------------------------------------------------------------
-; CFFA1 API functions
-
-CFFA1_DisplayError	= $04	; Displays error message for error value in A
-CFFA1_WriteFile		= $20
-CFFA1_ReadFile		= $22
-
-; ----------------------------------------------------------------------------
-; CFFA1 API parameters in the ZP
-
-Destination	:= $00			; File load/save address
-Filename	:= $02			; Pointer to file name
-Filetype	:= $06			; ProDOS file type
-AuxType		:= $07			; ProDOS file auxtype
-FileSize	:= $09			; File size 
-
-; ----------------------------------------------------------------------------
-; Scratch memory used during API calls
-
-ZPTemp		:= $0380		; ZP locations get backed up here
-CFFAFileName	:= $03C0		; File name string
-
-; ----------------------------------------------------------------------------
-; ProDOS file type value for write operations
-; The CFFA1 doesn't really care, so this is just for show.
-
-SaveType	= $F8			; F8 = "PRG"?
-
-; ----------------------------------------------------------------------------
-
-
-; ----------------------------------------------------------------------------
-; See if CFFA1 card is present and display error if not
-; ----------------------------------------------------------------------------
-CheckCFFA:
-	ldy	CFFA_ID1
-	cpy	#$CF		
-	bne	CFFAErr
-	ldy	CFFA_ID2
-	cpy	#$FA
-	bne	CFFAErr
-	rts
-
-
-; ----------------------------------------------------------------------------
-; Bring up the CFFA1 menu 
-; ----------------------------------------------------------------------------
-CFFAMenu:
-	jsr	CheckCFFA
-	jmp	CFFA_MENU
-
-
-; ----------------------------------------------------------------------------
-; This sets up the zero page locations file name for the read/write calls
-; ----------------------------------------------------------------------------
-APISetup:
-	jsr	CheckCFFA	; Make sure CFFA card is present first
-	ldy	#0
-@1:	lda	GOWARM,y	; Back up first 12 bytes of the ZP
-	sta	ZPTemp,y	; so they can used during CFFA API call
-	iny
-	cpy	#12
-	bne	@1
-GetFileName:			; Get file name from input line
-	dec	TXTPTR
-	ldy	#0
-@1:	jsr	CHRGET		; Get next character from the input line
-	beq	@2		; Is it null (EOL)?
-	sta	CFFAFileName+1,y	; Not EOL, store it in filename string
-	iny
-	cpy	#15			; 15 chars yet?
-	bne	@1			; no, go back for more
-@2:	cpy	#0			; Read 15 chars or EOL, did we get anything?
-	beq	SynErr			; No, syntax error
-	sty	CFFAFileName		; Store file name length
-	lda	#<CFFAFileName		; Load address of file name string
-	ldy	#>CFFAFileName
-	sta	Filename		; and store it for API call
-	sty	Filename+1
-	lda	PRGEND		; Set up file size
-	sbc	TXTTAB		; (PRGEND - TXTTAB)
-	sta	FileSize
-	lda	PRGEND+1
-	sbc	TXTTAB+1
-	sta	FileSize+1
-	lda	TXTTAB		; Set up start address and auxtype
-	ldy	TXTTAB+1	; (these will be the same)
-	sta	Destination
-	sta	AuxType
-	sty	Destination+1
-	sty	AuxType+1
-	lda	#SaveType	; Set up ProDOS file type
-	sta	Filetype
-	rts
-
-
-; ----------------------------------------------------------------------------
-; Display an error message if something went wrong during APISetup
-; Uses the Applesoft ERROR routine
-; ----------------------------------------------------------------------------
-CFFAErr:
-	ldx	#ERR_NOCFFA
-	.byte	$2C		; Bogus BIT instruction
-SynErr:
-	ldx	#ERR_SYNTAX
-	jmp	ERROR		; Jump to Applesoft ERROR routine
-
-
-; ----------------------------------------------------------------------------
-; Restores the first 12 bytes of the ZP which were saved during APISetup
-; ----------------------------------------------------------------------------
-RestoreZP:
-	ldy	#0
-@1:	lda	ZPTemp,y	; Load byte from temporary storage
-	sta	GOWARM,y	; put it back in its original location
-	iny
-	cpy	#12		; Repeat for next 11 bytes	
-	bne	@1
-	rts
-
-
-; ----------------------------------------------------------------------------
