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From: knudsen@ihwpt.UUCP (mike knudsen)
Newsgroups: net.micro.6809,net.micro,net.micro.atari16,net.micro.amiga
Subject: Re: New CoCo-III's Market Niche (long)
Message-ID: <1050@ihwpt.UUCP>
Date: Fri, 8-Aug-86 18:01:59 EDT
Article-I.D.: ihwpt.1050
Posted: Fri Aug  8 18:01:59 1986
Date-Received: Sun, 10-Aug-86 04:49:18 EDT
References: <1040@ihwpt.UUCP> <580@cbmvax.cbmvax.cbm.UUCP>
Organization: AT&T Bell Laboratories
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Xref: watmath net.micro.6809:939 net.micro:15311 net.micro.atari16:1577 net.micro.amiga:4251

> > ...possibly with the memory mapping and protection that the
> > 68K pc's lack.
> Has TRS announced an MMU chip for the CoCo-III?  Last I heard, none of the
> 6809 suppliers (Motorola, Hitachi, etc.) had.
Yeah!  The custom VLSI chip that Motorola makes for the Coco3 is indeed
a REAL MMU -- it maps any 8 of 64 physical 8K segments into 6809 address
space.  This chip also includes the graphics, interrupts, and DRAM control.
Since the new Basic has a "protect" option, the MMU may have Read-Only!

> > The Coco III has 128 to 512K, graphics nearly as good as the ST or Amiga...
> 
> Really? 640x400 pixels in 16 colors out of a palette of 4096?  Bit blitter?
> Video coprocessor?  Well, then, how about comparisons to the Atari.  Lets see,
> the Atair gives you 640x400 monochrome.  Nope, can't do that.  640x200 in
> 4 colors out of a palette of 512.  I think the quoted resolution was 640x192
> with 4 colors out of a palette of 64.  Not bad, but if they're really going to
> the added expense of an RGB analog (over RGBI digital) monitor, why settle
> for just 64 colors (2 bits each of R, G, and B).

Yes, I REALLY wish the Coco3 had 384-400 vertical lines.
Personally, I rate resolution more important than palette size,
tho you're right, it's almost a waste of analog RGB to skimp on it.

> Of course, in this price range, you're directly competing with the C128 and
> the Atari 130.  The graphics, is true as
> stated, are better in some ways than either of these.
Yes, this was the main point of my posting.  But I considered 512-640
horizontal pixels to be in the same league with ST and Amiga.

> The C128 ...  supports hardware sprites. 
A lifelong shortcoming of the Coco has been lack of sprite hardware
for games.  It's amazing how well Coco does Donkey Kong, Joust,
and Marble Madness without them.

> The 80 column screen can do 80x25 text, 80x50 text (interlaced),
> and a 640x200 two color bit-map.
I honestly didn't know the C128 could do 640 across -- sorry, and thanks.

> Overall, it sounds like the CoCo-III has an edge
> over the C128 in the display department.
Glad you agree.

> > Tandy has straddled the 68K home market by landing salvos on both sides of it.
> That's silly.  The 68000 machines, any 68000 machine, is much more powerful
> than currently existing MS-DOS machines.  The 6809 is in many ways a more
> advanced processor than the 8088, and at your 1.7MHz or whatever the CoCo-III
> is running faster memory cycles than a standard or XT PClone.  If Motorola
> had the forsight to add on-chip banking like in the 8088, the 6809 would
> have had a good chance of catching on as THE 8/16 bit chip.

Of course we know the 68K machines are better in every way than the MSDOS
biz boxes.  It's just that the 3-piece suit types who define the "real
world" don't see it that way.  Fortunately biz types are finding how useful
color graphics and mouse pointing can be.
I'm glad you appreciate the 6809 so highly.  Interesting idea, putting
segment registers in it, tho the opcodes are long enuf already.

>  Of course, all of the 68000 machines
> will be able to run UNIX quite nicely, along with OS-9 68K, the version of
> OS-9 for grownups.
That's U**X without MMU or protection, as has been argued to death
already.  The Coco3 will do a safer job on OS9 Level II than the
Amiga or ST can on U**X.  Of course OS9/68K is better than 6809 versions,
tho many of the improvements could be retrofit into 6809 versions,
given the extra memory now available.

> Your're right on the code compactness.  Much of the size of the
> code will depend on whether a compiler or an assembler is used and if a
> compiler, how efficient it is.
Boy is that the truth!  6809 OS9 was written in assembler, much of
68K in C, and it shows in the code size.

> Dave Haynie    {caip,ihnp4,allegra,seismo}!cbmvax!daveh
-- 
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