Re: [f-cpu] optional SRB

[Antoine <antoine@rezo.net>]

> 	I reread the chapter named "ISA modularity" and I have a little problem. If 
> we trust this paragraph, the SRB is optional, or I think that's totally 
> impossible to write an OS without it. I don't know if the idea is to be able 
> to create F-CPU where only one application can run or if it's a mistake.

It's quite simple to solve IMHO. On a context switch (IRQ/trap/...),
the current PC could be stored in a special register, so as to be 
restored at the end without any need for SRB.

Of course, the IRQ/trap/syscall handler should actually store the
SR somewhere else as soon as possible, so as to avoid crashing if
the handler itself is interrupted (besides, the OS would take care
that all handlers are locked in memory - i.e. can not be swapped to 
disk).

This is much simpler than making the SRB mandatory.


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