Subject: Re: cache
To: Jukka Marin <>
From: Geert Uytterhoeven <>
List: amiga
Date: 03/26/1996 10:15:31
Jukka Marin wrote:
> > > However, as I was 
> > > told before that the memory access in stock Amiga ( A4000 in my case )
> > > is quite slow.
> > 
> > You have been misinformed.  Memory access in the Amiga between the CPU and
> > fast RAM is quite fast.  So fast, that adding an L2 cache will not make it
> > any faster.
> The A4000 FAST RAM is pretty slow, indeed.  It is slower than the FAST RAM
> of A3000.  However, the A4000/40 has a faster CPU which really suffers
> from the slow memory.  The performance is probably around 50% of what it
> _could_ be (I've heard that the Motorola VME boards are very fast (but then,
> the also cost a lot)).

You can get about 10 MB/s (12 MB/s with SpeedRamsey) from the '040 to the A4000
motherboard RAM. Turning off all caches slows down the system by a factor of
about 12, so there really is a big leap between RAM access and '040 internal
cache access.



Geert Uytterhoeven           
Wavelets, Linux/m68k on Amiga
Department of Computer Science -- Katholieke Universiteit Leuven -- Belgium