-; Write a file to the CFFA card (SAVE command)
-; ----------------------------------------------------------------------------
-CFFASave:
-	jsr	APISetup	; Set up zero page locations for API call
-	ldx	#CFFA1_WriteFile; Select WriteFile API function
-	jsr	DoCFFACall	; Do it
-@1:	jsr	RestoreZP	; put ZP back together
-@2:	rts
-
-
-; ----------------------------------------------------------------------------
-; Read file from CFFA, then fix up Applesoft zero page to point to the 
-; loaded program (LOAD command)
-; ----------------------------------------------------------------------------
-CFFALoad:
-	jsr	APISetup
-	ldx	#CFFA1_ReadFile	; Select ReadFile API function
-	jsr	DoCFFACall	; Do it
-	lda	TXTTAB		; Compute program end address
-	adc	FileSize	; (Add file size to program start)
-	sta	VARTAB		; Store end address
-	lda	TXTTAB+1	
-	adc	FileSize+1
-	sta	VARTAB+1
-	jsr	RestoreZP	; Put the zero page back
-	jmp	FIX_LINKS	; Done loading, fix pointers and restart
-
-
-; ----------------------------------------------------------------------------
-; Call the CFFA1 API and display error message if one occurred
-; CFFA function number is passed in X
-; CFFA API returns error status in C, error number in A
-; ----------------------------------------------------------------------------
-DoCFFACall:			
-	jsr	CFFA_API		; Call CFFA API
-	ldx	#CFFA1_DisplayError	; Set next command to show error message
-	bcs	DoCFFACall		; Call API again if error occurred
-	rts
-
-

replica1.cfg

@@ -1,10 +0,0 @@
-MEMORY {
-	BASROM:		start = $E000, size = $1F00, fill = yes, file = %O;
-	MONROM:		start = $FF00, size = $100, fill = yes, file = %O;
-}
-
-SEGMENTS {
-	BASIC:		load = BASROM,	type = ro;
-	MONITOR:	load = MONROM,	type = ro;
-}
-

wozmon.s

@@ -1,183 +0,0 @@
-; Apple I Monitor ROM
-; Steve Wozniak
-; 1976
-; --------------------------------------------------------
-
-.setcpu	"6502"
-.segment "MONITOR"
-
-.export ECHO
-
-; --------------------------------------------------------
-; Zero page variables
-XAML	:= $24
-XAMH	:= $25
-STL	:= $26
-STH	:= $27
-L	:= $28
-H	:= $29
-YSAV	:= $2A
-MODE	:= $2B
-
-; I/O locations
-IN	:= $0200		; Input buffer is $0200 to $027F
-KBD	:= $D010		; Keyboard data
-DSP	:= $D012		; Display data
-KBDCR	:= $D011		; Keyboard control register
-DSPCR	:= $D013		; Display control register
-
-; ASCII codes
-CR	= $0D | $80		; Carriage return
-ESC	= $1B | $80		; Escape
-SLASH	= '\' | $80		; \
-UNDERSC = '_' | $80		; Underscore (acts as backspace)
-DOT	= '.' | $80		; .
-COLON	= ':' | $80		; :
-R	= 'R' | $80		; "R"
-SPACE	= ' ' | $80		; blank
-ZERO	= '0' | $80		; "0"
-
-; --------------------------------------------------------
-RESET:	cld			; Clear decimal arithmetic mode
-	cli
-	ldy	#$7F		; Mask for DSP data direction register
-	sty	DSP		; Set it up
-	lda	#$A7		; KBD and DSP control register mask
-	sta	KBDCR		; Enable interrupts, set CA1, CB1 for
-	sta	DSPCR		;   positive edge sense/output mode
-NOTCR:	cmp	#UNDERSC	; Backspace?
-	beq	BACKSPACE	; Yes
-	cmp	#ESC		; ESC?
-	beq	ESCAPE		; Yes
-	iny			; Advance text index
-	bpl	NEXTCHAR	; Auto ESC if > 127
-ESCAPE:	lda	#SLASH		; "\"
-	jsr	ECHO		; Output it
-GETLINE:
-	lda	#CR		; CR
-	jsr	ECHO		; Output it
-	ldy	#$01		; Initialize text index
-BACKSPACE:
-	dey			; Back up text index
-	bmi	GETLINE		; Beyond start of line, reinitialize
-NEXTCHAR:
-	lda	KBDCR		; Key ready?
-	bpl	NEXTCHAR	; Loop until ready
-	lda	KBD		; Load character. B7 should be '1'
-	sta	IN,y		; Add to text buffer
-	jsr	ECHO		; Display character
-	cmp	#CR		; CR?
-	bne	NOTCR		; No
-	ldy	#$FF		; Reset text index
-	lda	#$00		; For XAM mode
-	tax			; 0 -> x
-SETSTOR:
-	asl			; Leaves $7B if setting STOR mode
-SETMODE:
-	sta	MODE		; $00 = XAM, $7B = STOR, $AE = BLOCK XAM
-BLSKIP:	iny			; Advance text index
-NEXTITEM:
-	lda	IN,y		; Get character
-	cmp	#CR		; CR?
