Re: VIC-20 RS-232 ROM Routines (was: VIC-1011A)

From: Professor Dredd (
Date: 2001-06-01 20:20:14

Hiya Anders, 

--- "Carlsson, Anders" <> wrote:
> Professor Dredd <> wrote:
> > The bug means that "Data Set Ready" will ALWAYS be
> true when using 
> > the VIC KERNAL. "Clear To Send" also doesn't work
> and the VIC 
> > Programmer's Reference Guide implies as much (so I
> understand).
> So, the obvious question from a stupid luser like me
> will be: do
> these bug(s) prevent proper communication, or was it
> known early
> and programmers would waste a few bytes on copying
> the routines
> to RAM and patch them if needed?

I can only assume that programmers who needed hardware
handshaking wrote their own routines. Could someone
with a VIC-20 PRG please check to see what the exact
word is about CTS?

I never did much telecommunicating on the VIC-20, if
any at all. I think I may have loaded VIC-Term from
cassette once just to watch it work.
> Of course the bugs had to be fixed in the 64, since
> it uses CIA
> instead of VIA, and that is located at a different
> place in the
> memory map..

Yes, you are probably correct about that.

I would assume the VIC-20 bugs were never fixed
because telecommunications from personal computers was
done mostly at 300 baud. At such a slow speed, I
suspect most terminals depended on "X-On/X-Off"
protocol for flow control. It was well suited for such
slow connections.

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