[Coco] Considering new HD6309E based board

[James Igou]

Hey Kip and the others that have replied to my original message.

Things are progressing slowly, but part of that is the additional education
I giving myself and the other side interests that keep popping up.
I have multiple crystals on hand to run the 6309 processor at 2, 3.58, or 4 Mhz.
That will probably evolve into some kind of frequency generator, but right
now this is easier.
I have replaced the 74LS chips I was using with 74HC chips and will
eventually replace most of the glue circuitry with a CLPD.
I have parts to use both the V9958 and V9990 video display processors and
will eventually look at cascading multiple VDPs.
Using GIME or 6847 output as a base layer for something like this may make
genlocking problematic so I am not going to worry about trying that initially.
As to NitrOS9, as OS-9 is not designed to support SMP (in any of its
versions), I would imagine that implementing it in NitOS9 would be problematic.
Also, Boisy Petrie and his friends have the development of this pretty much
under their control.
You will notice that while it is claimed to be an open source OS, that you
can not obtain the source for it.
In any case, asymetrical multiprocessing is still a possibility.
Also, looking at what the mcu market has to offer, VGA output, at least one
RS-232 port and other I/O circuits should be easy to implement.
I am conflicted about what can be used though.
Is it fair to add higher speed 8, 16, or 32 bit micro controller based
devices to something older like the 6309?

Personally, I don't think so.

Oh, and while they are no longer available, at one time I had an XC labeled
6847T1 (with intact pins). The trick was to order them as repair parts from
Tandy. Obviously this is no longer possible and they were discontinued
almost 30 years ago (that in itself is frightening).
I gave mine to Tony D. at Disto so I no longer have it.
Plus, if I remember right, its not a drop in replacement as it consolidated
a couple buffers.
Details for modifying older Coco's to use the 6847T1 were published in
Rainbow by Tony if I am not mistaken.
And, as all the available parts would now have to be salvaged from late
model coco2s (which have soldering in VDGs with shortened pins), it would
probably be more practical to consider pulling GIMEs out of their sockets in
Coco3s.

BTW - As MC68HC000s are now no longer any more expensive than 6309s (if you
know where to buy them), I have been looking at adding these to the mix.
Perhaps if we cannot use NitOS9, as Microware phases out OS-9 for the 68K
perhaps we could consider building something similar but based on the 68k
version.
After all, one of the last projects Ed Gressick discussed with me before he
passed away, was the idea of building a new 6809 board with a GIME for use
in the PT68K4 based System IV computers he was selling.

Jim Igou