Re: RS-232 on VIC-20

From: Christian Johansson (
Date: 2004-06-21 19:51:54

----- Original Message ----- 
From: "MagerValp" <>
To: <>
Sent: Monday, June 21, 2004 7:13 PM
Subject: Re: RS-232 on VIC-20

> >>>>> "CJ" == Christian Johansson <> writes:
> CJ> Has anybody been able to use the Hug RS-232 routines to get 4800
> CJ> bps on the C128? I think it should be possible since if it is
> CJ> possible to achieve 2400 bps on the C64 in 1 MHz with the
> CJ> routines, it should also be possible to achieve 4800 bps on the
> CJ> C128 in 2 MHz
> Well, actually, the biggest problem is badlines - and they're 40 us
> long even in 2 MHz mode. In 80 column mode with the VIC screen closed
> it's possible to use 9600 bps though.

I'm not very familiar with badlines. Does that problem exist even if I blank
the screen in 40-column mode? Of course, I blank the screen when using the
40-column mode with 2 MHz because there is not much point in seeing a lot of
garbage moving across the screen. Anyway, I have tested that it is only
possible to achieve 2400 bps with the built-in Kernal routines in 2 MHz mode
and 80-column mode but I know that it is possible to achieve 9600 bps using
custom routines (and 115200 bps if you stop using interrupts and use code
like in Over5). What I want to know is if the Hug routine I posted in my
previous email could perhaps be used to get at least 4800 bps by making some
small modifications to it. I think it should be enough to change the
definitions of the bit times but as I wrote I don't understand how they have
been calculated.

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