68hc000 schematics and processor wars

[John S Gwynne]

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Processor wars:

Although I've decided to use the 68hc000 (with the intent of switching to a
CPU32 variate latter, much latter), I encourage each of you to work with the
processor of your choice. In my eyes, it's more important that we build
something that works and less so of the exact details. I don't see the
processor (or electronics) as the critical element of this project.

(With that said, you other guys will be hard pressed to duplicate the software
environment of the 68k with those *other* CPUs :) :).  )

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68HC000 schematics/update:

Last week I transfered a front and back "pictures" of the 68HC000 board (two
tiff files) to Robert Fridman for inclusion into the WWW server (Thanks,
Robert).  I had some problems getting the schematic into a form we could all
work with, but, with some help from a colleague, I think we have it.

-schematics. The schematic can now be retrieved through this mail server. The
file is 68hc000-0.90.ps. Send help to Majordomo at coulomb.eng.ohio-state.edu
for details. This postscript file outputs ten pages that when printed on
8.5x11 pager, and are taped together, form a D-sized drawing. There are some
minor change that are not up-to-date on this schematic.  (pin 16 of IC1 goes
to ground, pin 15 of ic18 is grounded, and several sections of ic7, ic2, and
ic3 where swapped to minimize wire path length). All simple things that I
will have changed by the next version.  If there is interest, I could make up
some kind of a parts list etc...

-board version. I deemed this version 0.90. The next version (by the end of
the year) will replace the 74ls123a (ic10) with a Maxim supervisory ic (watch
dog/battery switch over/reset generator), and include an interrupt priority
encoder and a "heart beat" 100mS interrupt. This is a minor 3-4 chip change.

-A companion board is in the works.

-Real Time Executive for Military Systems (RTEMS) will become the kernel for
the board. I'm almost ready to port it; I know what needs to be done but
haven't done it yet. There are maybe 300-400 pages of documentation, 100
pages of C-code, and *lots* of flexibility. It will be "real-cool" once it
comes together.

-I expect spark timing will be the first thing implemented. Maybe yet this
year. (ok, by spring?)

                                       John S Gwynne
                                          Gwynne.1 at osu.edu
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