I think I may have found a way to detect a CoCo1 vs a CoCo2. At least it
worked in the very limited test of the two machines I have. Rather than
look for the SALT chip it tries to detect if the machine has the custom
integrated DAC chip.
The theory is that the custom chip in the CoCo 2 does not allow
bidirectional flow through the analog switch, whereas the MC14529B used in
the CoCo 1 does. The test selects the cassette port as the audio source
and then toggles the single-bit sound output while looking for a change on
the cassette data input. If the predicted change is seen then it would
appear that bidirectional flow through the switch is occuring and the
machine is a CoCo 1.
Should anyone care to try it and report their findings, below is the Basic
program I used to perform the test:
10 POKE &HFF23,&H33
20 POKE &HFF22,&HFA
30 POKE &HFF23,&H37
40 AUDIO ON
50 POKE &HFF22,0
60 A=PEEK(&HFF20) AND 1
70 POKE &HFF22,2
80 B=PEEK(&HFF20) AND 1
90 AUDIO OFF
100 PRINT "THIS APPEARS TO BE A COCO";(A<>B)+2
Darren
CoCo 1 vs 2 detection by Darren A.
CoCo 1 vs 2 detection by Darren A.
The following text was copied from the CoCo mailing list.