Dummy read after disk access necessary at RS-232 access

From: Christian Johansson (c64_at_comhem.se)
Date: 2004-02-07 23:27:31

I have written a C128 program that does both RS-232 accesses and disk drive
accesses. I know that it is not possible to do these accesses at the same
time so I do them after each other. However, one thing I have noticed is
that every time I have read data from or written data to the disk drive I
have to do a dummy read from the RS-232 channel even if there is no data in
the RS-232 input buffer (GET#1,A$ when programming in BASIC if channel 1 is
the RS-232 channel). If I don't do this, the RS-232 channel gets messed up.
I don't remember what happened right now if I didn't do it but I think that
all bytes received on the RS-232 channel after the disk drive access had the
wrong values if I didn't do the dummy read. I'm just curious to know if
anybody knows why the dummy reads are necessary?

/Christian Johansson

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