RE: VIC 26 Lines Bug - Truth or Legend ?

ncoplin_at_orbeng.com
Date: 2001-08-20 06:26:08

JP> Does this hack involve running PAL machines with a NTSC crystal?
JP> As far as I know, the 6510 runs at ~1 MHz for NTSC machines. It
JP> would be super cool if there's a way to overclock to 1.3 MHz
JP> easily. But somehow I think this will only work on PAL..

>You put a switch over the PAL/NTSC jumper. The jumper controls the
>clock frequency divider -- /18 for pal and /14 for NTSC iirc (probably
>not, just got home from the pub :). The vic won't be able to show any
>graphics -- or at least 15 kHz monitors won't be able to display it.

You can also configure a bit from the datasette port (and an inverter?) to
control the switching via software. Using the borders trick which is done
with 2MHz you can get some speed-up and some display, but with full screen
viewable its only a 9% increase.

I tried this trick also with a C128 (speeding it up to 2.66MHz) but the VIC
chip in that machine doesn't like it too much and it works for a few minutes
then becomes unreliable... works the next day, so no permanent damage!

- Nick


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