; Level 1 Basic for the TRS-80 Model 1 and Model 3.
;
; Uncomment one of these to choose the version.
;
;model  equ     1
;model  equ     3
;
; What's different between the Model 1 and Model 3 versions?
;
; Not very much.  They're quite similar at the source code level and the Model 3
; version is obviously meant to be compatible.  The Model 3 version has two
; new features:
;
;       Runs on Model 3 hardware
;       Line printer support via LPRINT and LLIST
;
; Due to LLIST the model 3 LIST command is different.  It lists lines continuously
; rather than listing 12 and waiting for the up-arrow key for each line
; thereafter or the enter key to quit.
;
; The Model 3 version allows anything after a GOTO's line number.  Perhaps that
; was to save 3 bytes in the ROM by eliminating a call.  This program will work
; on the Model 3 but not the Model 1:
;
;       10 GOTO20A
;       20 END
;
; Otherwise the implementation of BASIC is identical.
;
; At a binary level the ROMs look quite different but that's because the Model 3
; version was rebuilt from source.  A small number of changes account for I/O
; hardware differences.  Mostly things were rearranged to use a few wasted bytes.
; The cassette routines manage to save the most through slightly tighter coding.
; Another saving comes from the Model 3 NEW resetting the machine rather than
; reinitialize the BASIC program.
;
; The cassette bit rate is practically the same.  Counting cycles in putbit
; I found the ratios a bit off.  The entire routine is 3380 cycles on the Model 1
; and 4017 cycles on the Model 3 with pulse spaces of 222 and 251 cycles respectively.
; The putbit routine takes 1.188 times more cycles while the pulse spacing cycle
; ratio is 1.13.  Both are a little off the Z-80 clock ratio of about 1.17 for
; the Model 3's 2.0752 MHz over the Model 1's 1.77408 MHz.  Nevertheless, I
; have no doubt they're interoperable.
;
; With the surprising exception of the BASIC READY prompt the Level 1 ROM
; subroutine addresses from the T-BUG manual are the same.  I suspect part of
; the code re-arrangement was intended to preserve these.
;
;       $0010   display byte
;       $0B40   keyboard scan
;       $0EF4   load memory from cassette
;       $0F4B   save memory to cassette
;       $0FE9   cassette on
;       $01C9   BASIC READY prompt (Model 1)
;       $01B7   BASIC READY prompt (Model 3)
;
; In what may be no coincidence, $01C9 is the READY entry point for Model 1
; Level II BASIC and Model 3 Level II BASIC.  $01C9 will sort of work on
; Model 3 Level 1 but will not display the prompt and won't quite be
; properly initialized.
;
; The RST vector subroutines are re-arranged slightly.
;
; Most of the disassembly here was automatically generated.  By and large I've
; only annotated things in order to sort out the differences between the two
; ROMs.  More than a few of the labels are guesses -- beware!
;
drow	macro	n
	defb	[n]/256
	defb	[n]&255
	endm
	org	00000h
sub00:	di
	ld	hl,0ffh
	if	model == 1
	jp	findtop
	nop
	endif
	if	model == 3
findtop:	dec	h
	ld	a,(hl)
	jr	cont_findtop
	endif
; Searches for byte following rst.  If found returns to ret addr + 2.
; If not found, then adds 2nd byte after rst to address of that byte + 1
; and returns there.  Think of it as 'if not char then label'
lkchar:	ex	(sp),hl
	rst	skipspace
	cp	(hl)
	jp	cont_lkchar
put_lf:	ld	a,00dh
; I don't use the official name as this outputs to multiple devices.
putch:
	if	model == 1
	exx
	ex	af,af'
	call	gtstat
	endif
	if	model == 3
	ex	af,af'
	in	a,(0ffh)
	and	002h
	endif
	jp	cont_putch
def_skipspace	macro
skipspace:	ld	a,(de)
	cp	020h
	ret	nz
	inc	de
	jp	skipspace
	endm
	if	model == 1
expr:	call	sub68
	nop
	jp	cont_expr
	nop
call_expr	macro
	rst	expr
	endm
	endif
	if	model == 3
	def_skipspace
call_expr	macro
	call	expr
	endm
	endif
cpHL_DE:	ld	a,h
	cp	d
	ret	nz
	ld	a,l
	cp	e
	ret
	if	model == 1
	nop
	nop
	def_skipspace
	endif
	if	model == 3
; Like put_lf, but does a bit more.
put_lf2:	ld	a,00dh
; Sets output device to video.
vidputc:	push	af
	xor	a
	ld	(outdev),a
	pop	af
	jr	putch
	endif
sub07:	pop	af
	call	sub84
	jp	say_what_de
	nop
; Parse variable reference (either A,B,...Z or A(n)).  Returns address of
; variable in HL if and carry clear if successful.  Carry set if error.
lkvar:	rst	skipspace
	sub	041h
	ret	c
	cp	01ah
	ccf
	ret	c
	inc	de
	and	a
	jr	nz,getvarA
	rst	lkchar
	defb	'(',getvars-$-1
	call	sub75
	inc	hl
	add	hl,hl
	add	hl,hl
	jp	c,say_how_de
	push	hl
	rst	lkchar
	defb	')',say_what_de2-$-1
lkvar_chunk	macro
	pop	hl
	push	de
	push	hl
	ld	hl,(memtop)
	ld	de,(freemem)
	xor	a
	sbc	hl,de
	pop	de
	rst	cpHL_DE
	endm
	if	model == 1
	lkvar_chunk
	jp	cont_lkvar
	endif
	if	model == 3
	jr	cont_lkvar
cont_findtop:	cpl
	ld	(hl),a
	cp	(hl)
	cpl
	ld	(hl),a
	jr	nz,findtop
	ld	(memtop),hl
	ld	hl,basic_mem
	ld	(freemem),hl
	endif
; NMI entry point as triggered by reset button at back of keyboard.
nmi:	di
	ld	sp,basic_mem
	xor	a
	if	model == 1
	ld	(status),a
	out	(0ffh),a
	ld	a,00ch
	rst	putch
	endif
	if	model == 3
	out	(0e0h),a
	out	(0ffh),a
	out	(0e4h),a
	ld	a,020h
	out	(0ech),a
	ld	a,00ch
	rst	vidputc
	endif
	jp	ready
cont_lkvar:
	if	model == 3
	lkvar_chunk
	endif
	jp	c,say_sorry
	ld	hl,(memtop)
	sbc	hl,de
	pop	de
	xor	a
	ret
getvars:	xor	a
getvarA:	ld	h,040h
	rla
	rla
	ld	l,a
	xor	a
	ret
say_what_de2:	jp	say_what_de
; Parse 0-9 and returns value in A and carry clear.  Carry set if not a digit.
getdig:	ld	a,(de)
	cp	030h
	ret	c
	cp	03ah
	ccf
	ret	c
	inc	de
	and	00fh
	ret
cont_lkchar:	inc	hl
	jr	z,_2getdig
	push	bc
	ld	c,(hl)
	ld	b,000h
	add	hl,bc
	pop	bc
	dec	de
_2getdig:	inc	de
	inc	hl
	ex	(sp),hl
	ret
sub10:	call	clr24b
	ld	b,000h
	ld	c,b
	rst	skipspace
_1sub10:	call	sub11
	jr	_1sub10
sub11:	call	getdig
	jr	c,_2sub12
	set	6,b
	bit	7,b
	jr	nz,_1sub12
	call	sub12
	bit	0,b
	ret	z
	dec	c
	ret
sub12:	call	shiftdig
	ret	z
	exx
	ld	h,d
	ld	l,e
	ex	af,af'
	ld	c,a
	exx
	set	7,b
	pop	af
_1sub12:	bit	0,b
	ret	nz
	inc	c
	ret
_2sub12:	rst	lkchar
	defb	'.',_3sub12-$-1
	bit	0,b
	set	0,b
	ret	z
_3sub12:	pop	af
	bit	6,b
	ret	z
	ld	l,018h
	ld	h,000h
	push	bc
	push	de
	exx
	call	normCHL
	ld	bc,10
	add	ix,bc
	pop	de
	ld	bc,_4sub12
	push	bc
	push	de
	jp	_3sub128
_4sub12:	pop	bc
	push	de
	rst	lkchar
	defb	'E',_8sub12-$-1
	rst	lkchar
	defb	'+',_5sub12-$-1
	jr	_6sub12
_5sub12:	rst	lkchar
	defb	'-',_6sub12-$-1
	set	1,b
_6sub12:	call	clear24
_7sub12:	call	getdig
	jr	c,_9sub12
	set	5,b
	call	shiftdig
	jp	nz,say_how_de
	jr	_7sub12
_8sub12:	pop	de
	xor	a
	jr	_10sub12
_9sub12:	bit	5,b
	jr	z,_8sub12
	pop	af
	exx
	ld	a,c
	or	h
	jr	nz,_15sub12
	ld	a,l
	exx
	bit	7,a
	jp	nz,say_how_de
	bit	1,b
	jr	z,_10sub12
	neg
_10sub12:	add	a,c
_11sub12:	and	a
	jr	z,_14sub12
	bit	7,a
	jr	z,_12sub12
	inc	a
	push	af
	call	sub122
	jr	_13sub12
_12sub12:	dec	a
	push	af
	call	sub120
_13sub12:	pop	af
	jr	_11sub12
_14sub12:	bit	6,b
	ret
_15sub12:	exx
	jp	say_how_de
; Clear the 24 bit C'H'L' register.  And clear bit 6 of B for some reason.
clr24b:	res	6,b
; Clear the 24 bit C'H'L' register.
clear24:	exx
	ld	l,000h
	ld	h,l
	ld	c,l
	exx
	ret
; Multiply 24 bit C'H'L' register by 10 and add A with overflow into B'
; That is, a 32 bit result in B'C'H'L'
shiftdig:	ex	af,af'
	exx
	ld	d,h
	ld	e,l
	ld	a,c
	ld	b,000h
	push	af
	add	hl,hl
	rl	c
	rl	b
	add	hl,hl
	rl	c
	rl	b
	add	hl,de
	adc	a,c
	ld	c,a
	ld	a,000h
	adc	a,b
	ld	b,a
	pop	af
	add	hl,hl
	rl	c
	rl	b
	ex	af,af'
	add	a,l
	ld	l,a
	ld	a,000h
	adc	a,h
	ld	h,a
	ld	a,000h
	adc	a,c
	ld	c,a
	ld	a,000h
	adc	a,b
	ld	b,a
	exx
	ret
	if	model == 1
; Figure out how much memory we have.
findtop:	dec	h
	ld	a,(hl)
	cpl
	ld	(hl),a
	xor	(hl)
	jr	nz,findtop
	ld	(memtop),hl
	xor	a
	ld	(status),a
	ld	sp,basic_mem
	jp	_1NEW_
	endif
say_how_de:	push	de
say_how:	ld	de,msg_HOW
	jp	errmsg
msg_HOW:	ascii	'HOW?',13
rws_msg	macro
msg_READY:	ascii	'READY',13
msg_WHAT:	ascii	'WHAT?',13
msg_SORRY:	ascii	'SORRY',13
	endm
	if	model == 1
	rws_msg
	endif
msg_BREAK_AT:	ascii	'BREAK AT',0
ready:	ld	sp,basic_mem
	call	ctoff
	if	model == 1
	call	put_lf
	endif
	if	model == 3
	call	put_lf2
	endif
	ld	de,msg_READY
	call	print
; Like ready but doesn't show the full 'READY\n>' prompt.  Just '>'.
getcmd:	ld	sp,basic_mem
	call	clear
; Ready but with short prompt and no clearing of basic run state.
cmdlive:	ld	ix,input_buffer+72
	call	getline
	push	de
	ld	de,input_buffer
	call	getint
	ld	a,h
	or	l
	pop	bc
	jp	z,exec
	dec	de
	ld	a,h
	ld	(de),a
	dec	de
	ld	a,l
	ld	(de),a
	push	bc
	push	de
	ld	a,c
	sub	e
	push	af
	call	findline
	push	de
	jr	nz,insert_line
; Line found; delete old line.
	push	de
	call	skipfindHL
	pop	bc
	ld	hl,(freemem)
	call	copyDEtoBC
	ld	h,b
	ld	l,c
	ld	(freemem),hl
; Now put in new line unless it was just an empty line number in which
; case we just let the line be deleted and/or do nothing.
insert_line:	pop	bc
	ld	hl,(freemem)
	pop	af
	push	hl
	cp	003h
	jr	z,getcmd
	add	a,l
	ld	l,a
	ld	a,000h
	adc	a,h
	ld	h,a
	ld	de,(memtop)
	rst	cpHL_DE
	jp	nc,say_sorry_de
	ld	(freemem),hl
	pop	de
	call	copyDEtoHL
	pop	de
	pop	hl
	call	copyDEtoBC
	jr	getcmd
; Clear current execution position, continue position, gosub and for stacks.
clear:	ld	b,00ah
	push	hl
	ld	hl,cont_ptr
_1clear:	ld	(hl),000h
	inc	hl
	djnz	_1clear
	ld	de,basic_mem
	pop	hl
all_tok:	ret
	ascii	'LIST'
	drow	LIST_|8000h
	if	model == 3
	ascii	'LLIST'
	drow	LLIST_|8000h
	endif
	ascii	'RUN'
	drow	RUN_|8000h
	ascii	'NEW'
	drow	NEW_|8000h
	ascii	'CONT'
	drow	CONT_|8000h
	ascii	'CLOAD'
	drow	CLOAD_|8000h
	ascii	'CSAVE'
prog_tok:	drow	CSAVE_|8000h
	ascii	'NEXT'
	drow	NEXT_|8000h
	ascii	'LET'
	drow	LET_|8000h
	ascii	'INPUT'
	drow	INPUT_|8000h
	ascii	'IF'
	drow	IF_|8000h
	ascii	'ON'
	drow	ON_|8000h
	ascii	'GOTO'
	drow	GOTO_|8000h
	ascii	'GOSUB'
	drow	GOSUB_|8000h
	ascii	'RESET'
	drow	RESET_|8000h
	ascii	'RETURN'
	drow	RETURN_|8000h
	ascii	'READ'
	drow	READ_|8000h
	ascii	'RESTORE'
	drow	RESTORE_|8000h
	ascii	'REM'
	drow	REM_|8000h
	ascii	'DATA'
	drow	REM_|8000h
	ascii	'FOR'
	drow	FOR_|8000h
	ascii	'PRINT'
	drow	PRINT_|8000h
	ascii	'SET'
	drow	SET_|8000h
	ascii	'STOP'
	drow	STOP_|8000h
	ascii	'END'
	drow	END_|8000h
	ascii	'CLS'
	drow	CLS_|8000h
	if	model == 3
	ascii	'LPRINT'
	drow	LPRINT_|8000h
	endif
ong_tok:	drow	assign|8000h
	ascii	'GOTO'
	drow	on_goto|8000h
	ascii	'GOSUB'
	drow	on_gosub|8000h
func_tok:	drow	say_what_de|8000h
	ascii	'RND'
	drow	RND_|8000h
	ascii	'ABS'
	drow	ABS_|8000h
	ascii	'MEM'
	drow	MEM_|8000h
	ascii	'INT'
	drow	INT_|8000h
	ascii	'POINT'
	drow	POINT_|8000h
to_tok:	drow	expterm|8000h
	ascii	'TO'
	drow	TO_|8000h
step_tok:	drow	say_what_de|8000h
	ascii	'STEP'
	drow	STEP_|8000h
	drow	for_top|8000h
def_print_tok	macro
print_tok:	ascii	'TAB'
	drow	TAB_|8000h
	ascii	'AT'
	drow	AT_|8000h
	ascii	'A$'
	drow	Astr|8000h
	ascii	'B$'
	drow	Bstr|8000h
	drow	print_lit|8000h
	endm
	if	model == 1
	def_print_tok
	endif
op_tok	equ	$-2
	ascii	'>'
	drow	gt_|8000h
	ascii	'='
	drow	eq_|8000h
	ascii	'<'
	drow	lt_|8000h
then_tok:	drow	prog_sn|8000h
	ascii	'THEN'
	drow	THEN_|8000h
	drow	statement2|8000h
; Runs basic commands pointed to by DE.  Terminated by CR, I suspect.
; Can be handed either the input buffer or basic program.
; Checks DE to see if it matches a token in the table at HL+1.
; The table has an ascii string followed by a high-bit set big-endian word.
; Looks for match with dot allowing abbreviations.
