🚀 go-pugleaf

In article <smiths.722004482@p4.cs.man.ac.uk> smiths@p4.cs.man.ac.uk (Little SteeeveS) writes:
>A few months ago there was a lot of talk in this group of increasing
> the speed of A310's by replacing the RAM and using a faster crystal
> to clock the machine.
>
>Last Christmas I upgraded my machine to 4Megs (by Craddock Ltd ) and so
> I find myself thinking on these lines...
>In a 4 meg upgrade I believe the old RAM is discarded and completely replaced. Therefore this 4meg is quite modern RAM. Is it therfore capable of going faster?
>i.e. can I whip out my 8MHz crystal and replace it with a 12Mhz one? ( I assume the new Riscos 3 ROMS will survive this but will the new RAM).

I think you can't do this, because the I/O in the machine still has to run
at 8MHz. The newer machines (A5000, A540) have extra circuitry to
synchronise the 12MHz memory with 8MHz I/O. (Or something along those
lines...)

Graham						allan@mnhep8.hep.umn.edu

smiths@p4.cs.man.ac.uk (Little SteeeveS) writes:

>A few months ago there was a lot of talk in this group of increasing
> the speed of A310's by replacing the RAM and using a faster crystal
> to clock the machine.

>Last Christmas I upgraded my machine to 4Megs (by Craddock Ltd ) and so
> I find myself thinking on these lines...
>In a 4 meg upgrade I believe the old RAM is discarded and completely replaced. Therefore this 4meg is quite modern RAM. Is it therfore capable of going faster?
>i.e. can I whip out my 8MHz crystal and replace it with a 12Mhz one? ( I assume the new Riscos 3 ROMS will survive this but will the new RAM).

Don't expect the memory to be able to run faster even if it is newer,
it will always be cheaper to use slow RAM. As for changing the
crystal, the apparent conclusion to the discussion on this group is
that it can't be done, as the same clock feeds the IOC etc. Making IOC
run faster will make the timing of i/o go wrong. The new machines that
use 12MHz memory still use a 8MHz IOC, and some advanced circuitry to
interface these. It would be very difficult (if possible at all) to
add such circuitry to an A310. So I fear we are stuck with 8MHz memory
on our A310's. But our speed can still be improved by using ARM3's,
and in the future by adding FPU's and later ARM chips with write
buffers (which makes slow memory less of a problem).

It would be nice if Acorn (or someone else) would make a new
motherboard with empty sockets that allow us A310 (and A400) users to
plug in the useful chips from our old machines. I can't see this
happening though, as there would not be sufficient economic reason to
do this. But maybe we will be able sometime to buy motherboards of
e.g. A5000 and fit them in our own cases with old keyboards, disks
etc. But don't bet on it.

	Torben Mogensen (torbenm@diku.dk)

In article <1992Nov18.102423.4349@odin.diku.dk>, torbenm@diku.dk (Torben AEgidius Mogensen) writes:

|> Don't expect the memory to be able to run faster even if it is newer,
|> it will always be cheaper to use slow RAM. As for changing the

I've yet to come across a RAM upgrade with memory slower than 80ns..  compared
to the 120ns stuff in your 310, that's a big improvement, and should run
fine on a 12Mhz bus.

|> crystal, the apparent conclusion to the discussion on this group is
|> that it can't be done, as the same clock feeds the IOC etc. Making IOC
|> run faster will make the timing of i/o go wrong. The new machines that
|> use 12MHz memory still use a 8MHz IOC, and some advanced circuitry to
|> interface these. It would be very difficult (if possible at all) to

The advanced circuitry you refer to consists of a couple of PALs which
divide the clock and synchronise bus cycles.

You can certainly speed the bus up on a 400, so I suspect it's possible
on a 300.  Doing so involves a lot of butchery (including cutting tracks,
wire links etc) and some experience with PALs.  If I can get the
disclaimers right, I might post the details (though I plan to try it out
on a /1 and a 300 series first for the sake of completeness).

Cheers

Bob

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  Robert J. Voisey  :  r_voisey@csd.uwe.ac.uk
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