From: Christian Johansson (c64_at_comhem.se)
Date: 2004-07-01 18:50:21
> > I think that your calculations may not be correct for the Hug routine.
> > These are the values used by that routine and they are different from
what I
> > get with your calculations:
> >
> > ; Start bit times.
> > ;
> > strt24 .word 459 ; 2400
> > strt12 .word 1090 ; 1200
> > strt03 .word 4915 ; 300
> > ;
> > ; Full bit times.
> > ;
> > full24 .word 421 ; 2400
> > full12 .word 845 ; 1200
> > full03 .word 3410 ; 300
>
> If you multiply the above figures, e.g., 421*2400, you should get the
> processor clock speed in Hz. Most figures are around 1.1 MHz. The
> PAL VIC-20 clock speed is 17734472 Hz/16 (and not /18 as on the C64 and
C128),
> or 1108404 Hz. So, the figures look quite okay.
[CJ] There's only one problem with this. The figures above are taken from a
listing for C64/C128 and NOT for the VIC-20. The original poster of this
thread wondered how to modify the routine for the VIC-20 but I'm more
interested in how to modify the routine for getting 4800 bps on the C128
(which should be possible if you use 2 MHz I think).
>
> On the PAL C64 and C128, you should use 985248 Hz as the base value.
> If I remember correctly, the NTSC VIC-20 runs at the same clock speed
> as the NTSC C64 and C128, 14318181 Hz/14=1022727 Hz.
>
> Marko
>
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