; The clever bit is ending the table with an empty string by having
; two addresses in a row.  Thus when you see that second address
; you know that will be taken.
exec:	ld	hl,all_tok
_1exec:	rst	skipspace
	push	de
	ld	a,(de)
	inc	de
	inc	hl
	cp	(hl)
	jr	z,_2exec
	bit	7,(hl)
	jr	nz,tokmatches
	jr	skiptok
_2exec:	ld	a,(de)
	inc	de
	inc	hl
	cp	(hl)
	jr	z,_2exec
	bit	7,(hl)
	jr	z,_4exec
tokmatches:	dec	de
	jr	runtok
_4exec:	cp	02eh
	jr	z,_6exec
skiptok:	inc	hl
	bit	7,(hl)
	jr	z,skiptok
	inc	hl
	pop	de
	jr	_1exec
_6exec:	inc	hl
	bit	7,(hl)
	jr	z,_6exec
runtok:	ld	a,(hl)
	inc	hl
	ld	l,(hl)
	and	07fh
	ld	h,a
	pop	af
	jp	(hl)
NEW_:	call	checkEOL
	if	model == 1
_1NEW_:	ld	a,00ch
	rst	putch
	ld	hl,basic_mem
	ld	(freemem),hl
ready4:	jp	ready
	endif
	if	model == 3
	rst	sub00
	endif
; Odd that we don't allow anything after the END.  Guess there's little
; point when you don't have ELSE.
END_:	call	checkEOL
	if	model == 1
	jr	ready4
	endif
	if	model == 3
ready4:	jp	ready
	endif
RUN_:	call	getintEOL
	call	clear
	jr	_2RUN_
_1RUN_:	ld	hl,0
_2RUN_:	call	findlineDE
	jr	c,ready4
_3RUN_:	ld	(cur_line),de
	inc	de
	inc	de
statement:	call	kbscan
	cp	003h
	jr	z,STOP_
	call	ctoff
	ld	ix,input_buffer+72
	ld	hl,prog_tok+1
	jr	_1exec
GOTO_:	call	sub141
	push	de
	if	model == 1
	call	checkEOL
	endif
_1GOTO_:	call	findline
	jp	nz,say_how
	pop	af
	jr	_3RUN_
STOP_:	ld	(cont_ptr),de
	if	model == 1
	ld	a,00dh
	rst	putch
	endif
	if	model == 3
	call	put_lf2
	endif
	ld	de,msg_BREAK_AT
	call	print
	ld	hl,(cur_line)
	ld	(cont_line),hl
	ld	e,(hl)
	inc	hl
	ld	d,(hl)
	ld	hl,0
	ld	(cur_line),hl
	ex	de,hl
	call	sub101
	ld	a,00dh
	rst	putch
_1STOP_:	jp	cmdlive
CONT_:	call	checkEOL
	ld	hl,(cont_ptr)
	ld	a,h
	or	l
	jr	z,ready4
	ex	de,hl
	ld	hl,(cont_line)
	ld	(cur_line),hl
	call	sub84
_1CONT_:	jr	statement
	if	model == 3
LLIST_:	ld	a,001h
	ld	(outdev),a
	endif
; The LIST keyword handler.
LIST_:	call	getintEOL
	call	findline
	if	model == 1
; List 12 lines and wait for either up-arrow to list the next line
; or ENTER to stop listing.
	ld	c,00ch
_1LIST_:	jr	c,_4LIST_
	dec	c
	jr	z,_2LIST_
	push	bc
	call	sub104
	pop	bc
	call	findlineDE
	jr	_1LIST_
_2LIST_:	call	sub104
	call	findlineDE
	jr	c,_4LIST_
_3LIST_:	call	kbscan
	jr	z,_3LIST_
	cp	01bh
	jr	z,_2LIST_
	cp	00dh
	jr	nz,_3LIST_
_4LIST_:	jr	_1STOP_
	endif
	if	model == 3
	jr	c,_4LIST_
_1LIST_:	call	sub104
	call	kbscan
	jr	z,_3LIST_
	cp	003h
	jr	z,_4LIST_
_2LIST_:	call	kbscan
	jr	z,_2LIST_
	cp	003h
	jr	z,_4LIST_
_3LIST_:	call	findlineDE
	jr	nc,_1LIST_
_4LIST_:	jr	_1STOP_
	endif
	if	model == 3
LPRINT_:	ld	a,001h
	jr	print_curdev
	endif
; The PRINT keyword handler.
PRINT_:
	if	model == 3
	xor	a
print_curdev:	ld	(outdev),a
	endif
	rst	lkchar
	defb	'#',pnotdev-$-1
	ld	hl,input_buffer
	ld	(pnum_ptr),hl
	call	cton
pnotdev:	rst	lkchar
	defb	':',pnotcln-$-1
	call	put_lf
	jr	_1CONT_
pnotcln:	rst	lkchar
	defb	00dh,pnoteol-$-1
	call	put_lf
	jp	_1RUN_
pnoteol:	ld	hl,print_tok-1
	jp	_1exec
print_lit:	call	strlit
	jr	_5AT_
	jr	_2Bstr
Astr:	ld	hl,stringA
	jr	_1Bstr
Bstr:	ld	hl,stringB
_1Bstr:	call	sub35
_2Bstr:	rst	lkchar
	defb	',',_2AT_-$-1
_3Bstr:	ld	a,(cursor)
	and	00fh
	jr	z,_3AT_
	ld	a,020h
	rst	putch
	jr	_3Bstr
AT_:	call	sub73
	ld	bc,(cursor)
	ld	a,020h
	ld	(bc),a
	ld	a,h
	or	0fch
	and	03fh
	ld	h,a
	ld	(hl),05fh
	ld	(cursor),hl
_1AT_:	rst	lkchar
	defb	',',_2AT_-$-1
	jr	_3AT_
_2AT_:	rst	lkchar
	defb	';',_4AT_-$-1
_3AT_:	call	sub84
	jr	pnoteol
_4AT_:	call	put_lf
	rst	sub07
_5AT_:	call_expr
	call	sub102
	jr	_2Bstr
TAB_:	call	sub76
	ld	a,l
	and	03fh
	ld	l,a
_1TAB_:	ld	a,(cursor)
	and	03fh
	cp	l
	jr	z,_1AT_
	jr	nc,_1AT_
	ld	a,020h
	rst	putch
	jr	_1TAB_
CLS_:	ld	a,00ch
	rst	putch
	rst	sub07
sub35:	ld	a,(hl)
	inc	hl
	and	a
	ret	z
	rst	putch
	ld	a,l
	and	00fh
	ret	z
	jr	sub35
GOSUB_:	call	sub108
	call	sub141
_1GOSUB_:	push	de
	call	findline
	jp	nz,say_how
	ld	hl,(cur_line)
	push	hl
	ld	hl,(gosub_sp)
	push	hl
	ld	hl,0
	ld	(for_sp),hl
	add	hl,sp
	ld	(gosub_sp),hl
	jp	_3RUN_
RETURN_:	call	checkEOL
	ld	hl,(gosub_sp)
	ld	a,h
	or	l
	jp	z,say_what_de
	ld	sp,hl
	pop	hl
	ld	(gosub_sp),hl
	pop	hl
	ld	(cur_line),hl
	pop	de
	jp	_5NEXT_
ON_:	call	sub75
	ld	a,h
	or	l
	jr	z,_1ON_
	push	hl
	ld	hl,ong_tok+1
	jr	_1FOR_
_1ON_:	call	sub42
	rst	sub07
on_goto:	pop	hl
	call	sub41
_1on_goto:	push	de
	jp	_1GOTO_
on_gosub:	pop	hl
	call	sub41
	ld	(tmpish),hl
	call	sub108
	ld	hl,(tmpish)
	jr	_1GOSUB_
sub41:	dec	l
	jr	z,_2sub41
_1sub41:	ld	a,(de)
	cp	00dh
	jr	z,_1ON_
	cp	03ah
	jr	z,_1ON_
	inc	de
	cp	02ch
	jr	z,sub41
	jr	_1sub41
