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From: mikey@trsvax
Newsgroups: net.micro
Subject: Re: NEC V20 8088 compatible microproces
Message-ID: <53400064@trsvax>
Date: Wed, 4-Sep-85 11:50:00 EDT
Article-I.D.: trsvax.53400064
Posted: Wed Sep  4 11:50:00 1985
Date-Received: Sat, 7-Sep-85 13:48:06 EDT
References: <207@ittral.UUCP>
Lines: 26
Nf-ID: #R:ittral.UUCP:-20700:trsvax:53400064:000:1144
Nf-From: trsvax!mikey    Sep  4 10:50:00 1985




The V30 is the equivilent part for the 8086, the V20 is the 8088 chip. 
As I understand it, the V20 and V30 are not anywhere close to the same
as their Intel brothers internally, just that they operate the same or
faster, and at a lower power level (they're CMOS).  

The V20 executes some instructions up to 30% faster and in addition, 
supports the 80186 op codes for bit manipulation and stuff like
PUSHA and POPA.  The V20 also has a native 8080 mode that allows 
execution of 8080 code in either a 64K model or a 128K model (separate
code and data segments).  

Overall, they are quite a powerful chip set.  I have run into some
problems using a V20.  There was one program that worked ok with 
the 8088, but died with the V20.  I traced it down with debug and
discovered a place where the programmer accidentally executed a data
area.  Since the 8088 ignored some opcodes that the V20 uses, that
was the difference.  I put a jump around the erroneous data area 
and both processors now worked fine.  (It also cleared up an obscure 
bug in the program)

mikey at trsvax

ps. There is also a similar CMOS part for a Numeric Coprocessor.