;
; SC84 Machine Code Operating System
;
; 2020-05-10
; First crack at recreating source code from  bytes OCR'd
; from the SC84 newsletter, volume 2 number 1.
;
; Assembles at https://www.asm80.com
; 
; The code shows it requires a Mostek  Serial Timer Interrupt Controller.
; 
; 2022-06-17
;
; Renamed to end in .txt (instead of .z80) so it can be read online.
; This requires the following line:
    .cpu    Z80
;
; This now creates exactly the same hex file output
; as the newsletter OCR bytes.
;


	null	equ	0
	space	equ	0x20
	esc  	equ	0x1b
	
	BEL  	equ	0x07
	BS  	equ	0x08
	FF  	equ	0x0c
	LF  	equ	0x0a
	CR	    equ	0x0d
	DEL  	equ	0x7F


    making_original_buggy_version  equ 0

; from Wireless World, October 1984, pages 21-24 and 27


;	CTRL G (BEL)	causes a 'beep'
;
;	CTRL H (BS)	backspaces the cursor one place without deleting.
;
;	CTRL J (LF)	moves the cursor down one line, scrolling the screen if necessary.
;
;	CTRL L (FF)	as for LF.
;
;	CTRL M (CR)	returns the cursor to the leftmost position of the current output line,
;			clearing any characters to the right of the original cursor position,
;			providing it was not already at the left margin.
;	DEL (hex. 07F) backspaces the cursor one position, deleting the character onto which the cursor moves.
;
;	VDUA also recognises the following ESCAPE sequences
;	(ESCAPE being the hex. character 01 B, decimal 27 or CTRL [).
;
;	ESC F	selects reverse video display of subsequent ascii codes.
;	ESC G	selects normal video display of subsequent ascii codes.
;	ESC H	moves the cursor to the top left corner of the v.d.u.
;	ESC J	erases from cursor position to end of screen
;	ESC K	erases from cursor position to end of line
;
;	ESC Y I c
;		sets the cursor position to line I, column c.
;		I and c are single hex. characters equating to
;		the desired value plus 01F, 
;		i.e. the top left corner of the v.d.u. is 020, 020 
;		and the bottom left corner (in mode 0) is 03F, 07F.


	LINE	EQU	96	; VDU chars per line
	FRAME	EQU	32	; VDU lines per frame
;;	VDU1	EQU	0xA000 - LINE + FRAME	 ; set VDU start WRONG
	VDU1	EQU	0x9400	 ; set VDU start
;;	CRTH	EQU	> (VDU1 AND 03FH)	 ; high byte of VDU start
;;	CRTL	EQU	< VDU1	 ; low byte of VDU start



	CONTRL	EQU	0E0H 		; set basic port address for I/O

	port_0xe0	equ	CONTRL + 0
	
	port_0xe4	equ	CONTRL + 4
	port_0xe5	equ	CONTRL + 5
	port_0xe6	equ	CONTRL + 6
	port_0xe7	equ	CONTRL + 7
	
	port_0xe8	equ	CONTRL + 8
	
	; MK3801 direct ports

	IDR	EQU	CONTRL + 010H	; Indirect Data Register
	GPIP	EQU	CONTRL + 011H	; General Purpose I/O-Interrupt
	IPRB	EQU	CONTRL + 012H	; Interrupt Pending Register B
	IPRA	EQU	CONTRL + 013H	; Interrupt Pending Register A
	ISRB	EQU	CONTRL + 014H	; Interrupt in-Service Register B
	ISRA	EQU	CONTRL + 015H	; Interrupt in-Service Register A
	IMRB	EQU	CONTRL + 016H	; Interrupt Mask Register B
	IMRA	EQU	CONTRL + 017H	; Interrupt Mask Register A
	PVR	EQU	CONTRL + 018H	; Pointer/Vector Register
	TABCR	EQU	CONTRL + 019H	; Timers A and B Control Register
	TBDR	EQU	CONTRL + 01AH	; Timer B Data Register
	TADR	EQU	CONTRL + 01BH	; Timer A Data Register
	UCR	EQU	CONTRL + 01CH	; USART Control Register
	RSR	EQU	CONTRL + 01DH	; Receiver Status Register
	TSR	EQU	CONTRL + 01EH	; Transmitter Status Register
	UDR	EQU	CONTRL + 01FH	; USART Data Register

	; MK3801 indirect ports

	SCR	EQU	0       ; Sync Character Register
	TDDR	EQU	1	; Timer D Data Register
	TCDR	EQU	2	; Timer C Data Register
	AER	EQU	3	; Active Edge Register
	IERB	EQU	4	; Interrupt Enable Register
	IERA	EQU	5	; Interrupt Enable Register
	DDR	EQU	6	; Data Direction Register
	TCDCR	EQU	7	; Timer C and D Control Register



	.org	0x0000 

; 0000

FIRMWARE_SIZE    equ	0x07ee

; 0000 21 12 00

	ld 	hl,FIRMWARE_TO_COPY
	ld 	de,FIRMWARE_DESTINATION
	ld 	bc,FIRMWARE_SIZE
	ldir

; 000b af      

	xor 	a		; clear A
	ld (CURDRV),a

; 000f c3 39 f8

	jp 	HIGH_ENTRY_POINT		; jump into copied code.	

; 0012

FIRMWARE_TO_COPY:

; This is actually meant to run at F800,
; so these are just the code bytes expected.
;
; Disassembling these bytes yields 
; wrong code and addresses.
; They are here just so that they can
; produce a file that can be compared with 
; an original ROM image (if/when one becomes available).
;
; These bytes were disassembled online, using:
; https://onlinedisassembler.com
; and edited to a form acceptable to 
; this online assembler:
; https://www.asm80.com
;
; See code at org $F800 later in this file.

    .phase 0xf800   ; FIRMWARE_DESTINATION

; Continue to produce code and data for loading at the current address
; but assemble instructions and define labels
; as if they originated at the given address.
; Useful when producing code that will be copied
; to a different location before being executed.

FIRMWARE_DESTINATION:

;
; Starts with a jump table:
;
;
HRESET: jp	do_HRESET
SRESET:	jp	do_SRESET
VDUA:	jp	do_VDUA
KEY1:	jp	do_KEY1
PARIN:	jp	do_PARIN
PAROUT:	jp	do_PAROUT
PRINT:	jp	do_PRINT
VDUON:	jp	do_VDUON
VDUOFF:	jp	do_VDUOFF
KEY2:	jp	do_KEY2
KEY3:	jp	do_KEY3
KEY4:	jp	do_KEY4
RESDSK:	jp	do_RESDSK
RDDSK:	jp	do_RDDSK
WRDSK:	jp	do_WRDSK
STEPR:	jp	do_STEPR
PSCROL:	jp	do_PSCROL
TIME:	jp	do_TIME
SETUP:	jp	do_SETUP


;	Function	Description
;	name
;
;	HRESET		Completely reinitializes system and returns to MCOS.
;
;	SRESET 		Reenters MCOS without resetting RSTs to default values.
;
;	VDUA 		Sends the character in A (the accumulator) to the v.d.u.
;				Can process all ascii characters (020 to 07E) as well as certain
;				control characters, escape sequences
;				and reverse-video ascii characters.
;
;	KEY1		Waits for a character to appear in the keyboard buffer, 
;				clears the buffer and returns the key code in A.
;				Processes the paging key
;
;	PARIN		Reads an 8-bit byte from the parallel input port to A.
;
;	PAROUT		Sends the contents of A to the parallel output port.
;
;	PRINT		Sends the character in A to the serial output port.
;
;	VDUON		Switches the v.d.u. into the memory map at 08000 to 09FFF.
;
;	VDUOFF		Switches the v.d.u. out of memory map.
;
;	KEY2		Tests keyboard buffer,
;				returning 000 if empty
;				or clearing the buffer and
;				returning the key code if not.
;
;	KEY3		Similar to KEY2, but processes the paging
;				character and does not clear buffer.
;
;	KEY4		Tests the keyboard buffer,
;				returning 000 if empty 
;				or 0FF if not. 
;				Does not clear the buffer.
;
;	RESDSK		Resets (to track 00) and selects the
;				specified disc unit.
;
;	RDDSK		Reads from the specified disc unit, track
;				and sector to memory.
;
;	WRDSK		Writes to the specified disc unit, track and
;				sector from memory.
;
;	STEPR		Sets the stepping rate for disc seek and
;				restore operations by supplying code 018
;				to 01B in the A register.
;				These four codes correspond to stepping rates of 
;				3, 6, 10 and 15ms respectively 
;				when the interface is in the 8 inch mode, 
;				double these times in 5.25in mode.
;				The slowest speed is the system default.
;
;	PSCROL		Sets the number of screen lines to take
;				part in v.d.u. scrolling. Scrolling always
;				occurs from the bottom of the screen, but
;				this function can be used to keep a
;				number of lines at the top of the screen
;				stationary for applications such as mixed
;				graph plotting and data output, applications 
;				progam menus and/or instructions. 
;				The number of scrolling lines is 
;				suppied in register A.
;
;	TIME		Creates a 10ms time delay.
;
;	SETUP		Sets standard v.d.u. mode (32 lines of 96 characters).
;
;
;
HIGH_ENTRY_POINT:
; 0xf839	3e	d0
	ld	a,0xd0
	out	(port_0xe4),a


do_HRESET:
	ld	hl,0x0000
	ld	de,Lff5e
; 0xf843	3e	08
	ld	a,0x08


loop_f845:
	ld	(hl),0xc3
	inc	hl
	ex	de,hl
; 0xf849	ed	a0
	ldi
; 0xf84b	ed	a0
	ldi
; 0xf84d	eb
	ex	de,hl
; 0xf84e	01	05	00
	ld	bc,5
; 0xf851	09
	add	hl,bc
; 0xf852	3d
	dec	a
	jr	nz,loop_f845


do_SRESET:	ld	sp,0
	call	subroutine_fa4b
; 0xf85b	fb
	ei
	
loop_f85c:  ;	cd	e5	fa

	call	subroutine_fae5
	cp	0x13
	jr	z,skip_f870

; 0xf863	fe	04
	cp	0x04
	jr	nz,skip_f883



; 0xf867	21	80	f7
	ld	hl,0xf780
; 0xf86a	dd	21	73	ff
	ld	ix,Lff73
; 0xf86e	18	07
	jr	skip_f877



skip_f870:
	ld	hl,0x0080
; 0xf873	dd	21	6e	ff
	ld	ix,SDEN



skip_f877:
	push	hl
; 0xf878	cd	5e	fa
	call	subroutine_fa5e
loop_f87b:
	call	do_RESDSK
	jr	nz,loop_f87b

	jp	DO_RDDSK



skip_f883:
	ld	b,a

loop_f884:
	ld	c,a
; 0xf885	cd	e5	fa
	call	subroutine_fae5
; 0xf888	fe	20
	cp	space
	jr	nz,loop_f884


; 0xf88c	79
	ld	a,c
; 0xf88d	81
	add	a,c
; 0xf88e	80
	add	a,b
; 0xf88f	fe	d8
	cp	0xd8
	jr	nz,skip_f8b2


; 0xf893	cd	76	fb
	call	subroutine_fb76
; 0xf896	e5
	push	hl
; 0xf897	cd	73	fb
	call	subroutine_fb73
; 0xf89a	c1
	pop	bc
; 0xf89b	e5
	push	hl
; 0xf89c	a7
	and	a
; 0xf89d	ed	42
	sbc	hl,bc
; 0xf89f	e3
	ex	(sp),hl
; 0xf8a0	c1
	pop	bc
; 0xf8a1	2b
	dec	hl
; 0xf8a2	cd	7f	fb
	call	subroutine_fb7f
; 0xf8a5	e5
	push	hl
; 0xf8a6	d1
	pop	de
; 0xf8a7	85
	add	a,l
; 0xf8a8	6f
	ld	l,a
	
	
; 0xf8a9	30	01
	jr	nc,skip_f8ac
	inc	h
skip_f8ac:


	ex	de,hl
; 0xf8ad	ed	b8
	lddr
; 0xf8af	c3	55	f8
	jp	do_SRESET
;
;
skip_f8b2:
	cp	0xe9
	jr	nz,skip_f8d2
	
loop_f8b6:
	call	subroutine_fb76
	call	subroutine_fb7f

	ld	(hl),a
	call	subroutine_faf4
	call	subroutine_fa4b

loop_f8c3:
	ld	a,(KBF)     ; read key
	or	a
	jr	z,loop_f8c3 ; repeat while zero
	;
	; okay, now you have a key
	;
; 0xf8c9	e6	5f
	and	0x5f
; 0xf8cb	fe	47
	cp	'G'
	jr	c,loop_f8b6
; 0xf8cf	c3	5c	f8
	jp	loop_f85c
	

skip_f8d2:
	cp	0xd5
	jr	nz,skip_f8fd
; 0xf8d6	cd	76	fb
	call	subroutine_fb76
; 0xf8d9	e5
	push	hl
; 0xf8da	e5
	push	hl
	pop	bc
; 0xf8dc	cd	73	fb
	call	subroutine_fb73
; 0xf8df	ed	42
	sbc	hl,bc
; 0xf8e1	e5
	push	hl
	pop	bc
; 0xf8e3	e1
	pop	hl
; 0xf8e4	cd	7f	fb
	call	subroutine_fb7f
; 0xf8e7	5f
	ld	e,a
; 0xf8e8	cd	7f	fb
	call	subroutine_fb7f
	call	subroutine_fba5

loop_f8ee:
	cpir
; 0xf8f0	e2	55	f8
	jp	po,do_SRESET
; 0xf8f3	2b
	dec	hl      ; predecrement hl
	ld	(hl),e
; 0xf8f5	f5
	push	af
; 0xf8f6	cd	c7	fa
	call	subroutine_fac7
; 0xf8f9	23
	inc	hl
; 0xf8fa	f1
	pop	af
; 0xf8fb	18	f1
	jr	loop_f8ee

skip_f8fd:
	cp	0xf9
	jr	nz,skip_f919
; 0xf901	cd	76	fb
	call	subroutine_fb76
; 0xf904	e5
	push	hl
; 0xf905	cd	73	fb
	call	subroutine_fb73
; 0xf908	c1
	pop	bc
	push	bc
; 0xf90a	a7
	and	a
; 0xf90b	ed	42
	sbc	hl,bc
; 0xf90d	e5
	push	hl
	pop	bc
; 0xf90f	cd	73	fb
	call	subroutine_fb73
; 0xf912	d1
	pop	de
; 0xf913	eb
	ex	de,hl
; 0xf914	ed	b0
	ldir
; 0xf916	c3	55	f8
	jp	do_SRESET
;
;
skip_f919:
	cp	0xde
	jr	nz,skip_f928
; 0xf91d	cd	76	fb
	call	subroutine_fb76
;
loop_f920:
	ld	(hl),0xff
; 0xf922	2c
	inc	l
	jr	nz,loop_f920
	jp	do_SRESET
;
;
skip_f928:
	cp	0xfc
	jr	nz,skip_f93a
; 0xf92c	21	00	00
	ld	hl,0x0000
;
loop_f92f:
	ld	(hl),0xff
	inc	hl

; 0xf932	7c
	ld	a,h     ; is h == 0xf8 ?
	cp	0xf8
	jr	nz,loop_f92f
; 0xf937	c3	3d	f8
	jp	do_HRESET      ; yes, go to hard reset.
;
;
skip_f93a:
	push	af
; 0xf93b	cd	da	fa
	call	subroutine_fada
; 0xf93e	1b
	dec	de
; 0xf93f	4a
	ld	c,d
; 0xf940	00
	nop
; 0xf941	f1
	pop	af
; 0xf942	fe	d4
	cp	0xd4
	jr	nz,skip_f996
; 0xf946	cd	76	fb
	call	subroutine_fb76
; 0xf949	cd	a5	fb
	call	subroutine_fba5
; 0xf94c	e5
	push	hl
loop_f94d:  ;	cd	38	fb
	call	subroutine_fb38
loop_f950:
	call	subroutine_fae5
; 0xf953	fe	5f
	cp	0x5f    ; '_'
	jr	nz,skip_f979
; 0xf957	2b
	dec	hl
; 0xf958	7d
	ld	a,l
; 0xf959	e6	0f
	and	0x0f    ; low nibble
; 0xf95b	fe	0f
	cp	0x0f
	jr	nz,skip_f966
	
; 0xf95f	3e	0d
	ld	a,CR
	call	do_VDUA
; 0xf964	18	e7
	jr	loop_f94d
;
;
skip_f966:
	call	subroutine_fb46
; 0xf969	3a	47	ff
	ld	a,(LPOS)
; 0xf96c	d6	05
	sub	0x05
; 0xf96e	90
	sub	b
; 0xf96f	47
	ld	b,a
loop_f970: ;	3e	7f
	ld	a,0x7f
; 0xf972	cd	60	fc
	call	do_VDUA
; 0xf975	10	f9
	djnz	loop_f970
; 0xf977	18	d7
	jr	loop_f950
;
;
skip_f979:
	cp	space
	jr	z,skip_f98f
; 0xf97d	cd	94	fb
	call	subroutine_fb94
; 0xf980	cd	85	fb
	call	subroutine_fb85
; 0xf983	77
	ld	(hl),a
; 0xf984	23
	inc	hl
; 0xf985	cd	12	fb
	call	subroutine_fb12
; 0xf988	20	c6
	jr	nz,loop_f950
; 0xf98a	cd	a5	fb
	call	subroutine_fba5
; 0xf98d	18	be
	jr	loop_f94d
skip_f98f:
	pop	hl
; 0xf990	cd	f7	fa
	call	subroutine_faf7
; 0xf993	c3	55	f8
	jp	do_SRESET
;
;
skip_f996:
	cp	0xee
	jr	nz,skip_f99e
; 0xf99a	cd	76	fb
	call	subroutine_fb76
; 0xf99d	e9
	jp	(hl)
;
;
skip_f99e:
	cp	0xe3
	jr	nz,skip_f9b7
; 0xf9a2	cd	76	fb
	call	subroutine_fb76
; 0xf9a5	e5
	push	hl
; 0xf9a6	cd	73	fb
	call	subroutine_fb73
; 0xf9a9	cd	a5	fb
	call	subroutine_fba5
; 0xf9ac	d1
	pop	de
; 0xf9ad	eb
	ex	de,hl
loop_f9ae:
	ld	a,(de)
; 0xf9af	be
	cp	(hl)
	call	nz,subroutine_fac7
; 0xf9b3	13
	inc	de
; 0xf9b4	23
	inc	hl
; 0xf9b5	18	f7
	jr	loop_f9ae
skip_f9b7:
	cp	0xce
	jr	nz,skip_fa0d
; 0xf9bb	21	dc	ff
	ld	hl,0xffdc
; 0xf9be	39
	add	hl,sp
; 0xf9bf	e5
	push	hl
; 0xf9c0	0e	00
	ld	c,0
;
loop_f9c2:
	ld	a,(KBF)
	or	a
	jr	z,loop_f9c2
	
; 0xf9c8	fe	1b
	cp	esc
	jr	z,skip_f9d4

; 0xf9cc	cd	7f	fb
	call	subroutine_fb7f
; 0xf9cf	77
	ld	(hl),a
; 0xf9d0	2b
	dec	hl
; 0xf9d1	0c
	inc	c
; 0xf9d2	18	ee
	jr	loop_f9c2
;
;
skip_f9d4:
	call	do_KEY2
; 0xf9d7	0c
	inc	c
	dec	c
	jp	z,do_SRESET
	
; 0xf9dc	cd	a5	fb
	call	subroutine_fba5
; 0xf9df	e1
	pop	hl
; 0xf9e0	d9
	exx
; 0xf9e1	21	00	00
	ld	hl,0
; 0xf9e4	01	00	00
	ld	bc,0
; 0xf9e7	d9
	exx
	
	
loop_f9e8:
	ld	b,c
; 0xf9e9	e5
	push	hl
; 0xf9ea	d1
	pop	de
; 0xf9eb	7e
	ld	a,(hl)
; 0xf9ec	d9
	exx



loop_f9ed:
	cpir
; 0xf9ef	e2	55	f8
	jp	po,do_SRESET
; 0xf9f2	20	f9
	jr	nz,loop_f9ed
; 0xf9f4	e5
	push	hl



loop_f9f5:
	exx
; 0xf9f6	1b
	dec	de
; 0xf9f7	1a
	ld	a,(de)
; 0xf9f8	10	0b
	djnz	skip_fa05


; 0xf9fa	d9
	exx
	pop	hl
	push	hl
	dec	hl
	call	subroutine_fac7


loop_fa01:
	pop	hl
; 0xfa02	d9
	exx
; 0xfa03	18	e3
	jr	loop_f9e8


skip_fa05:
	exx
; 0xfa06	ed	a1
	cpi
; 0xfa08	03
	inc	bc
	jr	nz,loop_fa01
	jr	loop_f9f5



skip_fa0d:
	cp	0xf4
; 0xfa0f	cc	ee	fa
	call	z,skip_faee
; 0xfa12	c3	55	f8
	jp	do_SRESET
;
;
;
Lfa15:
; 0xfa15	e5
	push	hl
; 0xfa16	21	06	00
	ld	hl,0x0006
; 0xfa19	f5
	push	af
; 0xfa1a	39
	add	hl,sp
; 0xfa1b	f1
	pop	af
; 0xfa1c	e3
	ex	(sp),hl
; 0xfa1d	08
	ex	af,af'
; 0xfa1e	f5
	push	af
; 0xfa1f	d9
	exx
; 0xfa20	c5
	push	bc
	push	de
	push	hl
; 0xfa23	d9
	exx
; 0xfa24	08
	ex	af,af'
; 0xfa25	f5
	push	af

	push	bc
	push	de
	push	hl

	push	iy
	push	ix

; 0xfa2d	06	10
	ld	b,0x10
; 0xfa2f	11	7a	ff
	ld	de,0xff7a

loop_fa32:
	call	subroutine_fba5

; 0xfa35	0e 03
	ld	c,3
loop_fa37:
	ld	a,(de)
; 0xfa38	13
	inc	de
; 0xfa39	cd	b5	fb
	call	subroutine_fbb5
; 0xfa3c	0d
	dec	c
	jr	nz,loop_fa37

