5 Jun
2014
5 Jun
'14
7:34 p.m.
On 05/06/14 13:26, Brantley Coile wrote:
This method wasn't original to me. It was common
practice at the
time. I assume this the technique used by AmigaDOS.
I have no direct knowledge of AmigaDOS, but since there was no hardware
protection between processes and all processes shared the same address
space, context switching COULD BE just "store process registers,
including stack pointer and Program Counter, for process A", "restore
process registers, including stack pointer and program counter from
process B".
Certainly I did this in the 8 bit era (well, 6502 CPU have the stack in
a fixed position but only just 256 bytes long, so I just copy it around
when doing context switching) and in Atari ST (68000 based computer).
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