[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [f-cpu] some technical stuff (yeah :-D)



On Fri, Jun 15, 2001 at 01:45:55AM +0200, Yann Guidon wrote:
[...]
> > What about a variable internal clock?  Using a (programmable) NCO,
> > we could increase/decrease the clock frequency without any glitches.
> that's what i consider most.
> On top of that, the clock can be controlled by a HW real time controller
> which analyses how many instructions are executed etc...
> so the NCO can be matched to the real CPU activity.

I'd rather add another special register that allows the CPU to change the
NCO frequency.  Analysing usage patterns, detecting idle periods and so
on is the operating system's task.

> i'm pretty sure that somebody has already patented it bu why care ?

I don't know.  Several CPU vendors use programmable clocks (combined
with variable core supply voltages) in their low-power/"mobile" CPUs.
I don't know *how* they do it, but an NCO is the obvious way, IMHO.
And it's rather easy to implement (two registers and an adder).  The hard
part is to keep the F-bus and the SDRAM-interface going at the same
speed all the time.

-- 
 Michael "Tired" Riepe <Michael.Riepe@stud.uni-hannover.de>
 "All I wanna do is have a little fun before I die"
*************************************************************
To unsubscribe, send an e-mail to majordomo@seul.org with
unsubscribe f-cpu       in the body. http://f-cpu.seul.org/