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From: toddpw@tybalt.caltech.edu (Todd P. Whitesel)
Newsgroups: comp.sys.apple
Subject: Re: 20 Mhz 65816
Message-ID: <1990Mar2.081825.28966@spectre.ccsf.caltech.edu>
Date: 2 Mar 90 08:18:25 GMT
References: <10393.infoapple.net@pro-generic> <1990Feb28.232226.7137@spectre.ccsf.caltech.edu> <1154@batman.moravian.EDU>
Sender: news@spectre.ccsf.caltech.edu
Organization: California Institute of Technology, Pasadena
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In article <1154@batman.moravian.EDU> nicholaA@batman.moravian.EDU (Andy Nicholas) writes:

>No, it's NOT microcoded.  Inherently, that's one of Mensch's problems...
>everything on the 65816 is done at the gate level.  He hard-wires EVERYTHING.
>This is one of the reasons that stuff from WDC takes SOOOOoooo long to get out.
>I wish there were some kind of 'super-auto-router CAD program' for Mensch to
>use.  His wife or daughter did the layout for the 65816, which is one of the
>reasons that the chip has problems -- one of the engineers from AE once told me
>that Mensch had told him that the problem with certain instructions not working
>at high speeds was the physical distance that some of the signals had to travel
>inside the chip.  Make of that what you will...

I'll make what I will of the 65816 data sheet:

	"The Timing Control Unit keeps track of each instruction cycle as it is
executed. The TCU is set to zero each time an instruction fetch is executed,
and is advanced at the beginning of each cycle for as many cycles as is
required to complete the instruction. Each data transfer between registers
depends on decoding the contents of both the Instruction Register and the
Timing Control Unit."

If that isn't microcode then PLEASE TELL ME WHAT IS!!

Looks like Mensch is just suffering from the price of cutting corners. He needs
to either redesign his mask so it will be easily manufacturable or maybe he
should license the ASIC guys' mask. (I'd like to see him cooperate with them
to make the 65816 a reality, but I don't know if any of them would go for the
idea...)

Todd Whitesel
toddpw @ tybalt.caltech.edu