CoCo vs. C64 duke it out

[Jim Brain]

woodelf wrote:
> Jim Brain wrote:
>> woodelf wrote:
>>>
>>> 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.
>
> A)  Dma is cheating
> B) Well  two tty's at 110 baud must be high speed multi-tasking :)
>
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