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Re: [f-cpu] optional SRB



And where is the stack pointer ????? F-cpu has no dedicated stack pointer
!!!

----- Original Message -----
From: "Antoine" <antoine@rezo.net>
To: <f-cpu@seul.org>
Sent: Sunday, November 24, 2002 10:05 PM
Subject: Re: [f-cpu] optional SRB


>
> > 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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