_2sub41:	call	sub141
sub42:	ld	a,(de)
	cp	03ah
	ret	z
	cp	00dh
	ret	z
	inc	de
	jr	sub42
FOR_:	call	sub108
	call	sub83
	ld	(for_sp),hl
	ld	hl,to_tok+1
_1FOR_:	jp	_1exec
TO_:	call	sub73
	ld	(for_to),hl
	ld	hl,step_tok+1
	jr	_1FOR_
STEP_:	call	sub73
	jr	_1for_top
for_top:	ld	hl,1
_1for_top:	ld	(for_a),hl
	ld	hl,(cur_line)
	ld	(for_b),hl
	ex	de,hl
	ld	(for_c),hl
	ld	bc,10
	ld	hl,(for_sp)
	ex	de,hl
	ld	h,b
	ld	l,b
	add	hl,sp
_2for_top:	ld	a,009h
	ld	a,(hl)
	inc	hl
	or	(hl)
	jr	z,_3for_top
	ld	a,(hl)
	dec	hl
	cp	d
	jr	nz,_2for_top+1
	ld	a,(hl)
	cp	e
	jr	nz,_2for_top+1
	ex	de,hl
	ld	hl,0
	add	hl,sp
	ld	b,h
	ld	c,l
	ld	hl,10
	add	hl,de
	call	copyDEtoHL
	ld	sp,hl
_3for_top:	ld	hl,(for_c)
	ex	de,hl
	rst	sub07
NEXT_:	rst	lkvar
	jp	c,say_what_de
	ld	(tmpish),hl
_1NEXT_:	push	de
	ex	de,hl
	ld	hl,(for_sp)
	ld	a,h
	or	l
	jp	z,say_what
	rst	cpHL_DE
	jr	z,_2NEXT_
	pop	de
	call	sub107
	ld	hl,(tmpish)
	jr	_1NEXT_
_2NEXT_:	call	sub113
	call	sub115
	ex	de,hl
	ld	hl,(for_a)
	push	hl
	add	hl,de
	push	hl
	call	sub117
	ld	hl,(for_sp)
	call	sub114
	pop	de
	ld	hl,(for_to)
	pop	af
	or	a
	jp	p,_3NEXT_
	ex	de,hl
_3NEXT_:	ld	a,h
	xor	d
	jp	p,_4NEXT_
	ex	de,hl
_4NEXT_:	rst	cpHL_DE
	pop	de
	jr	c,_5NEXT_
	ld	hl,(for_b)
	ld	(cur_line),hl
	jr	_3for_top
_5NEXT_:	call	sub107
	rst	sub07
REM_:	ld	hl,0
	jr	_1IF_
IF_:	call	sub73
_1IF_:	ld	a,h
	or	l
	jr	nz,_2IF_
	call	eolfindHL
	jp	nc,_3RUN_
	jp	ready
_2IF_:	ld	hl,then_tok+1
	jp	_1exec
THEN_:	call	getint
	jp	nz,_1on_goto
statement2:	jp	statement
_1statement2:	ld	sp,(tmpish)
	pop	hl
	ld	(cur_line),hl
	pop	de
INPUT_:	rst	lkchar
	defb	'#',_1INPUT_-$-1
	call	casloadblock
	push	de
	ld	hl,(cur_line)
	push	hl
	jr	_3INPUT_
_1INPUT_:	push	de
	call	strlit
	jr	_2INPUT_
	rst	lkchar
	defb	';',_4INPUT_-$-1
_2INPUT_:	ld	hl,(cur_line)
	push	hl
	ld	hl,_1INPUT_
	ld	(cur_line),hl
	ld	(tmpish),sp
	push	de
	ld	a,03fh
	call	sub93
	pop	de
_3INPUT_:	jp	_1RESTORE_
_4INPUT_:	pop	af
	jr	_3LET_
sub53:	jp	z,_1sub83
	rst	skipspace
_1sub53:	ld	a,(de)
	cp	00dh
	jr	z,_2sub53
	cp	022h
	jr	z,_3sub53
	cp	02ch
	jr	z,_2sub53
	ld	(hl),a
	inc	hl
	inc	de
	ld	a,l
	and	00fh
	jr	z,_5sub53
	jr	_1sub53
_2sub53:	ld	(hl),000h
	inc	hl
	ld	a,l
	and	00fh
	jr	nz,_2sub53
	ret
_3sub53:	inc	de
_4sub53:	ld	a,(de)
	cp	00dh
	jr	z,_2sub53
	inc	de
	cp	022h
	jr	z,_2sub53
	ld	(hl),a
	inc	hl
	ld	a,l
	and	00fh
	jr	nz,_4sub53
_5sub53:	ld	a,(de)
	cp	02ch
	ret	z
	cp	00dh
	ret	z
	inc	de
	jr	_5sub53
sub54:	rst	lkvar
	ret	c
	dec	de
	ld	a,(de)
	inc	de
	cp	029h
	ret	z
	ld	a,(de)
	cp	024h
	jr	z,_1sub54
	xor	a
	ret
_1sub54:	ld	a,l
	cp	007h
	jp	nc,say_what_de
	inc	de
	sla	a
	sla	a
	add	a,070h
	ld	l,a
	and	a
	ret
assign:	ld	a,(de)
	cp	00dh
	jr	z,_1LET_
LET_:	call	sub54
	jr	c,_3LET_
	push	af
	rst	lkchar
	defb	'=',_3LET_-$-1
	pop	af
	call	sub53
_1LET_:	rst	sub07
_2LET_:	pop	hl
	ld	(cur_line),hl
_3LET_:	jp	say_what_de
RESTORE_:	ld	hl,0
	ld	(data_ptr),hl
	rst	sub07
_1RESTORE_:	call	sub54
	jr	c,_2LET_
	push	de
	ld	de,input_buffer
_2RESTORE_:	call	sub53
	ld	(pnum_ptr),de
	pop	de
	rst	lkchar
	defb	',',_5READ_-$-1
	call	sub54
	jr	c,_2LET_
	push	de
	push	af
	ld	de,(pnum_ptr)
	rst	lkchar
	defb	',',_7READ_-$-1
	pop	af
	jr	_2RESTORE_
READ_:	call	sub54
	push	de
	jr	c,_8READ_
	push	af
	ld	de,(data_ptr)
	ld	a,d
	or	e
	jr	nz,_3READ_
	ld	de,basic_mem
_1READ_:	push	hl
	call	sub61
	pop	hl
	jr	c,_9READ_
_2READ_:	pop	af
	ld	bc,(cur_line)
	push	bc
	ld	bc,0
	ld	(cur_line),bc
	call	sub53
	pop	bc
	ld	(cur_line),bc
	ld	(data_ptr),de
	pop	de
	rst	lkchar
	defb	',',_6READ_-$-1
	jr	READ_
_3READ_:	rst	lkchar
	defb	',',_4READ_-$-1
	jr	_2READ_
_4READ_:	rst	lkchar
	defb	00dh,_7READ_-$-1
	jr	_1READ_
_5READ_:	pop	hl
	ld	(cur_line),hl
	pop	af
_6READ_:	rst	sub07
_7READ_:	pop	af
_8READ_:	jp	say_what
_9READ_:	pop	af
	jp	say_how
DATA_:	xor	a
	ret
find_data:	ld	a,(de)
	inc	de
	cp	00dh
	jr	nz,find_data
sub61:	inc	de
	inc	de
	ld	hl,(freemem)
	rst	cpHL_DE
	ret	c
	ld	hl,data_tok-1
	jr	_1sub67
	if	model == 1
cont_expr:	call	sub67
	jp	sub117
	endif
	if	model == 3
expr:	call	sub68
	call	sub67
	ld	h,000h
	jp	sub117
	endif
gt_:	rst	lkchar
	defb	'=',_1gt-$-1
	call	sub66
	ret	c
	jr	_1sub66
_1gt:	call	sub66
	ret	z
	ret	c
	jr	_1sub66
lt_:	rst	lkchar
	defb	'=',_1lt-$-1
	call	sub66
	if	model == 1
	ld	hl,1
	ret	z
	ret	c
	ld	hl,0
	endif
	if	model == 3
	ld	l,001h
	ret	z
	ret	c
	dec	l
	endif
	ret
_1lt:	rst	lkchar
	defb	'>',_1eq-$-1
	call	sub66
	ret	z
	jr	_1sub66
eq_:	call	sub66
	ret	nz
	jr	_1sub66
_1eq:	call	sub66
	ret	nc
	jr	_1sub66
; This has effect of dropping out of execution and listing the current line.
prog_sn:	pop	af
	ret
sub66:	call	sub68
	call	sub125
	if	model == 1
	ld	hl,0
	endif
	if	model == 3
	ld	l,000h
	endif
	ret
_1sub66:
	if	model == 1
	ld	hl,1
	endif
	if	model == 3
	ld	l,001h
	endif
	ret
sub67:	ld	hl,op_tok+1
_1sub67:	jp	_1exec
sub68:	rst	lkchar
	defb	'-',_1sub68-$-1
	ld	hl,0
	call	sub117
	jr	_5sub68
_1sub68:	rst	lkchar
	defb	'+',_2sub68-$-1
_2sub68:	call	sub69
_3sub68:	rst	lkchar
	defb	'+',_4sub68-$-1
	call	sub69
	call	sub127
	jr	_3sub68
_4sub68:	rst	lkchar
	defb	'-',_1sub72-$-1
_5sub68:	call	sub69
	call	sub126
	jr	_3sub68
sub69:	call	sub70
_1sub69:	rst	lkchar
	defb	'*',_2sub69-$-1
	call	sub70
	call	sub121
	jr	_1sub69
_2sub69:	rst	lkchar
	defb	'/',_1sub72-$-1
	call	sub70
	call	sub123
	jr	_1sub69
sub70:	ld	hl,func_tok+1
	jr	_1sub67
expterm:	rst	lkvar
	jr	c,_1expterm
	jp	sub113
_1expterm:	call	sub10
	ret	nz
sub72:	rst	lkchar
	defb	'(',_2sub72-$-1
	call_expr
	rst	lkchar
	defb	')',_2sub72-$-1
_1sub72:	ret
_2sub72:	jp	say_what_de
sub73:	call_expr
sub74:	jp	sub115
sub75:	call	sub73
	bit	7,h
	jp	nz,say_how_de
	ret
sub76:	call	sub72
	jr	sub74
ABS_:	call	sub72
	res	7,(ix-001h)
	ret
MEM_:	push	de
	ld	de,(freemem)
	ld	hl,(memtop)
	xor	a
	sbc	hl,de
	pop	de
	jr	_1INT_
INT_:	call	sub72
	call	sub74
_1INT_:	jp	sub117
RESET_:	ld	a,080h
	jr	_1POINT_
SET_:	ld	a,001h
	jr	_1POINT_
POINT_:	ld	a,000h
_1POINT_:	and	a
	push	af
	rst	lkchar
	defb	'(',_6POINT_-$-1
	call	sub75
	push	hl
	rst	lkchar
	defb	',',_6POINT_-$-1
	call	sub75
	rst	lkchar
	defb	')',_6POINT_-$-1
	ld	bc,sub07
	and	a
_2POINT_:	sbc	hl,bc
	jr	nc,_2POINT_
	add	hl,bc
	ld	a,l
	ld	h,0ffh
_3POINT_:	inc	h
	sub	003h
	jr	nc,_3POINT_
	add	a,003h
	pop	bc
	ld	b,h
	sla	c
	rr	b
	rr	c
	rr	b
	rr	c
	rla
	inc	a
	scf
	ld	h,000h
_4POINT_:	rl	h
	dec	a
	jr	nz,_4POINT_
	ld	a,b
	or	0fch
	and	03fh
	ld	b,a
	ld	a,(bc)
	bit	7,a
	jr	nz,_5POINT_
	ld	a,080h
	ld	(bc),a
_5POINT_:	pop	af
	ld	a,(bc)
	jr	z,_7POINT_
	jp	p,_9POINT_
	ld	a,h
	cpl
	ld	h,a
	ld	a,(bc)
	and	h
	ld	(bc),a
	rst	sub07
_6POINT_:	jr	say_what_de
_7POINT_:	and	h
	ld	hl,0
	jr	z,_8POINT_
	inc	l
_8POINT_:	jp	sub117
_9POINT_:	or	h
	ld	(bc),a
	rst	sub07
sub83:	rst	lkvar
	jr	c,say_what_de
	rst	lkchar
	defb	'=',say_what_de-$-1
_1sub83:	push	hl
	call_expr
	jp	_1sub113
sub84:	rst	lkchar
	defb	':',_1sub84-$-1
	pop	af
	jp	statement
_1sub84:	rst	lkchar
	defb	00dh,_2sub84-$-1
	pop	af
	jp	_1RUN_
_2sub84:	ret
; Converts ascii int at DE into HL and errors if not last thing in line.
getintEOL:	call	getint
; Insists only whitespace remains in line.  WHAT? if not
checkEOL:	rst	skipspace
	cp	00dh
	ret	z
say_what_de:	push	de
say_what:	ld	de,msg_WHAT
errmsg:
	if	model == 3
	xor	a
	ld	(outdev),a
	endif
	call	print
	ld	de,(cur_line)
	ld	a,d
	or	e
	jr	z,ready2
	inc	de
	ld	a,(de)
	dec	de
	or	a
	jp	m,_1statement2
	pop	hl
	ld	a,(hl)
	push	af
	sub	a
	ld	(hl),a
	call	sub104
	dec	de
	pop	af
	ld	(de),a
	ld	a,03fh
	rst	putch
	sub	a
	call	print
ready2:	jp	ready
say_sorry_de:	push	de
say_sorry:	ld	de,msg_SORRY
	jr	errmsg
; Displays > prompt and polls for input.
getline:	ld	a,03eh
sub93:
	if	model == 1
	rst	putch
	endif
	if	model == 3
	rst	vidputc
	endif
	ld	de,input_buffer
_1sub93:	call	kbscan
	jr	z,_1sub93
	cp	00dh
	jr	z,_2sub93
	cp	01dh
	jr	z,_3sub93
	cp	003h
	jr	z,ready2
	cp	020h
	jr	c,_1sub93
_2sub93:	ld	(de),a
	inc	de
	cp	00dh
	ret	z
	ld	a,e
	cp	0f3h
	jr	nz,_1sub93
	ld	a,01dh
	rst	putch
_3sub93:	ld	a,e
	cp	0ach
	jr	z,getline
	dec	de
	jr	_1sub93
; Find line number HL.
findline:	ld	de,basic_mem
; Find line number HL starting at position DE.
; Carry set if line not found but does point at line just after where
; line HL would be.  Returns NZ if not exact line number match.
findlineDE:	push	hl
	ld	a,d
	cp	042h
	jr	c,ready2
	ld	hl,(freemem)
	dec	hl
	rst	cpHL_DE
	pop	hl
	ret	c
	ld	a,(de)
	sub	l
	ld	b,a
	inc	de
	ld	a,(de)
	sbc	a,h
	jr	c,_1skipfindHL
	dec	de
	or	b
	ret
; Skip full line at DE, search for line HL.
skipfindHL:	inc	de
_1skipfindHL:	inc	de
; Go to end of line then search for line HL.
eolfindHL:	ld	a,(de)
	cp	00dh
	jr	nz,_1skipfindHL
	inc	de
	jr	findlineDE
; Print string from DE until $0 or $d (the latter will be printed).
print:	xor	a
sub99:	ld	b,a
_1sub99:	ld	a,(de)
	inc	de
	cp	b
	ret	z
	rst	putch
	cp	00dh
	jr	nz,_1sub99
	ret
; Process a string literal (double quotes)
strlit:	rst	lkchar
	defb	'"',_1strlit-$-1
	ld	a,022h
	call	sub99
	cp	00dh
	pop	hl
	jp	z,_1RUN_
	inc	hl
	inc	hl
	jp	(hl)
_1strlit:	ret
sub101:	call	sub117
sub102:	push	de
	push	bc
	push	hl
	ld	a,(ix-002h)
	cp	080h
	jr	nz,_1sub102
	ld	a,020h
	rst	putch
	ld	a,030h
	rst	putch
	jp	_18sub102
_1sub102:	ld	a,(ix-001h)
	and	a
	ld	a,020h
	jr	z,_2sub102
	ld	a,02dh
_2sub102:	rst	putch
	xor	a
	ld	(ix-001h),a
	ld	a,0ffh
_3sub102:	push	af
	ld	hl,_2rand
	call	sub124
	jr	nc,_4sub102
	call	sub120
	pop	af
	dec	a
	jr	_3sub102
_4sub102:	ld	hl,_1rand
	call	sub124
	jr	c,_5sub102
	call	sub122
	pop	af
	inc	a
	push	af
	jr	_4sub102
_5sub102:	ld	a,(ix-002h)
	neg
_6sub102:	jr	z,_7sub102
	exx
	srl	c
	rr	h
	rr	l
	exx
	dec	a
	jr	_6sub102
_7sub102:	ld	b,007h
	push	ix
	pop	hl
	ld	(hl),000h
	inc	hl
_8sub102:	ld	a,000h
	call	shiftdig
	exx
	ld	a,b
	exx
	ld	(hl),a
	inc	hl
	djnz	_8sub102
	ld	b,006h
	ld	c,000h
	dec	hl
	ld	a,(hl)
	cp	005h
_9sub102:	ccf
	ld	a,000h
	dec	hl
	adc	a,(hl)
	sla	c
	cp	00ah
	jr	c,_10sub102
	ld	a,000h
_10sub102:	ld	(hl),a
	push	af
	and	a
	jr	z,_11sub102
	set	0,c
_11sub102:	pop	af
	djnz	_9sub102
	ld	a,c
	pop	bc
	jr	c,_12sub102
