This code allows you to turn on & off the fast mode when in 64 mode of the 128....

10 rem copyright 1988 compute! publications, inc. - all rights reserved
   20 print"{clr}   copyright 1988 compute! pub., inc."
   30 printtab(10)"all rights reserved{down}"
   40 forc=828to954:readd:pokec,d:cs=cs+d:next
   50 ifcs<>11484thenprint"there is an error in the data statements":end
   60 print"sys 828 to enable key toggle":print"sys 831 to disable key toggle"
   70 print"sys 834 for fast mode":print"sys 837 for slow mode":end
   80 data76,72,3,76,102,3,76,159
   90 data3,76,173,3,120,173,20,3
  100 data141,52,3,173,21,3,141,53
  110 data3,169,117,141,20,3,169,3
  120 data141,21,3,88,169,12,141,54
  130 data3,96,120,173,52,3,141,20
  140 data3,173,53,3,141,21,3,88
  150 data96,173,54,3,208,29,165,203
  160 data201,4,208,26,173,141,2,201
  170 data4,208,19,169,1,77,48,208
  180 data141,48,208,169,12,141,54,3
  190 data108,52,3,206,54,3,165,203
  200 data108,52,3,173,17,208,41,139
  210 data141,17,208,169,1,141,48,208
  220 data96,173,17,208,9,16,141,17
  230 data208,169,0,141,48,208,96

Awesome, I knew there was a "BASIC" way to do this.  and well it means ML encoded in DATA statements but hey, it's still basic ;-) hehe.

Thanks a lot. :-)

Hi Commodor, thanks for your program. Could you please tell us what key it installs a speed toggle on?
(BTW such a key toggle would be great in C128 mode, too... something like checking 40/80 Display in IRQ ... gonna post that sometime soon...)

Although, for switching between 1 and 2 Mhz mode in C64 mode "manually" no program is needed, simply alterating the VIC register will do:
POKE 53296,1:REM FAST
POKE 53296,0:REM SLOW

As this location on a real C64 by default will have all bits set, PEEKing into into is a convenient way of telling if it's C64 or C128 in C64 mode - even in FAST mode, a C128 will have bit #1 unset (which is for Hold VIC and unused by the Kernal and very most programs.)
 
If you're annoyed by the garbage screen, just turn of display by resetting the appropiate VIC bit like the BASIC 7.0 FAST/SLOW commands do.

In any case, don't forget switching to 1 Mhz before disk access, else the C64 kernal is going to crash (as it of course doesn't switch to 1 Mhz automatically during disk access).

Greetings,
George

awesome..thanks:tummenupp: