[N8VEM: 16295] new 6x0x board project

[Andrew Lynch]

[note: this went out to the N8VEM mailing list. This only FYI to CCTALK in
case anyone here is interested in participating in the 6x0x redesign
project. The proposed 6x0x schematic and PCB layout files are at
http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder&param=ECB%206x0x ]



Hi!  Sorry for the long message.  I have a lot to say about a new N8VEM
board project and am asking for your help.

I think the 6x0x host processor, 6x0x IO mezzanine, and 6x0x ECB backplane
are in need of a redesign and PCB respin.  The three board “sandwich”
approach has some major limitations and has led to some really weird and
unnecessary complications.  All the 6x0x PCBs are out so this is a great
time to rethink the whole approach.

Some builders and I have been discussing the topic and it dovetails nicely
with some other improvements builders have been asking about.  For example,
it would be nice if we had a form factor that leveraged more easily stock
ATX cases and power supplies.  Also the ability to use 6U chassis with
Eurocard backplanes (aka VME) form factor would help.

Attached are notional redesign of the 6x0x board series into a single
integrated board.  It is still an ECB board but as a bus controller rather
than as a peripheral like the 6x0x host processor.   The new 6x0x board
includes the dual CPU socket for 6502, 6809, and 6802 compatibility as well
as all the IO from the 6x0x IO mezzanine (serial, parallel GPIO, timers,
etc).  As it is no longer a peripheral on the ECB bus it now includes a
variant of the ParPropPort built in to provide full builder interface such
as VGA display, PS/2 keyboard, SD mass storage, speaker, etc for complete
standalone capability.

Please review the proposed 6x0x schematic and PCB layout files and send me
any changes and/or corrections.  The new board is ATX and 6U chassis
compatible.  You can mount it in a stock ATX case and use a stock ATX power
supply unmodified.  Likewise with a 6U chassis.  I am very interested in any
discussion points on the 6x0x however please keep in mind this is an
incremental step to addressing broader issues with the N8VEM collection of
boards.  You can still keep it out of a case altogether and set it on your
workbench if you like or mount on some plywood.

Assuming the new 6x0x form factor design is successful, I would like to
adopt this form factor for other N8VEM boards to provide better and more
functionally complete peripherals.  Probably the next step would be to
redesign the N8 to use the new form factor although it still remains to be
seen if and how this works.

We already have a notional schematic and PCB layout so the next step is to
get some prototype boards.  I can get four (4) prototype PCBs from Advanced
Circuits for $150 plus shipping.  There are some experienced builders
willing to do the build and test phase so we can move ahead with the
project.  However, we need to raise some funds to order the prototype PCBs
so I am seeking some contributions to a “6x0x prototype PCBs fund”. 

If you would like to contribute please send a PayPal to LYNCHAJ-***@public.gmane.org
with “6x0x prototype PCBs fund” in the subject.  If you choose to donate you
are not obligated to build and test although if you want to volunteer that
would be great.  If we don’t raise the funds after a reasonable amount of
time I will issue refunds.

Please keep in mind though the initial prototype boards will almost
certainly not work as intended and will require extensive debugging, cuts
and jumpers, dead-bugs, and all sorts of heinous, grisly PCB circuit
modifications.  As a result the initial build and test team has to be small
and limited to the most experienced builders.  If you recall the N8 and
uPD7220 GDC build and test phases then you’ll know what I am referring too!

If you have any questions or comments please feel free to ask.  Thanks and
have a nice day!  Andrew Lynch