Re: [Vice-emu-mail] X64SC Monitor, chis, unaccounted clock cycles.

That is very interesting and this is the first I have heard about this.  I
had no idea that the VIC-II has the capability to suspend CPU activity, as
least what is visible to the user via the chis tool in the monitor.  It has
been such a long time (early 1990s) since I heard/read about DMA on a
Commodore product.  I had to read up on DMA as well.

On Sun, Aug 10, 2025 at 1:26 PM gpz via Vice-emu-mail <
vic...@li...> wrote:

> Am Sonntag, 10. August 2025, 13:09:36 Mitteleuropäische Sommerzeit schrieb
> timothylegg:
> > I am using x64sc 3.9 (GTK3 3.24.41, GLib 2.80.0, Cairo 1.18.0, Pango
> > 1.52.1) which I'm pretty certain is compiled from source.
> >
> >
> > Last week, I used chis for the cpu_history and I noticed something
> > peculiar...
> >
> > C:c402  A9 10       LDA #$10       A:0e X:6f Y:00 SP:d8 .V-..I.C
> >  191041395
> > .C:c404  9D 00 C0    STA $C000,X    A:10 X:6f Y:00 SP:d8 .V-..I.C
> >  191041397
> > .C:c083  48          PHA            A:10 X:6f Y:00 SP:d5 .V-..I.C
> >  191041452
> > .C:c084  AD 18 C0    LDA $C018      A:10 X:6f Y:00 SP:d4 .V-..I.C
> >  191041455
> > .C:c087  4A          LSR A          A:0e X:6f Y:00 SP:d4 .V-..I.C
> >  191041459
> >
> > Does anyone know why the STA (9D) take 55 clock cycles?  From the MOS
> > datasheet, I see that it should be 5.  Is this a bug in the emulator or
> is
> > there something quirky with the C64 hardware that I don't know about yet?
>
> My guess would be that there was DMA going on ("badline" and/or sprites)
>
>
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