	inc	b
	push	bc
	ld	b,001h
	jr	_9sub102
_12sub102:	ld	c,a
	ld	a,b
	inc	a
	jp	m,_13sub102
	cp	007h
	jr	nc,_13sub102
	ld	b,a
	call	sub103
	jr	_18sub102
_13sub102:	push	bc
	ld	b,001h
	call	sub103
	ld	a,045h
	rst	putch
	pop	bc
	bit	7,b
	ld	a,02bh
	jr	z,_14sub102
	ld	a,02dh
	rst	putch
	ld	a,b
	neg
	jr	_15sub102
_14sub102:	rst	putch
	ld	a,b
_15sub102:	ld	b,000h
_16sub102:	cp	00ah
	jr	c,_17sub102
	add	a,0f6h
	inc	b
	jr	_16sub102
_17sub102:	or	030h
	ld	c,a
	ld	a,b
	or	030h
	rst	putch
	ld	a,c
	rst	putch
_18sub102:	ld	a,020h
	rst	putch
	pop	hl
	pop	bc
	pop	de
	ld	bc,-5
	add	ix,bc
	ret
sub103:	inc	b
_1sub103:	dec	b
	jr	nz,_2sub103
	ld	a,02eh
	rst	putch
_2sub103:	ld	a,(hl)
	or	030h
	rst	putch
	inc	hl
	srl	c
	jr	nz,_1sub103
	dec	b
	dec	b
	ret	m
	inc	b
	jr	sub103
sub104:	ld	a,(de)
	ld	l,a
	inc	de
	ld	a,(de)
	ld	h,a
	inc	de
	call	sub101
	jp	print
; Memory copy from DE to BC until DE reaches HL (if DE == HL does nothing)
copyDEtoBC:	rst	cpHL_DE
	ret	z
	ld	a,(de)
	ld	(bc),a
	inc	de
	inc	bc
	jr	copyDEtoBC
; Memory copy from DE to HL until DE reaches BC (if BC == DE does nothing)
copyDEtoHL:	ld	a,b
	sub	d
	jr	nz,_1copyDEtoHL
	ld	a,c
	sub	e
	ret	z
_1copyDEtoHL:	dec	de
	dec	hl
	ld	a,(de)
	ld	(hl),a
	jr	copyDEtoHL
sub107:	pop	bc
	pop	hl
	ld	(for_sp),hl
	ld	a,h
	or	l
	jr	z,_1sub107
	pop	hl
	ld	(for_a),hl
	pop	hl
	ld	(for_to),hl
	pop	hl
	ld	(for_b),hl
	pop	hl
	ld	(for_c),hl
_1sub107:	push	bc
	ret
sub108:	ld	hl,input_buffer+212
	ld	a,h
	cpl
	ld	h,a
	ld	a,l
	cpl
	ld	l,a
	inc	hl
	pop	bc
	add	hl,sp
	jp	nc,say_sorry_de
	ld	hl,(for_sp)
	ld	a,h
	or	l
	jr	z,_1sub108
	ld	hl,(for_c)
	push	hl
	ld	hl,(for_b)
	push	hl
	ld	hl,(for_to)
	push	hl
	ld	hl,(for_a)
	push	hl
	ld	hl,(for_sp)
_1sub108:	push	hl
	push	bc
	ret
; Continuing putch; jump taken if cassette is off.
; Obviously the cassette on flag redirects output to the cassette.
cont_putch:
	if	model == 1
	jr	z,vdchar
	endif
	if	model == 3
	exx
	jr	z,not_casputc
	endif
	ex	af,af'
	ld	de,(pnum_ptr)
	ld	(de),a
	inc	de
	ld	(pnum_ptr),de
	cp	00dh
	exx
	ret	nz
	push	de
	exx
	ld	hl,input_buffer
	call	caswriteblock
	pop	de
	ret
	if	model == 3
not_casputc:	ld	a,(outdev)
	and	a
	jr	z,vdchar
lputc:	in	a,(0f8h)
	and	0f0h
	cp	030h
	jr	nz,lputc
	ex	af,af'
	out	(0f8h),a
	exx
	ret
	endif
vdchar:	ld	hl,(cursor)
	ex	af,af'
	push	af
	cp	020h
	jp	m,vdctlchar
	ld	(hl),a
	inc	hl
checkscroll:	ld	a,h
	cp	040h
	jr	nz,showcursor
	ld	de,03c00h
	ld	hl,03c40h
	ld	bc,03c0h
	ldir
	ex	de,hl
	call	cleartoEOL
	ld	hl,03fc0h
showcursor:	ld	(hl),05fh
	ld	(cursor),hl
	pop	af
	exx
	ret
; Character $0d means clear to end of line and move to next line.
vdctlchar:	cp	00dh
	jr	nz,not_newline
	call	cleartoEOL
	jr	checkscroll
; Character $0c means clear screen, home cursor.
not_newline:	cp	00ch
	jr	nz,not_cls
	ld	hl,03c00h
linelp:	call	cleartoEOL
	ld	a,h
	cp	040h
	jr	nz,linelp
	ld	hl,03c00h
	jr	showcursor
; Character $1d means backspace.
not_cls:	cp	01dh
	jr	nz,showcursor
; Any other character < $20 is shown as space.
	ld	(hl),020h
	dec	hl
	jr	showcursor
cleartoEOL:	ld	(hl),020h
	inc	hl
	ld	a,l
	and	03fh
	jr	nz,cleartoEOL
	ret
; Returns byte in A register and displays it at current cursor.
; A = 0 if no key.
; About 122 bytes for a keyboard scan; pretty good.
kbscan:	ld	a,(0387fh)
	and	a
	ret	z
	exx
	call	get_key
	exx
	rst	putch
	and	a
	push	af
; A side effect is that holding any key while a program is running
; will pause it.
wait_release:	ld	a,(0387fh)
	and	a
	jr	nz,wait_release
	pop	af
	ret
;  @   A   B   C   D   E   F   G
;  H   I   J   K   L   M   N   O
;  P   Q   R   S   T   U   V   W
;  X   Y   Z
;  0   1   2   3   4   5   6   7
;  8   9   :   ;   ,   -   .   /
;  ENT CLR BRK UP  DN   LT  RT SPC
;  shift
;
; First we delay for a bit (to avoid bounce?)
; That 'inc e' in there is unecessarily frugal!
; We only scan 7 rows in the loop.
get_key:	ld	b,0ffh
delay:	djnz	delay
	ld	de,keycolstart
	ld	hl,03801h
	ld	a,000h
scan_row:	or	(hl)
	jr	nz,got_key
	inc	e
	sla	l
	jp	p,scan_row
	exx
	pop	af
	jr	kbscan
got_key:	ex	de,hl
	ld	b,(hl)
scan_column:	inc	b
	srl	a
	jr	nz,scan_column
	ld	a,b
	cp	040h
	jr	nc,alpha_key
; Checking for <=>?@ (hmmm, only @ can come from the matrix).
	cp	03ch
	jr	nc,at_key_misc
	cp	030h
	jr	nc,digit_colon_semi
	ld	hl,specialkeys
find_special:	inc	hl
	dec	b
	jr	nz,find_special
	ld	b,(hl)
	call	check_shift
	ret	nz
; If no shift, leave most alone but the up, down, left, right keys
; map to $1b, $1c, $1d, $1e which is why $1d is backspace.
	and	03fh
	ret
alpha_key:	call	check_shift
	ret	z
; Hey, shift maps alpha keys into control characters 1 to 27.
; So shift-M is the same as enter, shift-L is clear, shift-C is break.  Cool.
; The Level I manual warns not to use the shift key; this is why.
; However, shift-H is _not_ backspace because that is $1D in our world.
	and	03fh
	ret
digit_colon_semi:
	call	check_shift
	ret	z
; Map '0' to ' ', '1' to '!', etc.
maskit:	and	02fh
	ret
; All this ends up doing is turning shift-@ into a 0.
at_key_misc:	call	check_shift
	ret	nz
	jr	maskit
; Return NZ if shift pressed.
check_shift:	ld	a,(03880h)
	and	a
	ld	a,b
	ret
def_keycol	macro
keycolstart:	ascii	'?'
	ascii	'G'
	ascii	'O'
	ascii	'W'
	ascii	'/'
	ascii	'7'
; Enter, clear, break, up, down, left, right, space-bar
specialkeys:	ascii	0
	ascii	13
	ascii	12
	ascii	3
	ascii	'['
	ascii	92
	ascii	']'
	ascii	'^'
	ascii	' '
	endm
	if	model == 1
; Ohmigosh; a wasted byte!
