conout	equ	02h		;character out
boot	equ	0		;Restart
bdos	equ	05		;entry point
passes	equ	08		;# of passes to run
acr	equ	0dh		;carriage return
alf	equ	0ah		;line feed
passcnt	equ	1
port	equ	4

;***************************************************************
;*
;*  This program tests switchboard ports by executing OUT
;*  instructions followed by IN instructions and comparing
;*  data.
;*
;***************************************************************

	org	100h

start	lxi	sp,stack
	call	errmsg		;Prints error bit pattern
	jmp	boot

errmsg	lxi	d,msg3
	call	pbuff
	call	bitout
	lxi	d,msg4
	call	pbuff
	call	bitout
	ret

bitout	mvi	b,8		;bit counter
bitlp	push	b
	rlc			;first bit
	jc	one		;if on
	mvi	c,conout
	mvi	e,'0'		;if off
	call	bdos		;Print character
	pop	b
	dcr	b		;decrement bit counter
	push	b
	jnz	bitlp		;next bit
	pop	b
	ret
one	mvi	e,'1'		;on bit
	mvi	c,conout
	call	bdos		;Print character
	pop	b
	dcr	b		;decrement bit counter
	push	b
	jnz	bitlp		;next bit
	pop	b
	ret

pbuff	mvi	c,9
	jmp	bdos
rbuff	mvi	c,10
	jmp	bdos
msg3	db			acr,alf
	db			'Pass '
	db			passcnt
	db			' Port '
	db			port
	db			' should be $'

msg4	db			' was $',acr,alf
error	ds			1
testpat	db			0
	db			0aah
	db			55h
	db			0cch
	db			66h
	db			33h
	db			99h
	db			0ffh

	ds	30
stack	equ	$
	end