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From: knudsen@ihwpt.UUCP (mike knudsen)
Newsgroups: net.micro.6809
Subject: Re: CoCo III - Still a Rumor?
Message-ID: <898@ihwpt.UUCP>
Date: Thu, 5-Jun-86 18:38:15 EDT
Article-I.D.: ihwpt.898
Posted: Thu Jun  5 18:38:15 1986
Date-Received: Sat, 7-Jun-86 14:01:24 EDT
References: <115@safari.UUCP> <3500153@uokvax.UUCP>
Organization: AT&T Bell Laboratories
Lines: 38

> A new CoCo would have those limitations inherent in the 6809, but would not
> have all those of the current CoCo.  PDP-11s have gotten along for a while
> with 64K per process...
> 
> While I can understand your sentiments, and deplore Tandy's joining the
> bandwagon of International BM TLs (see *The Joys of Yiddish* for the
> definition of "TL"), one can nevertheless do a great deal with a 6809,
> and an improved CoCo would be by far the least expensive reasonable
> multitasking system one could buy.
> 						James Jones

One thing that worries me about a Level II 6809 system is that
the standard Motorola chip for this adds another cycle to every memory
access.  Since the 6809 already wastes one cycle internally for every
access (relative to the 6502 and to common sense necessity, not
counting the second cycle wasted on adding backwards bytes in indexed
addresses), a Level II Coco would be really slow.

Of course the clock speed could be doubled (if some new graphics
chip were used besides 6847) which would more than compensate.

Also, it seems that TTL logic could be used to build an MMU or DAT
that would be fast enough to avoid missing a cycle; this logic
could be put in a gate array or PAL.  This would require Tandy
to do some original design work of their own -- an event less likely
(and maybe less desirable?) than World War III.
(OK, that's unfair -- the Coco cassette interface, easily the best
ever produced, was *not* copied out of the Motorola book.)

Still wondering why Tandy didn't put a CTRL key and lower case
in the Coco years ago, plus monitor output -- these could have
been easily added to newer models without interfering with
older hardware/software or user habits.

mike k

Coco is a beach near Cape Canaveral.
Tandy is a euphemism for Radio Shack.