; 0xfa3f	cd	9d	fb
	call	subroutine_fb9d
; 0xfa42	e1
	pop	hl
; 0xfa43	cd	53	fb
	call	subroutine_fb53
; 0xfa46	10	ea
	djnz	loop_fa32
; 0xfa48	c3	55	f8
	jp	do_SRESET




subroutine_fa4b:
	call	subroutine_fa66
	call	subroutine_fada

; 0xfa51	20	0d
	db	space, CR
; 0xfa53	20	52
	db	space
	db	"READY"
	db	space, space,space, null
	ret


subroutine_fa5e:
	call	subroutine_fada
; 0xfa61	1b
	dec	de
; 0xfa62	48
	ld	c,b
; 0xfa63	1b
	dec	de
; 0xfa64	4a
	ld	c,d
; 0xfa65	00
	nop


subroutine_fa66:
	ld	a,0xff
; 0xfa68	ed	47
	ld	i,a
; 0xfa6a	ed	5e
	im	2
	
SCITAB_pairs    equ (do_SETUP-SCITAB)/2

; 0xfa6c	3e	14
	ld	a, SCITAB_pairs  ; 0x14              ; size of table
; 0xfa6e	cd	b9	fa
	call	subroutine_fab9 ; outputs the following table to output ports
	

;
; code above does not return to fall into the table.
; The return address is incremented past it, to do_SETUP.
;



; 0Xfa71
	
SCITAB:
	
; Pairs of output_address, data.

; IDR  should be F0
; IMRB should be F6
; IMRA should be F7
; PVR  should be F8
; GPIP should be F1
; UCR  should be FC
; RSR  should be FD
; TSR  should be FE

; 0283
	db	PVR,DDR		; Set GPIP bit 1 as output
	db IDR, 002H
	db GPIP, 002H	; and set it high (Rx disabled)
	db PVR, TCDR	; set baud rate (Rx)
	db IDR, 002H
	db PVR, TDDR	; set baud rate (Tx)
	db IDR, 002H
	db PVR, TCDCR	; select prescale of four on both
	db IDR, 011H
	db UCR, 098H	; set 8-bit, 2 stop bits
	db RSR, 001H	; enable Rx
	db TSR, 001H	; enable Tx
	db PVR, AER
	db IDR, 0C0H	; rising edge for FDC ints
	db IMRA, 0C0H
	db IMRB, 001H
	db PVR, IERA
	db IDR, 0C0H
	db PVR, IERB+8	;  enable keyboard int
; 0xfa97	f0	01
	db IDR, 001H	; and set S bit
	

;	db 0x21, 0xE7, 0xFE
;	db 0x11, 0x40
; 02B0
;	db 0xFF, 0x01, 0x09, 0x00
;	db 0xED, 0xB0, 0x11, 0x00
;	db 0x00, 0x06, 0x10, 0xCD
;	db 0xB6, 0xFD, 0x56, 0xED
; 02C0
;	db 0x53, 0x00, 0x80, 0x23
;	db 0x1C, 0x10, 0xF7, 0xCD
;	db 0xBE, 0xFD, 0xC9, 0xE3
;	db 0xC5, 0x47, 0x4E, 0x23
; 02D0
;	db 0x7E, 0x23, 0xED, 0x79
;	db 0x10, 0xF8, 0xC1, 0xE3
;	db 0xC9, 0xCD, 0x53, 0xFB
;	db 0x3A, 0x47, 0xFF, 0xFE
; 02E0
;	db 0x5C, 0xD2, 0xA5, 0xFB
;	db 0xE6, 0x07, 0xC8, 0xCD
;	db 0xA0, 0xFB, 0x18, 0xF0


; 0xfa99

do_SETUP:
    ld  hl,INIT1
	ld	de,WINDOW
	ld	bc,9
	ldir
; 0xfaa4	11	00	00
	ld	de,0x0000
; 0xfaa7	06	10
	ld	b,0x10
; 0xfaa9	cd	b6	fd
	call	do_VDUON

loop_faac:
	ld	d,(hl)
; 0xfaad	ed	53	00	80
	ld	(0x8000),de
	

; 0xfab1	23
	inc	hl
; 0xfab2	1c
	inc	e
; 0xfab3	10	f7
	djnz	loop_faac
; 0xfab5	cd	be	fd
	call	do_VDUOFF
	ret



subroutine_fab9:     ; outputs the table after the following table to output ports

	ex	(sp),hl ; swap hl and top of stack
	push	bc  ; save


	ld	b,a     ; get byte count

loop_fabc:
	ld	c,(hl)  ; get the i/o address, put in register C
	inc	hl
; 0xfabe	7e
	ld	a,(hl)
	inc	hl
; 0xfac0	ed	79
	out	(c),a
	djnz	loop_fabc


	
; 0xfac4	c1
	pop	bc      ; restore
	ex	(sp),hl ; swap hl and top of stack
	ret


subroutine_fac7:
	call	subroutine_fb53
loop_faca:
	ld	a,(LPOS)
; 0xfacd	fe	5c
	cp	0x5c
	jp	nc,subroutine_fba5

; 0xfad2	e6	07
	and	7
	ret	z

; 0xfad5	cd	a0	fb
	call	subroutine_fba0
; 0xfad8	18	f0
	jr	loop_faca


subroutine_fada:
	ex	(sp),hl
; 0xfadb	7e
	ld	a,(hl)
; 0xfadc	23
	inc	hl
; 0xfadd	e3
	ex	(sp),hl
; 0xfade	b7
	or	a
; 0xfadf	c8
	ret	z
; 0xfae0	cd	60	fc
	call	do_VDUA
; 0xfae3	18	f5
	jr	subroutine_fada



subroutine_fae5:
	call	subroutine_fbb2
; 0xfae8	fe	60
	cp	0x60
	ret	c
; 0xfaeb	d6	20
	sub	0x20        ; make upper case?
	ret

skip_faee:
; 0xfaee	cd	76	fb
	call	subroutine_fb76
; 0xfaf1	22	78	ff
	ld	(variable_word_ff78),hl



subroutine_faf4:
	ld	hl,(variable_word_ff78)

subroutine_faf7:
	call	subroutine_fada
; 0xfafa	1b
	dec	de
; 0xfafb	48
	ld	c,b
; 0xfafc	00
	nop
; 0xfafd	0e	1f
	ld	c,0x1f

loop_faff:
	call	subroutine_fba5
	call	subroutine_fb38

loop_fb05:
	call	subroutine_fb5d
	inc	hl
	call	subroutine_fb12
	jr	nz,loop_fb05

; 0xfb0e	0d
	dec	c
; 0xfb0f	20	ee
	jr	nz,loop_faff
	ret


subroutine_fb12:
	call	subroutine_fba0 ; not do_VDUOFF
; 0xfb15	7d
	ld	a,l
; 0xfb16	e6	03
	and	0x03
; 0xfb18	cc	9d	fb
	call	z,subroutine_fb9d

; 0xfb1b	7d
	ld	a,l
; 0xfb1c	e6	0f
	and	0x0f
; 0xfb1e	c0
	ret	nz
	
; 0xfb1f	11	f0	ff
	ld	de,0xfff0
; 0xfb22	19
	add	hl,de
; 0xfb23	06	10
	ld	b,0x10

loop_fb25:
	ld	a,(hl)
; 0xfb26	23
	inc	hl
; 0xfb27	fe	20

	cp	space
	jr	c,skip_fb2f
	
; 0xfb2b	fe	7f
	cp	DEL
	jr	c,skip_fb31
	
skip_fb2f:
	ld	a,0x2e  ; '.' 

