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RE: [N8VEM-S100:988] 512MB DRAM / S-100 Card

Mike, I think we are forming a good game plan.  I will work with Andrew in drawing up the main 80386 CPU board and an "over the top" Static RAM board set of schematics. 

Is there any way you would have time to take a first pass at the 512MB DRAM S-100 board schematic.  Andrew is a real expert in hammering the schematics into shape for an actual prototype board layout/order.  If you could take a first pass at a schematic that would be fantastic. I don't know how much time and interest you have for this,  if not a  lot I would take it from there and coordinate comments suggestions etc. as we go along.   If you have more time that would be truly fantastic. The three board set would be really fantastic and allow many of us to play with software/hardware for a really serious 32 bit CPU in a clear hardware protected mode environment of our own choosing.

Anybody else want to get involved?


John Monahan Ph.D
e-mail: mon...@vitasoft.org
Text:    mon...@txt.att.net

-----Original Message-----
From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of mike
Sent: Tuesday, July 17, 2012 6:05 AM
To: n8vem...@googlegroups.com
Subject: [N8VEM-S100:988] 512MB DRAM / S-100 Card

Hash: SHA1

So to arrive at a 512MB DRAM S-100 card with over-the-top memory bus, using the parts we've been discussing, you end up with 8 x 72-pin SIMMs and 4 x 132-pin PQFP packages, a hand full of bus-glue chips, a few dozen caps, and power supply.

The SIMM array would take up about half of the area of an S-100 card, accounting for some wiggle room to run tracks around.

I think the way to go would be to split the SIMMS into two groups of 4 (bank A and B), and I would see lining up the two banks horizontally side-by-side and pushing those down toward the bottom of the card since there won't be much going on down there except for the power supply coming in. So you have the bottom of the card pretty much fully occupied by the SIMMs.

That would leave the top half of the card free and clear where you should be able to fit the four 132 pin PQFP packages comfortably either on the back or front and still have space left for bus logic, which should be pretty minimal, a hand full of buffers I'm thinking.

If we went surface mount on the bus logic, we could mount those on opposite sides from the memory controllers if space constraints require it.

The long and short is that I believe it can all fit comfortably on one
S-100 board with a little bit of creativity.

- --Mike

On 07/17/2012 03:21 AM, mike wrote:
> So a 512MB DRAM card built around this chip would look like this;
> 4 V96BMC chips, 8 sticks of 64MB 72-pin SIMMs (I think the 72 pin 
> simms are looking like the most likely to be compatible with this 
> arrangement).

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