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From: jkg@pyr.gatech.EDU (Jim Greenlee)
Newsgroups: comp.sys.ibm.pc,comp.unix.xenix
Subject: more V30 stuff
Message-ID: <4157@pyr.gatech.EDU>
Date: Sun, 4-Oct-87 02:31:12 EDT
Article-I.D.: pyr.4157
Posted: Sun Oct  4 02:31:12 1987
Date-Received: Wed, 7-Oct-87 05:36:01 EDT
References: <407@auscso.UUCP> <189@megatek.UUCP>
Reply-To: jkg@pyr.UUCP (Jim Greenlee)
Distribution: world
Organization: Georgia Institute of Technology
Lines: 33
Keywords: NEC V30 80186
Xref: mnetor comp.sys.ibm.pc:8648 comp.unix.xenix:894

In article <189@megatek.UUCP> hollen@mana.UUCP (Dion Hollenbeck) writes:
>Yes, indeed the V30 will execute 80186 code. It even has some instructions
>which extend beyond the 80186 (f'r'instance - execute Z80 code).  

Well, I don't know about 80186 code, but it definitely does NOT execute
Z80 code (not all of it, anyway). The V20/30 executes *8080* code, which
is a subset of Z80 code (actually, it is proabably more appropriate to
say that Z80 code is a superset of 8080 code). The Z80 was designed to be 
object-code compatible with the 8080, but with an enhanced instruction set. 
Zilog also redefined the instruction mnemonics. 

The V20/30 toggles into emulation mode by means of a software interrupt, 
so the 8080 instructions are more of an "instead of" than an "extension to"
the 80x86 instruction set. In fact, there is a shareware program (V2080.COM)
that does this, allowing some CP/M software to be executed directly on PC 
compatibles at full speed.

>I have
>a manual for the chip and would be glad to give a reference for how to
>get one if any interest.  

Maybe you should read it :-). Actually, I heard a rumor about a year ago
that NEC was working on a new chip in the V series that WOULD execute Z80 
code directly - it was to be called the V25/35. No doubt it was delayed 
as a consequence of the lawsuit by Intel. No use dragging Zilog into the
fray, right? :-) Can anybody { confirm | deny | embellish } this?

						Jim Greenlee
-- 
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