Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!gatech!ncar!boulder!unicads!les
From: les@unicads.UUCP (Les Milash)
Newsgroups: comp.arch
Subject: 29K
Keywords: my *new* favorite chip :-)
Message-ID: <624@unicads.UUCP>
Date: 8 Sep 89 16:25:44 GMT
References: <21936@cup.portal.com> <7851@cbmvax.UUCP> <27133@proton.mips.COM>
Reply-To: les@unicads.UUCP (Les Milash)
Organization: Unicad  Boulder, CO
Lines: 32

In article <27133@proton.mips.COM> wilkes@mips.COM (John Wilkes) writes:
>In article <7851@cbmvax.UUCP> daveh@cbmvax.UUCP (Dave Haynie) writes:

>doesn't the amd 29000 have external i and d busses?  it's been a long time
>since i looked at that chip...

roger.  they share the addr-out bus; they want to emit an i-addr and expect
the memory system to stream successive inst's in on its own.

also this chip works well with the vram trick, fetching inst's out of the
vram's serial port, except it looks like they're gonna be faster than vrams
pretty soon; they're already interleaving vrams.

V3 Corp (in toronto i think) makes a 1-chip 0-glue dram controller that does
all the right stuff, so a minimal system looks like 3 pga's and dram.

the chip's got a voracious appetite for memory, but they've done lots of 
tricks to keep from hitting on the dram.

they also have a "branch target cache" so that during a branch they can execute
3 inst's, if your i-mem can start delivering inst's that fast you never have to
stall.

all in all a clean&fast chip; i love it.  (but i haven't seen the RX000 or 88k 
yet).

Requires
Investment in
Static-ram
Computer

Les