I
would like to now introduce what will probably be the final version of our very
reliable S100 16MB Static RAM board.
It’s
called the V5 16MB Static RAM S100 board. See here:-
http://s100computers.com/My%20System%20Pages/16M%20RAM%20Board/16MG%20RAM%20Board.htm#A_Third_Prototype_16MB_Static_RAM_Board
(Bottom
of the page).
This
board has the following additional features:-
-
I
did not want to change the basic RAM board circuit. It has proven itself time
and again to be very reliable with any CPU board I could throw at it. Common
easy to obtain 74LSxx chips are used throughout.
-
I wanted to hand lay down broad power traces to all the boards
IC’s for more even power distribution.
-
I
have inserted a trace “Keep out Area” on the front of the board so there is no
danger of the 5V and 3.3V regulator heat sinks touching a critical trace
beneath.
-
I added two 22V10
GALs to replace a number of 74LSxx chips. This greatly simplifies the board and
somewhat speeds up the RAM access times.
I realize not everybody is familiar with GAL’s. For those people who cannot program
GALs and beginners ,I will supply
the pre-programmed Lattice 22V10 GALs. The PALASM code is provided on the web
page. These GAL’s are fairly
common (Jameco #39159 for the 15ns variety).
-
I have added a wait
state circuit (0 - 8 I/O wait states) to accommodate very fast S100 boards
such as our 80386 and 80486 boards.
-
People should be
able to simply switch IC’s from the old board to this new one. Two new GAL ICs
is the only major change.
-
While the board is really built to meet the 16MB addressing range
of the IEEE-696 bus, I have added jumper options so the board can be used in
older systems like an Altair or IMSAI which only use a 16 bit address
bus. Altair/IMASAI RAM write
protect/unprotect can also be implemented on this board.
-
The
board can accommodate EITHER the dual Mezzanine RAM boards described above
(V6.0c), for 16MB of static RAM,
or 8MB by soldering the 4 SMD
CY62167DV30 static RAM chips directly on the board or 16M, by soldering
4 of the newer SMD AS6C3216 (4M X
8bit) static RAM chips on the board.
-
Last but least, I
relabeled much of the Silk Screen to be more relevant. For example placing IC
numbers above their pin locations etc.
Anyway I
will do a group order for a batch of these V5 bare boards.
Please let me know ASAP if you would like one or more bare boards. They will run
somewhere between $14 - $16 each + shipping.
It’s best to send me
an e-mail direct (monahan AT vitasoft DOT org).
John
You received this message because you
are subscribed to the Google Groups "N8VEM-S100" group.
To unsubscribe from
this group and stop receiving emails from it, send an email to
.
.