Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!pasteur!ames!killer!elg
From: elg@killer.Dallas.TX.US (Eric Green)
Newsgroups: comp.sys.cbm
Subject: Re: what is this chip(65C802)
Message-ID: <7734@killer.Dallas.TX.US>
Date: 2 Apr 89 04:41:21 GMT
References: <16510@cup.portal.com>
Organization: The Unix(R) Connection, Dallas, Texas
Lines: 30

in article <16510@cup.portal.com>, A-N-Onymouse@cup.portal.com (John - DeBert) says:
$ In article <6460@cbmvax.UUCP> daveh@cbmvax.UUCP writes:
$>can't run at 8MHz using dynamic RAM; 100ns is just the RAS access
$> time.  A minimum 
$>cycle time for such a part is 180ns.  Also consider that, even though the
$>cycle time of an 8MHz part (which you probably can't get anyway) is 125ns,
$>you can only use a fraction of that time for your memory access.  
$>CPU to the DRAM and for decoding.  The 4MHz C64 add-ons use static RAM,
$>probably 100ns parts.  Note also that since the C64 uses a 6510, which has

$ 8MHz is too fast for DRAM? Shhh! Don't tell my HP! It has DRAM and an 8MHz
$ clock. Plus a faster one for the alphagraphics display. :)
$  Seriously, one wonders how one may get DRAM to work with those so-called
$ turbo clones with clocks of at least 8MHz.
$  Also, I have seen 70ns DRAMS advertised from time to time. 

The 8080sux emulates the bus cycles of it's 8080 ancestory, which is
identical to the bus cycle of the Z-80 which we previously discussed.
An 8080sux takes 4 clock cycles to read a byte from the bus. The 6502,
65c02, etc. take 1 clock cycle. Thus a 8 mhz 6502 would be the
equivalent of a 32mhz 8086-based machine. Considering that 80x6-based
machines are having trouble getting RAM fast enough to run at 25mhz
(they're going to static caches, interleaved DRAM, etc.), you begin to
see the memory problems of an 8mhz 6502 (although because it can only
address 64K of RAM, using fast SRAM is certainly a good option).

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