lda $d0b8	; check SCPU speed
	sta scpu_turbo	; store
	lda #00
	sta $d07a	; slow down SCPU to 1MHz
	sta $de00	; switch to Z80
	nop		; req'd for switch back
here:	lda #00		; $00 value stays if CPU switches not
	sta cpm_present	; CP/M availability 0 = not / 1 = yes
	ldx scpu_turbo	; get stored SCPU speed
	cpx #01		
	bne skip	; if was 1MHz skip rest
	dex
	stx $d07b	; restore 20MHz SCPU speed
skip:	rts
		
cpm_present: 
.byte $00

scpu_turbo:
.byte $00

ORG $0000		; start address req'd but $0000 see Z80 as $0000 and 6502 as $1000
	nop
	ld a, $01
	ld (here+1), a	; stores CP/M availability - substract $1000 from here+1
	ld ($CE00), a	; switches back to 6502
	nop
	jp $0000