John, the usual 3x boards for me. Thank you! Fabio Battaglia On May 31, 2015 10:53 PM, "monahanz" <[email protected]> wrote:
> 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* > <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:- > > 1. 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. > 2. I wanted to hand lay down broad power traces to all the boards IC’s > for more even power distribution. > 3. 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. > 4. 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). > 5. 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. > 6. 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. > 7. 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. > 8. 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. > 9. 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 [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- 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 [email protected]. For more options, visit https://groups.google.com/d/optout.