skip_fb31:
	call	subroutine_fbb5
; 0xfb34	10	ef
	djnz	loop_fb25
	
; 0xfb36	af
	xor	a
	ret


subroutine_fb38:
	call	subroutine_fb53
; 0xfb3b	c5
	push	bc
; 0xfb3c	cd	46	fb
	call	subroutine_fb46
; 0xfb3f	c4	a0	fb
	call	nz,subroutine_fba0  ; not do_VDUOFF
; 0xfb42	10	fb
	djnz	0xfb3f
; 0xfb44	c1
	pop	bc
	ret


subroutine_fb46:
	ld	a,l
; 0xfb47	e6	0f
	and	0x0f
	ret	z

; 0xfb4a	4f
	ld	c,a
	and	0x0c
	rrca
	add	a,c
	add	a,c
	add	a,c
	ld	b,a
	ret


subroutine_fb53:
	ld	a,h
; 0xfb54	cd	5e	fb
	call	subroutine_fb5e
; 0xfb57	7d
	ld	a,l
; 0xfb58	cd	5e	fb
	call	subroutine_fb5e
; 0xfb5b	18	43
	jr	subroutine_fba0



subroutine_fb5d:
	ld	a,(hl)
subroutine_fb5e:
	push	af
; 0xfb5f	07
	rlca
; 0xfb60	07
	rlca
; 0xfb61	07
	rlca
; 0xfb62	07
	rlca
; 0xfb63	cd	67	fb
	call	subroutine_fb67
; 0xfb66	f1

	pop	af
subroutine_fb67:
	and	0xf
	cp	10		; ten
	jr	c,skip_fb6f

	add	a,7		; hex A to ASCII A

skip_fb6f:
	add	a,'0'
	jr	subroutine_fbb5


subroutine_fb73:
	call	subroutine_fba0


subroutine_fb76:
	call	subroutine_fb82
; 0xfb79	67
	ld	h,a
; 0xfb7a	cd	82	fb
	call	subroutine_fb82
; 0xfb7d	6f
	ld	l,a
	ret


subroutine_fb7f:
	call	subroutine_fba0

subroutine_fb82:
	call	subroutine_fb91


subroutine_fb85:
	push	bc
; 0xfb86	07
	rlca
; 0xfb87	07
	rlca
; 0xfb88	07
	rlca
; 0xfb89	07
	rlca
; 0xfb8a	47
	ld	b,a
; 0xfb8b	cd	91	fb
	call	subroutine_fb91
; 0xfb8e	80
	add	a,b
; 0xfb8f	c1
	pop	bc
; 0xfb90	c9
	ret


subroutine_fb91:

	call	subroutine_fbb2

subroutine_fb94:
	cp	0x41
	jr	c,skip_fb9a

	add	a,9

skip_fb9a:
	and	0x0f
	ret


subroutine_fb9d:
	call	subroutine_fba0


subroutine_fba0:
	push	af
	ld	a,space
	jr	skip_fbad


subroutine_fba5:
	push	af
	ld	a,CR
	call	subroutine_fbb5

	ld	a,LF

skip_fbad:
	call	subroutine_fbb5
; 0xfbb0	f1
	pop	af
	ret


subroutine_fbb2:
	call	do_KEY1


subroutine_fbb5:
	call	do_VDUA
; 0xfbb8	f5
	push	af  ; save
	
	
; 0xfbb9	db	e0
	in	a,(port_0xe0)
	and	0x80            ; test bit 7 
	jr	nz,pop_af_and_return
	
	
; 0xfbbf	f1
	pop	af  ; restore
	
	
	
	
; 0xfbc0	f5
	push	af  ; save
; 0xfbc1	cd	ce	fe
	call	do_PRINT
	
	
	
pop_af_and_return:
	pop	af  ; restore

	ret


subroutine_fbc6:

	ex	(sp),hl

	push	de
	push	bc

	call	subroutine_fbd0

pop_bc_de_hl_and_return:
	pop	bc
	pop	de
	pop	hl
	ret


subroutine_fbd0:
	jp	(hl)

subroutine_fbd1:
; 0xfbd1	e3
	ex	(sp),hl
; 0xfbd2	d5
	push	de
	push	bc
;
	push	af
	call	subroutine_fbd0
	pop	af
;	
; 0xfbd9	18	f1
	jr	pop_bc_de_hl_and_return



do_KEY3:
	ld	a,(KBF)
	cp	0x1d    ; ascii GS Group separator
	ret	nz

; 0xfbe1	cd	34	fc
	call	do_KEY2
	jr	Lfc17


do_KEY1:
	push	hl
; 0xfbe7	2a	44	ff
	ld	hl,(CURSOR)
; 0xfbea	cd	b6	fd
	call	do_VDUON
; 0xfbed	cd	20	fd
	call	subroutine_fd20
; 0xfbf0	21	0a	68
	ld	hl,0x680a
	ld	(0x8000),hl
; 0xfbf6	cd	be	fd
	call	do_VDUOFF
loop_fbf9:
	call	do_KEY2
; 0xfbfc	28	fb
	jr	z,loop_fbf9
; 0xfbfe	cd	b6	fd
	call	do_VDUON
; 0xfc01	21	0a	08
	ld	hl,0x080a
	ld	(0x8000),hl
; 0xfc07	cd	be	fd
	call	do_VDUOFF
; 0xfc0a	e1
	pop	hl
; 0xfc0b	cd	11	fc
	call	subroutine_fc11
; 0xfc0e	28	d6

	jr	z,do_KEY1

	ret


subroutine_fc11:
	call	subroutine_fc25
; 0xfc14	fe	1d
	cp	0x1d
	ret	nz

Lfc17:
	ld	a,(SCNOW)
; 0xfc1a	b7
	or	a
; 0xfc1b	3e	00
	ld	a,0x00
; 0xfc1d	20	01
	jr	nz,skip_fc20

; 0xfc1f	3c
	inc	a

skip_fc20:
	ld	(SCNOW),a
; 0xfc23	af
	xor	a
	ret


subroutine_fc25:
	push	af

	ld	a,(SCNOW)
	or	a
; 0xfc2a	28	06
	jr	z,skip_fc32
; 0xfc2c	3a	42	ff
	ld	a,(SCMAX)
	ld	(SCNOW),a
skip_fc32:

	pop	af
	ret

do_KEY2:
	ld	a,(KBF) ; if key is zero, return
	or	a
	ret	z

; else clear keyboard buffer

; 0xfc39	e5
	push	hl
	push	de
	push	bc
;
; 0xfc3c	21	4f	ff
	ld	hl,KBF+1    ; 0xff4f

