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From: ronald@csuchico.EDU (Ronald Cole)
Newsgroups: comp.sys.m6809
Subject: Re: 16k Coco purchase query
Message-ID: <678@csuchic.csuchico.EDU>
Date: Wed, 19-Aug-87 22:57:04 EDT
Article-I.D.: csuchic.678
Posted: Wed Aug 19 22:57:04 1987
Date-Received: Sat, 22-Aug-87 16:10:59 EDT
References: <1248@ius2.cs.cmu.edu> <668@csuchic.csuchico.UUCP> <1902@ihwpt.ATT.COM>
Organization: California State University, Chico
Lines: 43
Summary: Clarifications...

Mike,

In article <1902@ihwpt.ATT.COM>, knudsen@ihwpt.ATT.COM (mike knudsen) writes:
> Both Levels 1 and 2 OS9 can be made into true multitasking systems
> (edit one file while compiling another and printing yet a 3rd),
> IF you buy one of the two new floppy disk controllers coming out
> of Canada -- either Sardis Technologies in British Columbia or
> DISTO in Quebec (anyone in Alberta want to cover the middle?)

Ok, so I didn't give a complete example.  I agree OS-9 is a true multitasking
operating system, but it is crippled on a Color Computer.  OS-9 expects IRQ
to be the way that I/O devices are interfaced.  But does Tandy bring IRQ to
the MultiPak?  Noooooo!  Well, we could use the CART line to get to the
FIRQ line and do in software what should have been done in hardware (a
more reasonable Tandy approach), but only one slot can be attached to
the CART line at a time.  Double-whammy!!  The only reasonable super-kludge
is to make a super i/o board that "does all" from one slot (leaving the
others free for "Robot Battle" and other such crud).

> Both of these cache up at least a sector at a time and transfer
> by nice simple software loops that don't block interrupts or do any
> other non-Ivy_League gaucheries.  The 8K of RAM in the Sardis may
> someday be expanded by software into a real cache of the sort being
> discussed on this net.

I, personally, would have just designed DMA into the new CoCo 3 and solved
all these kludgy solutions once and for all!

> PS: Motorolas's old MMU chips (6829) waste a clock cycle on every
> RAM access.  Tandy's new custom GIME chip does not.
> I posted months ago about how easily Tandy could extend the GIME
> to 2 Meg.  Let's not wish Tandy back to obsolete off-shelf chips.

Ok, for the sake of speed, you have me there.  I see that you also rag on
Tandy; they kinda "half-ass" things, don't they.  If they would concentrate
on making the CoCo g_o_o_d_ and not c_h_e_e_p_, they would sell just as many units.
Still, multiple processors in a CoCo 4 would still be a +.  ;^}

-- 
Ronald Cole				| uucp:     ihnp4!csun!csuchic!ronald
AT&T 3B5 System Administrator		| PhoneNet: ronald@csuchico.edu
@ the #_1_ party school in the nation:	| voice     (916) 895-4635
California State University, Chico	"It's O.K." -Hal Landon Jr., Eraserhead