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From: knudsen@ihwpt.ATT.COM (mike knudsen)
Newsgroups: comp.sys.m6809
Subject: Re: 16k Coco purchase query
Message-ID: <1902@ihwpt.ATT.COM>
Date: Wed, 12-Aug-87 13:39:31 EDT
Article-I.D.: ihwpt.1902
Posted: Wed Aug 12 13:39:31 1987
Date-Received: Sat, 15-Aug-87 02:04:43 EDT
References: <1248@ius2.cs.cmu.edu> <668@csuchic.csuchico.UUCP>
Organization: AT&T Bell Laboratories - Naperville, Illinois
Lines: 40
Summary: CoCo OS-9 IS TRUE MULTITASKING!! Just get the right disk controller.

> OS-9 on the Color Computer is not a true multitasking system due to lack of
> DMA and the NMI kludge of the disk controller.  Too many interrupts can (and
> do) get lost.  I'm hoping the CoCo 4 (if Tandy ever gets off its ass) will
> break away from the old CoCo mode and use the real 6809 hardware like the
> 6829 (with 8 of them you can manage two megabytes of memory, or one meg and
> memory protection!), DMA, and maybe even *gulp* multiple processors!
> Ronald Cole				| uucp:     ihnp4!csun!csuchic!ronald

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?)
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.

These new controllers cost about $150 US each.  Whatever you do,
don't buy a Radio Shack controller, since 3rd-party clones at least
as good are available as low as $65 (see _The Rainbow_ mag.).
The Shack's disk drives are also a ripoff.

$170	Coco III
$ 65	Disk controller
$ 90	one DSDD-40 drive
$ 80	OS9 Level 2
$ 70	case, power supply & cable for drive
----
$475 + your TV set or $90 mono monitor

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.
-- 
Mike J Knudsen    ...ihnp4!ihwpt!knudsen  Bell Labs(AT&T)
    Delphi: RAGTIMER    CIS: <memory failure, too many digits>
		"Just say NO to MS-DOS!"