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From: freeman@spar.UUCP (Jay Freeman)
Newsgroups: net.micro
Subject: NEC V20 -- seems to work
Message-ID: <756@spar.UUCP>
Date: Tue, 7-Jan-86 15:24:22 EST
Article-I.D.: spar.756
Posted: Tue Jan  7 15:24:22 1986
Date-Received: Wed, 8-Jan-86 20:44:44 EST
Reply-To: freeman@spar.UUCP (Jay Freeman)
Organization: Schlumberger Palo Alto Research, CA
Lines: 52

[]

A while back, there was some net discussion about NECs new processors
that are pin-compatible upgrades of the Intel 8088 and 8086.  I recently
bought an NEC V20 -- the 8088 upgrade -- and installed it in place of 
my home computer's 8088.

My machine is a Micromint MPX-16, which was a Steve Ciarcia project in
Byte for November 1982 through January 1983.  In hardware features, it
roughly resembles a "disunbundled" IBM PC.  Mine has two DSDD 5.25-inch
floppy disc drives, an 8087, 896K DRAM, a serial terminal (no bit-mapped
display), and runs CP/M-86.

The MPX-16 runs at a nominal 4.7 MHz clock.  As cheap insurance, I bought
the 8 MHz version of the new processor.  (My system clock remains 4.7 MHz.)

With the NEC V20 installed in place of the 8088, everything seems to run.
The machine boots, the various CP/M-86 utilities do their respective 
things, word processors operate, and my C compiler (Mark DeSmet's v. 2.41)
functions.  I don't use the 8087 much, but a few tests of transcendental
functions, via a "desk calculator" program, give the correct results.
(This program accesses the 8087 through the 8087 support library that
comes with DeSmet's compiler.)

I have played with the V20's 8080-emulation mode via the debugger.
A few short routines work as advertised.  I have not yet gotten around
to trying any of the 80186 instructions that the V20 supports.

Knock on wood, I have seen no mysterious crashes or failures that might
be attributable to the new processor.  (I write lots of system code, so
I see plenty of garden-variety crashes and failures.)

The V20 is observably faster in many applications, particularly in a
word processor I have, that uses block moves extensively to shuffle data
in text buffers.  The V20 is rather more than twice as fast as the 8088
on block moves -- 8 clocks per byte versus 17 -- and it shows.  My system
uses half a meg of its on-bus RAM as a memory disc, whose driver uses 
the block move instruction to read and write the "disc":  Thus any 
program that either uses the memory disc or is stored there, will be sped 
up somewhat.

The NEC chip cost about $30.  8088s presently run between $5 and $10.
The rest of my system is probably worth between $1K and $2K.  For a one
percent cost increase, the improved performance of the V20 seems well
worth having.  I hope the legal controversy between Intel and NEC is 
settled in a way that makes the V20 available.  It would still be worth
it if the cost were increased several dollars by a license agreement.

If there is anything special anyone would like me to try, send mail.
I have no way to port code or source from my net address to home, so
I probably will ignore any long test programs I get.
-- 
Jay Reynolds Freeman (Schlumberger Palo Alto Research)(canonical disclaimer)