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 > > Message was sent through the cbm-hackers mailing list Message was sent through the cbm-hackers mailing list
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