Hi All,
for those who arnt up to speed on this board, the backplane itself
(no atx board attached) is a separate board from the ATX board. the kit is 2
(two) boards. one 18-slot backplane board and one ATX PSU board. the backplane
board is a "normal" 18-slot active terminated S-100 bus board. The
backplane will wire straight up to your +16, -16, +8 and GND power inputs of
your S-100 compliant power supply and work as a normal S100 backplane would,
you can use it without the ATX board. For all intents and purposes you can
throw the ATX board at the cat and forget about it. the backplane board is very
similar in design to any other active terminated S-100 bus board. the ATX PSU
board however is a separate board that has a 24 pin ATX connector on it
(accepting the 20 or 24 pin ATX plug) it has a terminal block output that you
'could' wire up to the input of your S-100 board backplane IF you 1. did not
have the need for exactly +16 -16 and +8V. 2. wanted to wire up +5 onto your
+8v rail if you ran cards without onboard voltage regulators, 3. could wire up
the +12,V -12V, +12V to the "+16, -16, +8v".. please note on
this wiring up +12V to the +8V rail is not recommended as your voltage regulators
will run hot (it would be best to take the +12v and put it into a high current
DC-DC converter to give you +8v). you have the ability to choose what you put
on your power rails. It also works prity nice to use your salvaged ATX supply
for a lab PSU. the ATX PSU (we could call it a sub-card) has: +12v, +5v, +3.3v,
GND & -12v output on its terminal block.
The ATX board uses a
small PIC microcontroller to act as the "debounce" switch (on/off) as
its about expensive as the amount of 7400 series devices i would have used to
put on the board to do the same job. i realize this may cause some "Ahhhhh
Errrrrr" for some users.. but the source code or .HEX file, and programmed
devices can be supplied if needed.
a point of
discussion is the thickness of the board, i realize the current N8VEM 8 slot
board uses 3.2mm thickness to make the board very rigid, my biggest concern
about this is the ability of the user to use standard S100 connectors that have
about a 3mm lead coming out the bottom after the plastic standoff. i would like
users to be able to utilize the S100 connectors that some may have been
collecting for the last few months. i have added extra mounting holes along the
board so there is a mounting hole on either side of every two connectors.
currently the PCB house i have sent the design (and use regularly) said 2.0mm
was available but not 2.4mm or 3.2mm. current pricing for a 2.0mm board is
approximately $31ea for a 10pcs run. i doubt i would like to try and make the
board any smaller at this point. but an idea is always to pull off the ATXPSU
board and have that manufactured separately if there is not a big demand for
it.
i will be taking
pre-orders of an initial batch of boards with a Red soldermask once the design
has been completed and vetted by the "test group". (or Andrew might
like to run it though his Mnufacturer?) this thread is a show of interest and
discussion on possible errors and general development. Questions and Comments
WELCOME! :-)
http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder¶m=18%20Slot%20S100%20Backplane
Kind Regards,
Antony