; 0xfc3f	e5
	push	hl
; 0xfc40	d1
	pop	de
	dec	de
; 0xfc42	1a
	ld	a,(de)

	ld	bc,15   ; size of buffer
	ldir        ; do bc times
; 0xfc48	c1
;
;
	pop	bc
	pop	de
	pop	hl
	ret


do_KEY4:
	ld	a,(KBF)
	or	a
	ret	z

; 0xfc51	3e	ff
	ld	a,0xff
; 0xfc53	c9
	ret


do_TIME:
	push	af


loop_fc55:
	ld	a,0x6f
loop_fc57:
	ex	(sp),hl
; 0xfc58	e3
	ex	(sp),hl
; 0xfc59	3d
	dec	a
; 0xfc5a	20	fb
	jr	nz,loop_fc57
; 0xfc5c	10	f7
	djnz	loop_fc55
; 0xfc5e	f1
	pop	af
	ret
;
;
do_VDUA:
	call	subroutine_fbd1
; 0xfc63	cd	b6	fd
	call	do_VDUON
; 0xfc66	01	be	fd
	ld	bc,0xfdbe
; 0xfc69	c5
	push	bc
; 0xfc6a	21	f1	fc
	ld	hl,variable_byte_fcf1
; 0xfc6d	34
	inc	(hl)
; 0xfc6e	35
	dec	(hl)
; 0xfc6f	20	08
	jr	nz,skip_fc79
; 0xfc71	fe	1b
	cp	esc
	jp	nz,skip_fcf4
; 0xfc76	cb	fe
	set	7,(hl)
	ret
;
;
skip_fc79:
	bit	7,(hl)
; 0xfc7b	28	4a
	jr	z,skip_fcc7
; 0xfc7d	36	00
	ld	(hl),0x00
; 0xfc7f	32	f2	fc
	ld	(variable_byte_fcf2),a
; 0xfc82	fe	48
	cp	0x48
	jr	nz,skip_fc8f
; 0xfc86	cd	25	fc
	call	subroutine_fc25
; 0xfc89	af
	xor	a
; 0xfc8a	2a	40	ff
	ld	hl,(WINDOW)
; 0xfc8d	18	60
	jr	0xfcef
;
;
skip_fc8f:
	cp	0x4a
	jr	nz,skip_fc9f
; 0xfc93	2a	44	ff
	ld	hl,(CURSOR)
; 0xfc96	3e	a0
	ld	a,0xa0
loop_fc98:
	ld	(hl),space
; 0xfc9a	23
	inc	hl
; 0xfc9b	bc
	cp	h
	jr	nz,loop_fc98
	ret
;
;
skip_fc9f:
	cp	0x4b
	jr	nz,skip_fcb4
; 0xfca3	2a	44	ff
	ld	hl,(CURSOR)
; 0xfca6	3a	47	ff
	ld	a,(LPOS)
subroutine_fca9:
	sub	0x60
	jr	nc,subroutine_fca9
loop_fcad:
	ld	(hl),space
; 0xfcaf	23
	inc	hl
; 0xfcb0	3c
	inc	a
; 0xfcb1	20	fa
	jr	nz,loop_fcad
	ret


skip_fcb4:
	cp	0x59
	jr	nz,skip_fcbb
; 0xfcb8	36	02
	ld	(hl),0x02
	ret


skip_fcbb:
	cp	0x46
	jr	0xfcc3

;
skip_fcbf:
	cp	0x47
	jr	nz,skip_fcc7
; 0xfcc3	32	f3	fc
	ld	(variable_byte_fcf3),a
; 0xfcc6	c9
	ret
;
;
skip_fcc7:
	sub	space
; 0xfcc9	4f
	ld	c,a
; 0xfcca	3a	f2	fc
	ld	a,(variable_byte_fcf2)
; 0xfccd	fe	59
	cp	0x59
	ret	nz
; 0xfcd0	35
	dec	(hl)
; 0xfcd1	28	12
	jr	z,skip_fce5
; 0xfcd3	79
	ld	a,c
; 0xfcd4	fe	20
	cp	space
	ret	nc
; 0xfcd7	af
	xor	a
; 0xfcd8	2a	40	ff
	ld	hl,(WINDOW)
; 0xfcdb	11	60	00
	ld	de,0x0060
; 0xfcde	0c
	inc	c
; 0xfcdf	0d
	dec	c
	jr	z,skip_fcef
; 0xfce2	19
	add	hl,de
; 0xfce3	18	fa
	jr	0xfcdf
skip_fce5:
	ld	a,c
; 0xfce6	fe	60
	cp	0x60
	ret	nc
	
	
; 0xfce9	06	00
	ld	b,0x00
; 0xfceb	2a	44	ff
	ld	hl,(CURSOR)
; 0xfcee	09
	add	hl,bc
skip_fcef:
	jr	0xfd1a
	
	
	
	
	
variable_byte_fcf1:
    db  00
variable_byte_fcf2:
    db  00
variable_byte_fcf3:
    db  0x47
    
    
    
skip_fcf4:
	ld	hl,($FF44)  ; 2A 44 ff

; 0xfcf7	fe	7f
	cp	DEL
	jr	nz,skip_fd04
; 0xfcfb	36	20
	ld	(hl),space

loop_fcfd:
	dec	hl
; 0xfcfe	3a	47	ff
	ld	a,(LPOS)
; 0xfd01	3d
	dec	a
; 0xfd02	18	16
	jr	0xfd1a
;
;
skip_fd04:
	cp	space
	jr	c,skip_fd2c
; 0xfd08	cd	8e	fd
	call	subroutine_fd8e
; 0xfd0b	77
	ld	(hl),a
; 0xfd0c	3a	f3	fc

	ld	a,(variable_byte_fcf3)
	cp	0x46
	jr	nz,skip_fd15

	set	7,(hl)

skip_fd15:
	inc	hl
; 0xfd16	3a	47	ff
	ld	a,(LPOS)
; 0xfd19	3c
	inc	a
; 0xfd1a	32	47	ff
	ld	(LPOS),a
; 0xfd1d	22	44	ff
	ld	(CURSOR),hl

subroutine_fd20:
	ld	a,l
; 0xfd21	2e	0e
	ld	l,0x0e
; 0xfd23	22	00	80
	ld	(0x8000),hl
; 0xfd26	2c
	inc	l
; 0xfd27	67
	ld	h,a
; 0xfd28	22	00	80
	ld	(0x8000),hl
; 0xfd2b	c9
	ret


skip_fd2c:
	cp	BS
	jr	z,loop_fcfd
; 0xfd30	fe	0d
	cp	CR
	jr	nz,skip_fd42
; 0xfd34	3a	47	ff
	ld	a,(LPOS)
; 0xfd37	a7
	and	a
; 0xfd38	c8
	ret	z
; 0xfd39	cd	a9	fc
	call	subroutine_fca9
; 0xfd3c	11	a0	ff
	ld	de,0xffa0
; 0xfd3f	19
	add	hl,de
; 0xfd40	18	d8
	jr	0xfd1a


skip_fd42:
	cp	BEL
	jr	nz,skip_fd57
; 0xfd46	0e	00
	ld	c,0
; 0xfd48	3a	49	ff
	ld	a,(CURDRV)

loop_fd4b:
	xor	0x02
; 0xfd4d	d3	e0
	out	(port_0xe0),a
; 0xfd4f	06	c0
	ld	b,0xc0

loop_fd51:
	djnz	loop_fd51

; 0xfd53	0d
	dec	c
	jr	nz,loop_fd4b
;
	ret


skip_fd57:
	cp	FF
jr	z,skip_fd5e
; 0xfd5b	fe	0a
	cp	LF
	ret	nz
skip_fd5e:
	ld	a,(SCNOW)
; 0xfd61	b7
	or	a
	jr	z,skip_fd6a
; 0xfd64	3d
	dec	a
	jr	z,skip_fd73
; 0xfd67	32	43	ff
	ld	(SCNOW),a
skip_fd6a:
	ld	de,0x0060
; 0xfd6d	19
	add	hl,de
; 0xfd6e	cd	8e	fd
	call	subroutine_fd8e
; 0xfd71	18	aa
	jr	0xfd1d
skip_fd73:
	ld	de,0x400a
; 0xfd76	ed	53	00	80
	ld	(0x8000),de

