4 Mar
2008
4 Mar
'08
5:12 a.m.
woodelf wrote:
Jim Brain wrote:
A) Fine, if that's the game we're playing, direct zpage to non-zpage
copy it is.
B) You did not specify high speed. You specified multi-tasking. I
would agree 5 minutes between task is not multi-tasking, but all 3 of
the examples noted could do a task switch in 4096 cycles, or 4ms. I
think that qualifies for speedy. Tasks were switched on the Jiffy CLOCK
as part of the 50/60 Hz IRQ, meaning they each got about 12000 cycles of
time. Definitely speedy enough for a 1MHz machine.
jim
woodelf wrote:
A) Dma is cheating
B) Well two tty's at 110 baud must be high speed multi-tasking :)
I suspect any OS using the 6502 can't have multi-tasking OS
because you can't change page 0 or the stack page.
Define "change"?
LUnix and BOS (unfinished multitasker from the
creator of ACE), as well as my BRIX could "change" zpage and stack on
a 6502. It took either using the REU DMA or simply copying the page
to another location in memory, but it worked.