	ret
	def_keycol
	endif
	if	model == 3
	def_print_tok
	endif
data_tok:	ascii	'DATA'
	drow	DATA_|8000h
	drow	find_data|8000h
sub113:	push	de
	push	hl
	push	af
	ld	bc,4
	push	ix
	pop	de
	ldir
	rl	(ix+002h)
	rl	(ix+003h)
	ld	a,b
	rra
	ld	(ix+004h),a
	scf
	rr	(ix+002h)
	ld	c,005h
	add	ix,bc
	pop	af
	pop	hl
	pop	de
	ret
_1sub113:	pop	hl
sub114:	ld	bc,-5
	add	ix,bc
	ld	bc,4
	push	de
	push	hl
	ex	de,hl
	push	ix
	pop	hl
	ldir
	ex	de,hl
	dec	hl
	dec	hl
	rl	(hl)
	inc	hl
	ld	a,(ix+004h)
	rla
	rr	(hl)
	dec	hl
	rr	(hl)
	pop	hl
	pop	de
	ret
sub115:	exx
	ld	bc,-5
	add	ix,bc
	ld	de,0
	ld	a,(ix+003h)
	ld	c,(ix+004h)
	cp	080h
	jr	z,_6sub115
	cp	001h
	jp	m,_1sub115
	cp	010h
	jp	m,_2sub115
	exx
	jp	say_how_de
_1sub115:	ld	a,0ffh
	jr	_4sub115
_2sub115:	ld	b,a
	ld	a,(ix+000h)
	ld	l,(ix+001h)
	ld	h,(ix+002h)
_3sub115:	sla	a
	rl	l
	rl	h
	rl	e
	rl	d
	djnz	_3sub115
_4sub115:	sla	c
	jr	nc,_6sub115
	or	h
	or	l
	jr	z,_5sub115
	inc	de
_5sub115:	call	sub119
_6sub115:	push	de
	exx
	pop	hl
	ret
sub116:	ld	hl,10
sub117:	push	de
	ex	de,hl
	ld	bc,10
	add	ix,bc
	call	sub118
	push	de
	ld	h,000h
	rr	h
	ld	l,010h
	exx
	pop	de
	ld	l,000h
	ld	h,e
	ld	c,d
	call	normCHL
	jr	_1sub123
sub118:	xor	a
	add	a,d
	ret	p
sub119:	ld	a,e
	neg
	ld	e,a
	ld	a,d
	cpl
	ccf
	adc	a,000h
	ld	d,a
	scf
	ret
sub120:	call	sub116
sub121:	call	sub136
	jr	z,_2sub126
	cp	e
	jp	z,_2sub128
	call	sub129
	jr	_1sub123
sub122:	call	sub116
sub123:	call	sub136
	jr	z,_2sub126
	cp	e
	jp	z,say_how
	call	sub130
_1sub123:	jr	_3sub128
sub124:	call	sub113
	call	sub136
	ld	bc,-5
	jr	_1sub125
sub125:	call	sub136
	ld	bc,-10
_1sub125:	add	ix,bc
	cp	l
	call	sub131
	pop	de
	ret
sub126:	call	sub136
	jr	nz,_1sub126
	call	sub128
	jr	_4sub127
_1sub126:	cp	e
_2sub126:	jr	z,_4sub128
	xor	d
	ld	d,a
	jr	_1sub127
	if	model == 1
	call	sub113
	endif
sub127:	call	sub136
	jr	z,_1sub128
	cp	e
	jr	z,_4sub128
_1sub127:	call	sub132
	jr	z,_3sub127
	jr	nc,_2sub127
	ex	de,hl
	exx
	ex	de,hl
	ld	a,c
	ld	c,b
	ld	b,a
	exx
_2sub127:	call	sub133
	jr	_3sub128
_3sub127:	ld	a,h
	xor	d
	jr	nz,_2sub128
	ld	e,001h
	call	sub134
	jr	_3sub128
_4sub127:	ld	a,(ix-001h)
	xor	080h
	ld	(ix-001h),a
	pop	de
	ret
sub128:	push	de
_1sub128:	ld	h,d
	ld	l,e
	exx
	ld	l,e
	ld	h,d
	ld	c,b
	exx
	jr	_3sub128
_2sub128:	ld	l,080h
_3sub128:	ld	(ix-006h),h
	ld	(ix-007h),l
	exx
	ld	(ix-00ah),l
	ld	(ix-009h),h
	ld	(ix-008h),c
	exx
_4sub128:	ld	bc,-5
	add	ix,bc
	pop	de
	ret
sub129:	ld	a,h
	xor	d
	ld	h,a
	dec	e
	push	hl
	push	bc
	ld	b,018h
	ld	l,(ix-00ah)
	ld	h,(ix-009h)
	ld	c,(ix-008h)
	exx
	xor	a
	ld	l,a
	ld	h,a
	ld	c,a
_1sub129:	exx
	srl	c
	rr	h
	rr	l
	exx
	jr	nc,_2sub129
	add	hl,de
	ld	a,c
	adc	a,b
	ld	c,a
_2sub129:	exx
	djnz	_3sub129
	pop	bc
	pop	hl
	exx
	jr	_3sub130
_3sub129:	exx
	rr	c
	rr	h
	rr	l
	jr	_1sub129
sub130:	ld	a,e
	neg
	ld	e,a
	ld	a,h
	xor	d
	ld	h,a
	push	hl
	push	bc
	ld	b,019h
	exx
_1sub130:	sbc	hl,de
	ld	a,c
	sbc	a,b
	ld	c,a
	jr	nc,_2sub130
	add	hl,de
	adc	a,b
	ld	c,a
_2sub130:	exx
	ccf
	adc	hl,hl
	rl	c
	djnz	_4sub130
	push	hl
	push	bc
	exx
	pop	bc
	pop	hl
	exx
	pop	bc
	pop	hl
	exx
_3sub130:	jr	_3sub133
_4sub130:	exx
	add	hl,hl
	rl	c
	jr	nc,_1sub130
	ccf
	sbc	hl,de
	ld	a,c
	sbc	a,b
	ld	c,a
	or	a
	jr	_2sub130
sub131:	jr	z,_1sub131
	cp	e
	jr	z,_3sub131
	ld	a,h
	xor	d
	call	z,sub132
	jr	_2sub131
_1sub131:	cp	e
	ret	z
	scf
	bit	7,d
	jr	_4sub131
_2sub131:	ret	z
_3sub131:	bit	7,h
_4sub131:	jr	nz,_5sub131
	rra
	scf
	rl	a
	ret
_5sub131:	ccf
	ret
sub132:	ld	a,l
	sub	e
	jr	z,_2sub132
	jp	po,_1sub132
	neg
_1sub132:	rlca
	ret
_2sub132:	exx
	ld	a,c
	cp	b
	jr	nz,_3sub132
	ld	a,h
	cp	d
	jr	nz,_3sub132
	ld	a,l
	cp	e
_3sub132:	exx
	ret
sub133:	ld	a,l
	sub	e
	jr	z,_2sub133
	cp	018h
	ret	nc
	exx
_1sub133:	srl	b
	rr	d
	rr	e
	dec	a
	jr	nz,_1sub133
	exx
_2sub133:	ld	e,000h
	ld	a,h
	xor	d
	jp	m,_2sub134
	exx
	add	hl,de
	ld	a,c
	adc	a,b
	ld	c,a
_3sub133:	jr	nc,_4sub133
	rr	c
	rr	h
	rr	l
	scf
_4sub133:	exx
sub134:	ld	a,l
	adc	a,e
_1sub134:	jp	pe,_4normCHL
	ld	l,a
	ret
_2sub134:	exx
	sbc	hl,de
	ld	a,c
	sbc	a,b
	ld	c,a
normCHL:	ld	b,018h
	xor	a
	inc	c
	dec	c
_1normCHL:	jp	m,_3normCHL
	dec	a
	add	hl,hl
	rl	c
	djnz	_1normCHL
_2normCHL:	ld	l,080h
	ret
_3normCHL:	exx
	add	a,l
	jr	_1sub134
_4normCHL:	ld	a,h
	or	a
	jp	m,_2normCHL
	pop	af
	jp	say_how
sub136:	pop	hl
	push	de
	push	hl
	ld	d,(ix-001h)
	ld	e,(ix-002h)
	exx
	ld	e,(ix-005h)
	ld	d,(ix-004h)
	ld	b,(ix-003h)
	exx
	ld	h,(ix-006h)
	ld	l,(ix-007h)
	exx
	ld	l,(ix-00ah)
	ld	h,(ix-009h)
	ld	c,(ix-008h)
	exx
	ld	a,080h
	cp	l
	ret
RND_:	call	sub76
	ld	a,h
	or	l
	jp	z,sub138
	bit	7,h
	jp	nz,say_how_de
	call	sub117
	call	sub138
	call	sub121
	call	sub115
	inc	hl
	jp	sub117
sub138:	push	de
	exx
	ld	hl,rnd_seed
	ld	e,(hl)
	inc	hl
	ld	d,(hl)
	inc	hl
	ld	b,(hl)
	exx
	call	clr24b
	ld	hl,rand
	ld	c,003h
_1sub138:	ld	b,008h
	ld	d,(hl)
_2sub138:	exx
	add	hl,hl
	rl	c
	exx
	rl	d
	jr	nc,_3sub138
	exx
	add	hl,de
	ld	a,c
	adc	a,b
	ld	c,a
	exx
_3sub138:	djnz	_2sub138
	inc	hl
	dec	c
	jr	nz,_1sub138
	ld	hl,0
	exx
	ld	de,rnd_seed
	ld	a,l
	add	a,065h
	ld	(de),a
	inc	de
	ld	l,a
	ld	a,h
	adc	a,0b0h
	ld	(de),a
	inc	de
	ld	h,a
	ld	a,c
	adc	a,005h
	ld	(de),a
	ld	c,a
	call	normCHL
	ld	bc,10
	add	ix,bc
	jp	_3sub128
rand:	defb	040h
	defb	0e6h
	defb	04dh
_1rand:	defb	000h
	defb	000h
	defb	080h
	defb	000h
_2rand:	defb	0cch
	defb	0cch
	defb	0cch
sub140:	ld	a,(hl)
sub141:	call	getint
	ret	nz
say_what_de3:	jp	say_what_de
; Convert ascii number to integer in HL but only 0 to 32767.
