CBM 8050 programming problems

From: Marko Mäkelä (msmakela_at_cc.hut.fi)
Date: 2001-12-31 08:39:37

Hi all,

Yesterday I made some progress with cbmlink and finally got the cassette
port based disk copying to work on several Commodores.  The Vic-20 was the
most difficult environment, since its timer interrupt affects the cassette
write line.  As a solution, I disabled the timer interrupts.

Some problems remained with the PET and PET-II versions.  First, the PET
question: copying disks in unit 0 works fine, but unit 1 fails.  I even
tried this from BASIC:

	PRINT#15,"U1:2 0 1 0":REM works fine
	PRINT#15,"U1:2 1 1 0":REM ?DS$ gives "70,NO CHANNEL,00,00"

By doing a GET#2,A$ right after the OPEN2,8,2, I verified that the
allocated channel was 11.  I tried also other channels, e.g.
OPEN2,8,2,"#4", but it didn't matter.  Is this perhaps a 8050 bug?
I didn't try this on my 8250 yet.

On the B-256 (CBM 720) I had another problem: when my machine language
program does the equivalent of OPEN15,8,15,"UI":INPUT#15,A,A$,B,C:CLOSE15,
everything works fine.  But when I try it with an empty file name, I keep
getting status 128 (device not present).  Any suggestions?

BTW, now there is some more information about the C2N232 device available:

Happy new year!


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