loop_fd7a:
	call	do_KEY4
; 0xfd7d	28	fb
	jr	z,loop_fd7a
; 0xfd7f	11	0a	08
	ld	de,0x080a
; 0xfd82	ed	53	00	80
	ld	(0x8000),de
; 0xfd86	cd	34	fc
	call	do_KEY2
; 0xfd89	cd	11	fc
	call	subroutine_fc11
; 0xfd8c	18	dc
	jr	0xfd6a
subroutine_fd8e:
	push	af
; 0xfd8f	7c
	ld	a,h
; 0xfd90	fe	a0
	cp	0xa0
	jr	c,skip_fdb4
; 0xfd94	2a	40	ff
	ld	hl,(WINDOW)
; 0xfd97	c5
	push	bc
; 0xfd98	e5
	push	hl
; 0xfd99	11	60	00
	ld	de,0x0060
; 0xfd9c	19
	add	hl,de
; 0xfd9d	e5
	push	hl
; 0xfd9e	d1
	pop	de
; 0xfd9f	21	00	a0
	ld	hl,0xa000
; 0xfda2	a7
	and	a
; 0xfda3	ed	52
	sbc	hl,de
; 0xfda5	e5
	push	hl
; 0xfda6	c1
	pop	bc
; 0xfda7	e1
	pop	hl
; 0xfda8	eb
	ex	de,hl
; 0xfda9	ed	b0
	ldir
; 0xfdab	eb
	ex	de,hl
; 0xfdac	c1
	pop	bc
; 0xfdad	e5
	push	hl
loop_fdae:
	ld	(hl),space
; 0xfdb0	2c
	inc	l
subroutine_fdb1:
	jr	nz,loop_fdae
; 0xfdb3	e1
	pop	hl

skip_fdb4:
	pop	af
	ret


do_VDUON:
	push	af
	ld	a,(CURDRV)
	or	0x04
	jr	0xfdc4


do_VDUOFF:
	push	af
	ld	a,(CURDRV)
	and	0xfb


; 0xfdc4	d3	e0
	out	(port_0xe0),a
; 0xfdc6	32	49	ff
	ld	(CURDRV),a
; 0xfdc9	f1
	pop	af
; 0xfdca	c9
	ret


do_PSCROL:
	push	hl
	push	de
; 0xfdcd	32	42	ff
	ld	(SCMAX),a
; 0xfdd0	21	00	a0
	ld	hl,0xa000
	ld	de,0xffa0
	add	hl,de
; 0xfdd7	3d
	dec	a
	jr	nz,0xfdd6	; duff jump ???

; 0xfdda	22	40	ff
	ld	(WINDOW),hl
; 0xfddd	d1
	pop	de
	pop	hl
	ret


do_PARIN:
	in	a,(port_0xe8)
	ret


do_PAROUT:
	out	(port_0xe8),a
	ret


do_RESDSK:
	call	subroutine_fbc6
	call	subroutine_fe28
	ld	(CURDRV),a
	out	(port_0xe0),a
	ld	a,(STEP)
; 0xfdf4	e6	0f
	and	0x0f
; 0xfdf6	cd	7d	fe
	call	subroutine_fe7d
; 0xfdf9	e6	10
	and	0x10
; 0xfdfb	c9
	ret


do_RDDSK:
	call	subroutine_fbc6
; 0xfdff	11	84	fe
	ld	de,0xfe84


subroutine_fe02:
	call	subroutine_fe36
; 0xfe05	3e	80
	ld	a,0x80
; 0xfe07	cd	7b	fe
	call	subroutine_fe7b
; 0xfe0a	e6	1c
	and	0x1c
	ret


do_WRDSK:
	call	subroutine_fbc6
; 0xfe10	11	8a	fe
	ld	de,0xfe8a
	call	subroutine_fe36
; 0xfe16	3e	a0
	ld	a,0xa0
	call	subroutine_fe7b
; 0xfe1b	e6	7c
	and	0x7c
	ret	nz
; 0xfe1e	11	90	fe
	ld	de,0xfe90
	call	subroutine_fe02
; 0xfe24	c8
    ret z
; 0xfe25	f6  02
	or	2
	ret


subroutine_fe28:
	ld	a,(ix+0)
; 0xfe2b	e6	03
	and	0x03
; 0xfe2d	4f
	ld	c,a
; 0xfe2e	06	00
	ld	b,0x00
; 0xfe30	21	4a	ff
	ld	hl,DRVTAB
; 0xfe33	09
	add	hl,bc
; 0xfe34	7e
	ld	a,(hl)
; 0xfe35	c9
	ret


subroutine_fe36:
	call	subroutine_fe28
; 0xfe39	47
	ld	b,a
; 0xfe3a	21	49	ff
	ld	hl,CURDRV
; 0xfe3d	ae
	xor	(hl)
; 0xfe3e	e6	f0
	and	0xf0
; 0xfe40	f5
	push	af
; 0xfe41	7e
	ld	a,(hl)
; 0xfe42	e6	0e
	and	0x0e
; 0xfe44	b0
	or	b
; 0xfe45	77
	ld	(hl),a
; 0xfe46	d3	e0
	out	(port_0xe0),a
; 0xfe48	f1
	pop	af
	
    if  making_original_buggy_version
	
; 0xfe49	c4	6b	fe
	call	nz,call_fe6b
; 0xfe4c	dd	46	01
	ld	b,(ix+1)
; 0xfe4f	db	e5
	in	a,(port_0xe5)
	
	else
; 0xfe49	db	e5	
	in	a,(port_0xe5)
; 0xfe4b	c4	6b	fe
	call	nz,call_fe6b
; 0xfe4e	dd	46	01
	ld	b,(ix+1)
	
	endif
	
; 0xfe51	b8
	cp	b
; 0xfe52	78
	ld	a,b
; 0xfe53	d3	e7
	out	(port_0xe7),a
; 0xfe55	3a	48	ff
	ld	a,(STEP)
; 0xfe58	c4	7d	fe
	call	nz,subroutine_fe7d
; 0xfe5b	dd	7e	02
	ld	a,(ix+2)
; 0xfe5e	d3	e6
	out	(port_0xe6),a
; 0xfe60	dd	6e	03
	ld	l,(ix+3)
; 0xfe63	dd	66	04
	ld	h,(ix+4)
; 0xfe66	ed	53	1e	ff
	ld	(0xff1e),de
; 0xfe6a	c9
	ret


call_fe6b:
	ld	hl,0xfe90
; 0xfe6e	22	1e	ff
	ld	(0xff1e),hl
; 0xfe71	3e	c0
	ld	a,0xc0
; 0xfe73	cd	7d	fe
	call	subroutine_fe7d
; 0xfe76	db	e6
	in	a,(port_0xe6)
; 0xfe78	d3	e5
	out	(port_0xe5),a
; 0xfe7a	c9
	ret


subroutine_fe7b:
	ld	c,0xe7
subroutine_fe7d:
	out	(port_0xe4),a
; 0xfe7f	37
	scf

; 0xfe80	da	80	fe
	jp	c,0xfe80        ; loop forever?
; 0xfe83	c9
	ret


; 0xfe84	ed	a2
	ini
; 0xfe86	37
	scf
; 0xfe87	fb
	ei
; 0xfe88	ed	4d
	reti
; 0xfe8a	ed	a3
	outi
; 0xfe8c	37
	scf
; 0xfe8d	fb
	ei
; 0xfe8e	ed	4d
	reti
; 0xfe90	db	e7
	in	a,(port_0xe7)
; 0xfe92	37
	scf
; 0xfe93	fb
	ei
; 0xfe94	ed	4d
	reti
	
