;:sys36864
	;.opt oo
vic	= 53248
control	= vic+17
frame	= vic+32
irqvek	= $314
key	= 203
oldirq	= $ea31
strout	= $ab1e
flag	= 181
ctr1	= 247
ctr2	= ctr1+1
none	= 64
mem	= 249
time	= 14
	*= 51200
	jmp init
text	.byte "\x93\x11   **** commodore 64 screen tool ****"
	.byt 13 
	 .byte " \x11<c> by nig software service nss 250186"
	.byt 13,0
init	sei
	lda #<irqnew
	ldy #>irqnew
	sta irqvek
	sty irqvek+1
	cli
	lda #0
	sta flag 
	 sta ctr1 
	 sta ctr2
	lda #<text
	ldy #>text
	jmp strout
irqnew	jsr blank
	jmp oldirq
blank	lda flag 
	 beq nochan
	lda key 
	 cmp #none
	beq back
	lda control 
	 ora #16
	sta control 
	 lda mem
	sta frame 
	 lda #0
	sta ctr1 
	 sta ctr2
	sta flag
back	rts
nochan	lda key 
	 cmp #none
	beq nopress
	lda #0 
	 sta ctr1 
	 sta ctr2
nopress	inc ctr1 
	 bne noinc
	inc ctr2
noinc	lda ctr2 
	 cmp #time
	bcc back
	lda #255 
	 sta flag
	lda control 
	 and #239
	sta control 
	 lda frame
	sta mem 
	 lda #0 
	 sta frame
	rts