VIC-20 RS-232 bug

From: Professor Dredd (
Date: 2001-06-01 05:01:18

Hiya Anders,

--- "Carlsson, Anders" <> wrote:
> Also, there might be ROM bugs on the VIC-20 when
> dealing with RS-232
> communication. I have an early issue of a Swedish

My understanding is that the bug occurs in the RS-232
OPEN routine of the VIC KERNAL. Seems it checks the
wrong VIA registers for "Data Set Ready" and "Clear to
Send". The code in question occurs at $F512 and $EFF4.
The bug was corrected on the C-64.


> If anyone wants to know more about this subject, I
> can bring the paper
> some other day and translate the letter.

Of course  :)

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