;APRIL 11, 1986
;BY RONALD E. JACOBS
;THIS PROGRAM READS THE MPZ80 SWITCHES 1-6 AND /PINT
;TYPE ANY KEY TO EXIT

	.z80

	jp	1000h

	org	0EFDh
	halt
	halt

	call	curoff		;turn off the cursor
	call	uinit		;select serial port 1
repeat:	ld	a,(402h)
	push	af
	call	lbyte
	call	conv
	call	cout
	pop	af
	call	conv
	call	cout
	call	spacer
	call	binary
	call	bs		;backspace ten spaces
	call	done		;see if to warm boot because character at kbd
	jp	repeat

LBYTE:	RRCA
	RRCA
	RRCA
	RRCA
	ret

CONV:	AND	00fh
	ADD	A,090H
	DAA
	ADC	A,040H
	DAA
	LD	C,A
	ret

	base	equ	48h
	group1	equ	1
	grpctl	equ	4Fh
	lsr	equ	base+5
	thre	equ	20h
	thr	equ	base
	dr	equ	1		;data ready in receiver buffer reg.
	rbr	equ	base

uinit:	ld	a,group1
	out   	(grpctl),a		;set up for UART 1
	ret

done:	in	a,(lsr)		;get uart status
	and	dr		;character typed at terminal?
	ret	z	
	in	a,(rbr)		;clear the buffer by reading it

	ld	c,1bh		;ascii escape sequence to turn cursor back on
	call	cout
	ld	c,'.'		;ascii .
	call	cout
	ld	c,'0'		;ascii 0
	call	cout

	ld	hl,0000		;program counter <-- 0000 for task 1
	ld	(0015h),hl
	jp	0815h		;restore task 1 (warm boot)

cout:	in	a,(lsr)			;get uart status
	and	thre
	jr	z,cout			;loop until tbe
	ld	a,c
	out	(thr),a			;output the data to uart
	ret

	;
	;backspace a number of spaces
	;

bs:	ld	b,12d		;count of # of backspaces
bs1:	ld	c,08		;ascii backspace
	call	cout
	dec	b		;decrement count
	jp	nz,bs1
	ret

curoff:	ld	c,1bh		;ascii escape
	call	cout
	ld	c,'.'		;ascii .
	call	cout
	ld	c,'1'		;ascii 1
	call	cout
	ret

binary:	ld	a,(402h)	;cpu switch port
	ld	b,8		;8 bits count
nxtbit:	rlca
	ld	h,a		;save the a register
	and	00000001b	;mask all but lowest bit
	cp	1		;is the bit a 1 ?
	ld	c,'0'
	jp	nz,putbit	;put a '1' to the terminal
	ld	c,'1'
putbit:	call	cout		;put a '0' to the terminal 
	ld	a,h		;retrieve the a register
	deã	â		;alì ¸ digitó done?
	ret	z
	jp	nxtbit		;do next binary digit

spacer:	call	space1		;print two spaces
space1:	ld	c,' '		;prepare to print a space
	call	cout
	ret

	end