[Coco] Is the 6309 worth it?

[Mark Marlette]

Curtis brings up a point here.

Roy J....Have you tried a 32MHZ mod CoCo3 on your SVGA convertor?

This would be great if it work as a standard machine. I always had to 
tweak each monitor that I connected my speed up CoCo3 before.

????

Mark


At 12/6/2006 03:11 PM, you wrote:

>On Wed, 06 Dec 2006 08:55:35 -0600, Roger Merchberger
><zmerch-coco at 30below.com> wrote:
> > There's 3 "modes" to the 6309 - 1) pure compatibility mode - to the
> > software, it's a 6809. 2) "Enhanced 6809" mode: no new instructions, but
> > some instructions take fewer cycles to complete - that's the 15% number
> > you've heard. That can goof up some timing loops in games & whatnot. 3)
> > full 6309 Mode: There are extra registers, extra instructions, extra,
> > extra, extra and some instructions execute even quicker, IIRC.[1]
>
>      Actually, you can use the extra instructions without being in "native
>mode", as most of us call it. The Burke&Burke 6309 patches for OS9
>(original version, anyways), ran in compatibility mode, but with the extra
>instructions. The main differences between native and compatibility mode
>is that the pre-fetch byte is cached, so a lot of instructions are faster
>by a CPU cycle, and that you're IRQ's now push the new W register onto the
>stack as well as the 8 regular registers.
>
> >
> > You get 2 extra 8-bit accumulators, which can also be utilized as a
> > 16-bit
> > accumulator, and *also* with the existing 16-bit accumulator (D) to make
> > a
> > 32-bit accumulator{!} amongst other things.
> >
> > I dunno about the "10x faster" bit, but software written to take
> > advantage
> > of the 6309 can be quite snappy, comparatively (yet vaguely ;-) speaking.
>
>      Yes, some things, particularily block memory moves, can get up to 10x
>faster. This can be used for things as diverse as copying a disk buffer to
>scrolling or clearing a screen. Also, since no hardware divide existed at
>all on the 6809, using the new hardware divide (16/8 or 32/16) is around
>10x faster than doing it through software routines.
>
> >>  It seems like a 32 mhz clock crystal (2.0/4.0
> >> mhz) would do the same thing, and be less sensitive, but what about
> >> compatibility?
> >
> > It wouldn't do "the same thing." The 6309 gains speed due to efficiency,
> > a
> > crystal swap gains speed via overclocking, and remember: you're
> > overclocking the system buss. So, not only will your CPU overheat
> > (because
> > dollars-to-donuts it can't dissipate that much heat with convective
> > cooling) you're also overclocking the memory (which won't be
> > none-too-happy
> > about that!) and the GIME (which quite likely will gesplode) and of
> > course,
> > the video circuitry, which means you won't be able to see how fast your
> > computer's running before it fries.
>     I can honestly say that the 32MHz crystal, except for screwing up
>printer and cassette timing loops, has never caused my 6809 or 6309's to
>overheat much (and never to cause excessive crashing). I have ran 4
>different machines with that upgrade, with both 6809's and 6309's. The
>best case is to put in the crystal upgrade, use a 6309, and run Nitros9
>(but I would be a bit biased that way, wouldn't I? <Grin>
>      The biggest hurdle of using a 6309 is if you use RS-DOS almost
>exclusively... there are only a few programs that properly use it (Sock
>Master's MOD player, Roger's Spyder Hyper & Projector III, and maybe a few
>others. I believe Robert Gault came out with some patches for the Coco 3
>only to allow RS-DOS to run in native mode, getting you that 12-15% speed
>increase, and I know Sock Master had some patches for screen scrolling as
>well, that helped a lot, but not much more than that.
>
>--
>L. Curtis Boyle
>
>--
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>Coco at maltedmedia.com
>http://five.pairlist.net/mailman/listinfo/coco
>
>
>
>
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