> 
> Joe Smith said:
> > 
> > > From: cs_yus@cs4.lamar.edu (YU SONG)
> > > To: amiga@NetBSD.ORG
> > > Subject: cache
> > > 
> > > 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.

Um, almost. The A4000 has a shitty RAM interface. An A3000 with an A4000
CPU card will run MUCH faster than an A4000 with an A4000 CPU card.

The A4000 sucks. The A1200 can access chip memory faster than an A4000.

> 
> 	Well, actually it's that the Amiga's CPU's (well, all 680x0 CPU's) are
> clocked so slow (relative to other CPU's), and that the motherboard data paths 
> are well designed - resulting in 80ns RAM being all that's needed without 
> a significant bottleneck.
> 
The A3000 can take 70ns RAM, but you only get about 1ns of improvement.
This data came from an AmigaDOS writer who got it from Dave Haynie.

>         However:
> In the A3000 and A4000, a CPU in the "CPU Slot" will have pathetically slow -
> in terms of MB/s, about 1.6 - access to motherboard memory..  While on L2 cache
(snip)

Double check this for the A3000, please.

> 	The problem is not that the motherboard datapaths are bad, but because 
> the CPU and motherboard are on different clocks.  
> 
The datapaths on the A4000 are bad.

XCOMM --------------------------------------------------------
XCOMM Kevin P. Neal, Sophomore CSC/CPE     kpneal@eos.ncsu.edu 
XCOMM North Carolina State University      kevinneal@bix.com
XCOMM --------------------------------------------------------