[oc] Modular FPGA board

[John Dalton <johnd@southern-poro.com>]

Hi all,

I'm looking at building a modular FPGA board.
It will hopefully suitable for home construction,
but at the same time be suitable for processing
signals with bandwidths of at least 100MHz.

The idea is to build a basic motherboard with
FPGA, power supplies, programming and a programmable
oscillator (with maybe a second FPGA and a PCI connector).

Instead of peripherals, it will have a whole bunch of 72
pin SIMM sockets on it.  Peripherals can then be built as
modules and plugged in.  SIMMs have the advantage of
1) being cheap
2) having the potential to go fast (after all, they build 133MHz memory
modules)
3) Not incurring the cost of a socket for each module.
4) Using SMT, a lot can be crammed on a SIMM.

A list of possible peripherals might include:
- video or audio ADCs
- video or audio DACs
- Dynamic RAM (use off the shelf?)
- Static RAM
- Comms - Ethernet, firewire, RS232, PC parallel, USB, ...
- Auxiliary processors (eg DSP)
- More logic
- More SIMM connectors
- etc.

Is anyone aware if such a thing already exists?  After coming
up with this idea, I did a web search and located SIMMstick
(http://www.simmstick.com).  This is a similar idea for micro
controllers,
using 30 pin SIMMs.  As far as I can see, nothing similar exists
for FPGAs.


More questions:
1) Standard SIMMs use 1.27mm thick PCB.  Is it possible
to fit 1.6mm PCB into a 72 pin SIMM?  1.6mm PCB
is much easier to get.

2) Are 72 pin SIMMs still widely available around the world,
or have they been superseded by DIMMs?  (I would like to
keep to SIMMs, as it is difficult to align contacts on both
sides of a home built board.)

Regards
John Dalton