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From: uhclem@trsvax
Newsgroups: net.micro
Subject: Re: NEC V20 8088 compatible microproces
Message-ID: <53400071@trsvax>
Date: Mon, 16-Sep-85 11:05:00 EDT
Article-I.D.: trsvax.53400071
Posted: Mon Sep 16 11:05:00 1985
Date-Received: Thu, 19-Sep-85 05:03:01 EDT
References: <207@ittral.UUCP>
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Nf-ID: #R:ittral.UUCP:-20700:trsvax:53400071:000:2069
Nf-From: trsvax!uhclem    Sep 16 10:05:00 1985


[Hemlock Stones; In "The Case of the Missing Line

Re: Better Processor Look-a-Likes

Sounds like NEC has done the same thing for the 808x series that
Hitachi did for the Z80.  As far as I know, Zilog hasn't bothered to sue.
Perhaps there are enough differences.  (Or maybe Japan buys lots of Exxon fuel)

Their Z80 is called the HD64180.  Apart from adding on-chip MMU,
512k addressing in 64k segments, on-chip two-channel DMA,
on-chip two Full Duplex Asynch channels, on-chip High speed clocked
serial channel (200k Bits/Sec @ 4mhz), on-chip dual 16-bit programmable
reload timers, on-chip interrupt handler (4 ext. 8 int.), and
twelve new instructions including multiply, Hitachi shaved the t-states
on many of the old-opcodes.
Examples:
	JR	cc,address	on the Z80 was 12 t-states for the
	jump and 7-t states for the fall-through.
	On the 64180, it is 8-t for the jump and 6-t for the fall-through.

	LD	r,(IX+offset)	on the Z80 was 19-t. On the 64180, it is 14-t.
	SET	r,(IX+offset)	23-t on the Z80.  19-t on the 64180.
Even the NOP executes in fewer t-states.

Only two problems have presented themselves.  There is an early version that
had some incompatible fall-out in the flags from the DAA (Decimal Adjust)
instruction that some binary-to-hex algorithms take advantage of.  That
appears to have been fixed.  
The other problem is that it isn't pin comtatible with the Z80, (It has
64 pins, the Z80 had 40) requiring you to build a jig to plug it into
existing hardware.  But it's worth it for the speed-up.

Back to the NEC.  I hope they win their countersuit.  Then they can
bring out versions of the ipax#86 series with enough pins/signals so that
other outfits can build x86 emulators, and we can throw away all of the
Intel ICE-boxes (I HATE THAT BLUE BOX!!!).

<The above is my opinion and not that of my employeer.  They don't
 care anyway;  IBM doesn't sell fuel, and they think a blue box gets you
 free phone calls.  That may be true, but I didn't want to call Intel.>

						
						"Thank you, Uh Clem."
						Frank Durda IV
						@ <trsvax!uhclem>


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