Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!bu-cs!husc6!rutgers!rochester!pt.cs.cmu.edu!ius3.ius.cs.cmu.edu!ralphw
From: ralphw@ius3.ius.cs.cmu.edu (Ralph Hyre)
Newsgroups: comp.sys.apple
Subject: Re: multitasking
Message-ID: <4708@pt.cs.cmu.edu>
Date: 13 Apr 89 18:57:59 GMT
References: <8904061416.AA20685@decwrl.dec.com>
Organization: Carnegie-Mellon University, CS/RI
Lines: 74

In article <8904061416.AA20685@decwrl.dec.com> secrist@msdsws.DEC.COM ("Richard C. Secrist") writes:
>	Even the CoCo I can multitask under OS-9 but anybody who has
>	ever tried it can tell you it was a real dog.  Of course that
>	was on a 0.8 MHz 6809E

A Zip chip or something would make it worthwhile.  My cycles are more
important, and if I can avoid having to recreate my environment by
letting the machine keep multiple instances around, then I'm happy.

I think most of the CoCo's problem was a problem with the R/S disk 
controller.  It's still not an Amiga, but where else can you multitask
for less than $500? (C64 + GEOS, I suppose).

Article 413 of comp.sys.m6809:
Path: pt!rochester!ur-tut!sunybcs!boulder!hao!ames!ptsfa!ihnp4!ihwpt!knudsen
From: knudsen@ihwpt.ATT.COM (mike knudsen)
Newsgroups: comp.sys.m6809
Subject: Re: 16k Coco purchase query
Summary: CoCo OS-9 IS TRUE MULTITASKING!!
	 Just get the right disk controller.
Message-ID: <1902@ihwpt.ATT.COM>
Date: 12 Aug 87 17:39:31 GMT
References: <1248@ius2.cs.cmu.edu> <668@csuchic.csuchico.UUCP>
Organization: AT&T Bell Laboratories - Naperville, Illinois
Lines: 40

> 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!"
>
>	rcs

-- 
					- Ralph W. Hyre, Jr.
Internet: ralphw@{ius{3,2,1}.,}cs.cmu.edu    Phone:(412) CMU-BUGS
Amateur Packet Radio: N3FGW@W2XO, or c/o W3VC, CMU Radio Club, Pittsburgh, PA
"You can do what you want with my computer, but leave me alone!8-)"
--