-	beq	GETLINE		; Yes, done this line
-	cmp	#DOT		; "."?
-	bcc	BLSKIP		; Skip delimiter
-	beq	SETMODE		; Set BLOCK XAM mode
-	cmp	#COLON		; ":"?
-	beq	SETSTOR		; Yes, set STOR mode
-	cmp	#R		; "R"?
-	beq	RUN		; Yes, run user program
-	stx	L		; $00 -> L
-	stx	H		;   and H
-	sty	YSAV		; Save Y for comparison
-NEXTHEX:
-	lda	IN,y		; Get character for hex test
-	eor	#$B0		; Map digits to $0-9
-	cmp	#$0A		; Digit?
-	bcc	DIG		; Yes
-	adc	#$88		; Map letter "A"-"F" to $FA-FF
-	cmp	#$FA		; Hex letter?
-	bcc	NOTHEX		; No, character not hext
-DIG:	asl
-	asl			; Hex digit to MSD of A
-	asl
-	asl
-	ldx	#$04		; Shift count
-HEXSHIFT:
-	asl			; Hex digit left, MSB to carry
-	rol	L		; Rotate into LSD
-	rol	H		; Rotate into MSD's
-	dex			; Done 4 shifts?
-	bne	HEXSHIFT	; No, loop
-	iny			; Advance text index
-	bne	NEXTHEX		; Always taken. Check next character for hex
-NOTHEX:
-	cpy	YSAV		; Check if L, H empty (no hex digits)
-	beq	ESCAPE		; Yes, generate ESC sequence
-	bit	MODE		; Test MODE byte
-	bvc	NOTSTOR		; B6 = 0 for STOR, 1 for XAM and BLOCK XAM
-	lda	L		; LSD's of hex data
-	sta	(STL,x)		; Store at current 'store index'
-	inc	STL		; Increment store index
-	bne	NEXTITEM	; Get next item (no carry)
-	inc	STH		; Add carry to 'store index' high order
-TONEXTITEM:
-	jmp	NEXTITEM	; Get next command item
-RUN:	jmp	(XAML)		; Run at current XAM index
-NOTSTOR:
-	bmi	XAMNEXT		; B7=0 for XAM, 1 for BLOCK XAM
-	ldx	#$02		; Byte count
-SETADR:	lda	L-1,x		; Copy hex data to
-	sta	STL-1,x		;   'store index'
-	sta	XAML-1,x	; And to 'XAM index'
-	dex			; Next of 2 bytes
-	bne	SETADR		; Loop unless X=0
-NXTPRNT:
-	bne	PRDATA		; NE means no address to print
-	lda	#CR		; CR
-	jsr	ECHO		; Output it
-	lda	XAMH		; 'Examine index' high-order byte
-	jsr	PRBYTE		; Output it in hex format
-	lda	XAML		; Low-order 'examine index' byte
-	jsr	PRBYTE		; Output it in hex format
-	lda	#COLON		; ":"
-	jsr	ECHO		; Output it
-PRDATA:	lda	#SPACE		; Blank
-	jsr	ECHO		; Output it
-	lda	(XAML,x)	; Get data byte at 'examine index'
-	jsr	PRBYTE		; Output it in hex format
-XAMNEXT:
-	stx	MODE		; 0 -> MODE (XAM mode)
-	lda	XAML
-	cmp	L		; Compare 'examine index' to hex data
-	lda	XAMH
-	sbc	H
-	bcs	TONEXTITEM	; Not less, so no more data to output
-	inc	XAML
-	bne	MOD8CHK		; Increment 'examine index'
-	inc	XAMH
-MOD8CHK:
-	lda	XAML		; Check low-order 'examine index' byte
-	and	#$07		;   For MOD 8 = 0
-	bpl	NXTPRNT		; Always taken
-PRBYTE:	pha			; Save A for LSD
-	lsr
-	lsr
-	lsr			; MSD to LSD position
-	lsr
-	jsr	PRHEX		; Output hex digit
-	pla			; Restore A
-PRHEX:	and	#$0F		; Mask LSD for hex print
-	ora	#ZERO		; Add "0"
-	cmp	#$BA		; Digit?
-	bcc	ECHO		; Yes, output it
-	adc	#$06		; Add offset for letter
-ECHO:	bit	DSP		; DA bit (B7) cleared yet?
-	bmi	ECHO		; No, wait for display
-	sta	DSP		; Output character. Sets DA.
-	rts			; Return
-; --------------------------------------------------------
-	.word	$0000		; (unused)
-	.addr	$0F00		; (NMI vector)
-	.addr	RESET		; (RESET vector)
-	.addr	$0000		; (IRQ vector)