; B is the number of digits with Z set if zero digits.
getint:	call	clr24b
	ld	hl,0
	ld	b,l
	rst	skipspace
_1getint:	call	getdig
	jr	c,_3getint
	inc	b
	call	shiftdig
	jr	nc,_1getint
_2getint:	jp	say_how_de
_3getint:	exx
	push	hl
	ld	a,c
	bit	7,h
	exx
	pop	hl
	jr	nz,_2getint
	and	a
	jr	nz,_2getint
	ld	a,b
	and	a
	ret
CLOAD_:	call	casloadblock
	ld	(freemem),hl
	jr	nz,say_what_de3
ready3:	jp	ready
; On return, HL = last + 1 address.  Z set if checksum OK, NZ otherwise.
casloadblock:	call	cton
	push	de
	xor	a
_1casloadblock:	call	getbit
	cp	0a5h
	jr	nz,_1casloadblock
	ld	a,02ah
	ld	(03c00h),a
	ld	(03c01h),a
	call	gtbyte
	ld	d,a
	call	gtbyte
	ld	e,a
	call	gtbyte
	ld	h,a
	call	gtbyte
	ld	l,a
	ld	c,000h
_2casloadblock:	call	gtbyte
	ld	(de),a
	inc	de
	cp	00dh
	jr	nz,_3casloadblock
	push	af
	ld	a,(03c01h)
	xor	00ah
	ld	(03c01h),a
	pop	af
_3casloadblock:	add	a,c
	ld	c,a
	rst	cpHL_DE
	jr	nc,_2casloadblock
	push	hl
	call	ctoff
	pop	hl
	pop	de
	ld	a,c
	and	a
	ret
CSAVE_:	call	cton
	ld	hl,basic_mem
	ld	de,(freemem)
	call	caswriteblock
	if	model == 1
	jp	ready
	endif
	if	model == 3
	jp	ready3
	endif
; HL = start address, DE = last+1 address.
	if	model == 1
caswriteblock:	ld	a,080h
	push	bc
_1caswriteblock:
	ex	af,af'
	xor	a
	call	putbyte
	ex	af,af'
	dec	a
	jr	nz,_1caswriteblock
	endif
	if	model == 3
caswriteblock:	ld	b,080h
_1caswriteblock:
	xor	a
	call	putbyte
	djnz	_1caswriteblock
	endif
	ld	a,0a5h
	call	putbyte
	ld	a,h
	call	putbyte
	ld	a,l
	call	putbyte
	if	model == 1
	pop	bc
	endif
	ld	a,d
	call	putbyte
	ld	a,e
	call	putbyte
	ld	c,000h
_2caswriteblock:
	ld	a,(hl)
	call	putbyte
	inc	hl
	rst	cpHL_DE
	jr	nz,_2caswriteblock
	ld	a,c
	neg
	call	putbyte
	if	model == 1
	call	ctoff
	ret
	endif
	if	model == 3
	jr	ctoff
	endif
; Read single bit from tape and shift into A register.
	if	model == 1
getbit:	exx
	ex	af,af'
_1getbit:	in	a,(0ffh)
	rla
	jr	nc,_1getbit
	ld	b,07ch
_2getbit:	djnz	_2getbit
	call	gtstat
	ld	b,0f8h
_3getbit:	djnz	_3getbit
	in	a,(0ffh)
	ld	b,a
	ex	af,af'
	rl	b
	rla
	push	af
	call	gtstat
	pop	af
	exx
	ret
	endif
	if	model == 3
getbit:	exx
	ld	c,a
_1getbit:	in	a,(0ffh)
	rla
	jr	nc,_1getbit
	ld	b,0bbh
_2getbit:	djnz	_2getbit
	out	(0ffh),a
	ld	b,000h
_3getbit:	djnz	_3getbit
	in	a,(0ffh)
	rla
	ld	a,c
	rla
	out	(0ffh),a
	exx
	ret
	endif
; Calls gtbit 8 times to get a full byte.
gtbyte:	ld	b,008h
_1gtbyte:	call	getbit
	djnz	_1gtbyte
	ret
putbyte:	exx
	ld	c,008h
	ld	d,a
_1putbyte:	call	putbit
	rlc	d
	jr	nc,_3putbyte
	call	putbit
_2putbyte:	dec	c
	jr	nz,_1putbyte
	ld	a,d
	exx
	add	a,c
	ld	c,a
	ret
	if	model == 1
_3putbyte:	ld	b,000h
_4putbyte:	djnz	_4putbyte
	jr	_2putbyte
putbit:	ld	hl,0fc01h
	call	cstat
	ld	b,00ah
_1putbit:	djnz	_1putbit
	ld	hl,0fc02h
	call	cstat
	ld	b,00ah
_2putbit:	djnz	_2putbit
	ld	hl,0fc00h
	call	cstat
	ld	b,0dah
_3putbit:	djnz	_3putbit
	ret
ctoff:	ld	hl,0fb00h
	jr	cstat
cton:	ld	hl,0ff04h
	call	cstat
	ret
; Returns NZ if cassette motor is on, Z if off.
gtstat:	ld	hl,0ff00h
cstat:	ld	a,(status)
	and	h
	or	l
	out	(0ffh),a
	ld	(status),a
	bit	2,a
	ret
	endif
	if	model == 3
_3putbyte:	ld	b,034h
_4putbyte:	djnz	_4putbyte
_5putbyte:	djnz	_5putbyte
	jr	_2putbyte
putbit:	ld	a,001h
	out	(0ffh),a
	ld	b,012h
_1putbit:	djnz	_1putbit
	inc	a
	out	(0ffh),a
	ld	b,012h
_2putbit:	djnz	_2putbit
	xor	a
	out	(0ffh),a
	ld	b,00dh
_3putbit:	djnz	_3putbit
_4putbit:	djnz	_4putbit
	ret
	nop
	nop
	nop
	def_keycol
ctoff:	ld	a,020h
	jr	_1cton
; And disables video waits, too!
cton:	ld	a,002h
_1cton:	out	(0ech),a
	ret
	rws_msg
	endif
	org	04000h
vA:	defs	4
vB:	defs	4
vC:	defs	4
vD:	defs	4
vE:	defs	4
vF:	defs	4
vG:	defs	4
vH:	defs	4
vI:	defs	4
vJ:	defs	4
vK:	defs	4
vL:	defs	4
vM:	defs	4
vN:	defs	4
vO:	defs	4
vP:	defs	4
vQ:	defs	4
vR:	defs	4
vS:	defs	4
vT:	defs	4
vU:	defs	4
vV:	defs	4
vW:	defs	4
vX:	defs	4
vY:	defs	4
vZ:	defs	4
cursor:	defs	2
; Pointer just past top of memory.
memtop:	defs	2
; Pointer to free memory (and/or end of basic program)
freemem:	defs	2
for_to:	defs	2
stringA:	defs	16
stringB:	defs	16
	if	model == 1
; Mirrors port $ff
status:	defs	1
	endif
	if	model == 3
; Output device; 0 == screen, 1 == printer
outdev:	defs	1
	endif
for_a:	defs	2
for_b:	defs	2
for_c:	defs	2
cont_line:	defs	2
pnum_ptr:	defs	2
tmpish:	defs	2
cont_ptr:	defs	2
cur_line:	defs	2
data_ptr:	defs	2
gosub_sp:	defs	2
for_sp:	defs	2
rnd_seed:	defs	3
	org	040ach
; 72 characters max.
; Last 10 may be used as two 5 byte floating point accumulators.
input_buffer:	defs	72
basic_mem	equ	04200h
	end	sub00