INTRQ:
; 0xfe96	db	e4
	in	a,(port_0xe4)
	or	a
	ei
	reti



do_STEPR:
	ld	(STEP),a
	ret

Lfea0:
; 0xfea0	f5
	push	af
; 0xfea1	db	e0
	in	a,(port_0xe0)
; 0xfea3	e6	7f
	and	DEL
	jr	nz,skip_feb2
; 0xfea7	3e	d0
	ld	a,0xd0
; 0xfea9	d3	e4
	out	(port_0xe4),a
	
; 0xfeab	f1
	pop	af
; 0xfeac	21	3d	f8
	ld	hl,do_HRESET
; 0xfeaf	e3
	ex	(sp),hl
; 0xfeb0	18	19
	jr	skip_fecb


skip_feb2:
	push	hl
	push	bc
; 0xfeb4	21	4d	ff
	ld	hl,0xff4d
; 0xfeb7	4f
	ld	c,a
; 0xfeb8	06	0f
	ld	b,0x0f
; 0xfeba	af
	xor	a
	
loop_febb:
	inc	hl
; 0xfebc	be
	cp	(hl)
; 0xfebd	28	08
	jr	z,0xfec7    ; duff jump?
; 0xfebf	10	fa
	djnz	loop_febb

; 0xfec1	3e	07
	ld	a,BEL
; 0xfec3	cd	60	fc
	call	do_VDUA
; 0xfec6	fe	71
	cp	0x71
; 0xfec8	c1
	pop	bc
	pop	hl
	pop	af
skip_fecb:
	ei
	reti

; 0xfece

do_PRINT:
	push	af ; save register and flags


PRINT1:
;;	in	a,(port_0xf1)
	in	a,(GPIP) ; wait for handshake ready
	bit	2,a
	jr	nz,PRINT1


PRINT2:
;;	in	a,(port_0xfe)
	in	a,(TSR) ; wait for UART ready
	bit	7,a
	jr	z,PRINT2

; 0xfedb	f1
	pop	af
;;	out	(port_0xff),a
	out	(UDR),a ; output byte
	ret


; 0xfedf	00
	nop
; 0xfee0	00
	nop
; 0xfee1	00
	nop
; 0xfee2	00
	nop
; 0xfee3	00
	nop
; 0xfee4	00
	nop
; 0xfee5	00
	nop
; 0xfee6	00
	nop
	
	
INIT1:
; 0xfee7	00	94
	defw    VDU1 ; default 
; 0xfee9	20	20

	defb    FRAME,FRAME ; default 
; 0xfeeb	00	94
	defw    VDU1 ; default cursor position
; 0xfeed	00
	defb    000H ; dummy
; 0xfeee	00
	defb    000H ; default line position
; 0xfeef	1b
	defb    01BH ; default step rate (slowest)
	;
	;
	;
CRTC:
; 0xfef0
	defb    07FH
; 0xfef1
	defb    LINE
; 0xfef2
	defb    68H
; 0xfef3
	defb    38H
	defb    21H
; 0xfef5
	defb    07H
; 0xfef6
	defb    FRAME
	defb    FRAME

; 0xfef8
	defb	50H
; 0xfef9
	defb	08H
; 0xfefa
	defb	08H
; 0xfefb
	defb	08H
; 0xfefc
	defb	14H
; 0xfefd
	defb	00H
; 0xfefe
	defb	00H
; 0xfeff
	defb	00H

SIIVEC:
; 0xff00
	defW	Lfea0
; 0xff02
	defw	0000H
; 0xff04
	defw	0000H
; 0xff06
	defw	0000H
; 0xff08
	defw	0000H
; 0xff0a
	defw	0000H
; 0xff0c
	defw	0000H
; 0xff0e
	defw	0000H
; 0xff10
	defw	0000H
; 0xff12
	defw	0000H
; 0xff14
	defw	0000H
; 0xff16
	defw	0000H
; 0xff18
	defw	0000H
; 0xff1a
	defw	0000H
; 0xff1c	96 FE

	defw	INTRQ   ; FE96
; 0xff1e
	defw	0000H
	
; 0xff20
;;	DS  020H ; reserved for expansion
; 
	DB  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
	DB  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ; reserved for expansion

; 0xff40
WINDOW:	defw	0000H ; VDU start address

; 0xff42
SCMAX:	defb	00H ; scroll limit

; 0xff43
SCNOW:	defb	00H ; lines scrolled / scroll flag

; 0xff44
CURSOR:	defw	0000H ; cursor position

; 0xff46
KEYBUF:	defb	00H ; 

; 0xff47
LPOS:	defb	00 ; line position (00-5FH)

; 0xff48
STEP:	defb	00 ; disc stepper rate

; 0xff49
CURDRV	defb	00 ; image of control port

; 0xff4a
DRVTAB:
	defb	$10
	defb	$20
	defb	$11
	defb	$21
;
;
; 0xff4e
KBF:
;;  DS  010H ; keyboard buffer
	DB  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ; keyboard buffer


Lff5e:
    .dw do_SRESET


; 0xff60
    defw	0000H
; 0xff62
    defw	0000H
; 0xff64
    defw	0000H
; 0xff66
    defw	0000H
; 0xff68
    defw	0000H
; 0xff6a
    defw	0000H
; 0xff6c
    defw  Lfa15

; 0xff6e	00	00
SDEN:
	defb	00H
	defb	00H 
	
; 0xff70
	defb	01H
	defw	0080H

Lff73:
	defb    00H
; 0xff74
	defb	00H
; 0xff75
	defb	01
	defw	0f600H
	
	
	
variable_word_ff78:
    defw	0000H
;
; register name strings
;
; 0xff7a	49 58 20 49
	db	"IX IY "
	db	"HL DE "
	db	"BC AF "
	db	"HL'DE'"
	db	"BC'AF'"
	db	"SP AT "
	db	"S  "
	db	"S  "
	db	"S  "
	db	"S  "
; 0xffaa	ff  blank EPROM values.
	db 0xff
	db 0xff
	db 0xff
; 0xffad	ff
	db 0xff
	
;
; The ROM data from the newsletter OCR ends here.
; However I shall assume the rest of the boot ROM is blank.
; 
;

; 07C0
	db 0xFF, 0xFF, 0xFF, 0xFF
	db 0xFF, 0xFF, 0xFF, 0xFF
	db 0xFF, 0xFF, 0xFF, 0xFF
	db 0xFF, 0xFF, 0xFF, 0xFF

; 07D0
	db 0xFF, 0xFF, 0xFF, 0xFF
	db 0xFF, 0xFF, 0xFF, 0xFF
	db 0xFF, 0xFF, 0xFF, 0xFF
	db 0xFF, 0xFF, 0xFF, 0xFF

; 07E0
	db 0xFF, 0xFF, 0xFF, 0xFF
	db 0xFF, 0xFF, 0xFF, 0xFF
	db 0xFF, 0xFF, 0xFF, 0xFF
	db 0xFF, 0xFF, 0xFF, 0xFF

; 07F0
	db 0xFF, 0xFF, 0xFF, 0xFF
	db 0xFF, 0xFF, 0xFF, 0xFF
; 07F8
	db 0xFF, 0xFF, 0xFF, 0xFF
	db 0xFF, 0xFF, 0xFF, 0xFF
    .end