[Coco] Detecting CoCo 1 versus CoCo 2

[Sean Conner]

It was thus said that the Great Juan Castro via Coco once stated:
> > From Darren Atkison:
> > The audio MUX on the CoCo 1 is bi-directional, but the integrated
> > DAC/MUX on the CoCo 2 is uni-directional. There is a test you can do
> > where you toggle the single-bit sound output and check to see if the
> > cassette input level changes to match. If it does change then it's a
> > CoCo 1.
> 
> Oh man, if anybody here has that code I'd like to see it.

  If I understand the explanation right, then something like:

	lda	$FF22
	ora	#2
	sta	$FF22		; enable single bit output
	lda	$FF20
	bita	#1		; check cassette data input
	beq	coco2		; if not 1, then CoCo2

would work.  In BASIC, this would be:

	10 A = PEEK&HFF22
	20 A = A OR 2
	30 POKE&HFF22,A
	40 A = PEEK&HFF20
	50 A = A AND 1
	60 IF A == 0 THEN PRINT "COCO2"

  -spc