Path: utzoo!utgpu!attcan!uunet!husc6!cmcl2!rutgers!uwvax!oddjob!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.arch
Subject: Re: What's a "tahoe"?
Message-ID: <12851@mimsy.UUCP>
Date: 5 Aug 88 10:53:26 GMT
References: <6341@bloom-beacon.MIT.EDU> <60859@sun.uucp> <474@m3.mfci.UUCP> <3420@phri.UUCP>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 35

In article <3420@phri.UUCP> roy@phri.UUCP (Roy Smith) writes:
>For months I've been listening to people talking about "4.3-tahoe"
>but I still havn't seen anybody explain what a "tahoe" is.

The Tahoe is a series of machines (as the VAX is a series).  Tahoes are
sold by CCI, Harris, Sperry/Unisys, and by one other company whose name
I have forgotten.

The original Tahoe was the CCI Power 6/32, a ~6-VAX-MIPS box with
(uh oh) VERSAbus-based disk and tape drives.  VME-based peripherals
are now available for this CPU.

The Tahoe has been called a `RISC': Reused Instruction Set Computer.
The Tahoe architecture is remarkably similar to that of the VAX;
however, many of the special purpose instructions are missing (no
branch on bit set and clear interlocked, e.g.), many of the fancier
addressing modes are missing; and the basic instruction cycle is much
faster (the CCI is mostly TTL, yet runs about as fast as the ECL gate
array VAX 8650).  (Whether the speed difference can be attributed to
leaving out the fancier instructions and addressing modes is a topic
for another raging comp.arch controversy :-) .)

4.3BSD-tahoe runs on the original CCI Tahoe and (as far as I know) on
the Harris HCX-7.  It may soon run on the HCX-9.  I believe the Sperry
7000 is identical to the HCX-7, so it should run on that too.

4.3BSD-tahoe also runs on the VAX 11/750, 11/780, 11/785, 8200, 8250,
8600, and 8650, on the MicroVAX-II, and possibly on the VAX 11/725 and
11/730 (this has not been tested).  The tape from Berkeley has Tahoe
binaries rather than VAX binaries, but the full source tree is present,
so installation on a VAX is largely a matter of replacing the old
sources and recompiling.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris