F21 test board SIMM connector

["John Griessen" <john_g@xxxxxxxxxx>]

Here's a possible for a DRAM connector.  Are there DRAM's
available now in this form?  They call it
Small Outline Single In­Line Memory Module (SIMM),
but they also call it
Mini Memory Module (M3), Surface Mount (DIMM).

Surface mount makes the PC board simpler!
As I read the spec below, you have three simm module equivalents
located in a stack laying flat on your PC board if you lay out
one simm module directly on the PC board.  Otherwise, you buy
and plug in a double sided simm  in each connector.  So for F21,
using 256K X 4 modules to get 20 bits requires 5 modules, 2 per connector =
3 connectors

See:     http://connect.amp.com/107-8.html




New from AMP is the miniature M3 socket designed to accept the Small Outline
Single In­Line Memory
Module (SIMM). The board space used by the M3 socket is only half that taken
by standard SIMM sockets.

In addition to saving space on the motherboard, the right angle design of
the socket stands only 5.5 mm
high, taking full advantage of the low profile Thin Small Outline Package
(TSOP). This allows one layer of
TSOPs to be mounted on the motherboard and a double­sided module (3.54 mm
nominal) with two layers
of TSOPs over the motherboard.

The socket is for surface mount applications and comes in a 72­position
configuration. The mating face
contacts are on staggered dual row .050 [1.27] centers, while surface mount
tails are on single row .025
[0.64] centers.

A keying feature helps prevent module damage sometimes caused by
inadvertently inserting 3.5 V modules
into 5.0V systems.
Performance Characteristics

 Termination Resistance
 (Dry Circuit):
                         30 milliohms max: (initial)
 Dielectric Withstanding
 Voltage:
                         250 VAC
 Insulation Resistance:
                         250 megohms min. (initial)
 Operating Temperature:
                         ­55°C to +85°C
 Durability:
                         25 cycles min.


Material and Finish

Housing ­­ Liquid Crystal Polymer (LCP), UL 94V­0
Contacts ­­ Phosphor bronze with gold or tin plating in contact area and
tin­lead plating on surface mount
tail