Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!sdd.hp.com!caen!math.lsa.umich.edu!sharkey!aucis!zds-oem!easton
From: easton@zds-oem.UUCP (Jeff Easton)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: SIMM Modules
Message-ID: <1101@zds-oem.UUCP>
Date: 16 May 91 12:58:17 GMT
References: <1701@giaea.gi.oz> <mmm.1221@reaper.Chi.IL.US> <1098@zds-oem.UUCP> <07915.AA07915@babylon.rmt.sub.org>
Organization: Zenith Data Systems, OEM Engineering
Lines: 60

In article <07915.AA07915@babylon.rmt.sub.org> cbmvax.commodore.com!cbmehq!babylon!rbabel (Ralph Babel) writes:
>In article <1098@zds-oem.UUCP>, easton@zds-oem.UUCP (Jeff
>Easton) writes:

>32-bit-wide SIMMs in a 30-pin socket? This would indeed be a
>nice trick! :-) No, it's really 64 pins. (And I really like
>the new SIMM sockets used by GVP! Well, I probably have to
>change SIMMs more often than most people.)

  Its hard to tell how big they are from the pictures in the Amiga
World Ads...

>I've been told that they designed their own 32-bit-wide SIMM
>because: (a) there was no accepted standard at that time;

  Not true.

>and (b) they wanted to include some "sense" pins to get rid
>of almost all of those memory configuration jumpers. The new

  The "standard" also uses 4 pins for determining size.

>"all-in-one" accelerator board, for example, has only two
>memory jumpers left, mainly to decide whether to configure
>the SIMMs as Zorro-II or "Extended" (beyond $00ffffff) RAM.
>
>I don't know whether or not this is true. I don't know how
>much of a standard the JEDECx32 SIMMs are or if there are
>other "standards" around. I don't know if those JEDEC SIMMs
>also include pins that could be used by the RAM controller
>hardware to automatically sense the presence of a SIMM.

  Yes, see above.

>So please correct me if I'm wrong.

  The Jedec parts are 72 pins, seperated into two sets of 36, on .050"
spacings.  I'd be willing to bet a accelerator card that the GVP SIMM's
are also 72 pins.  Anybody can go out and design a small PCB for a SIMM
with any odd number of pins they like.  The hard part is convincing the 
connector companies like AMP to custom tool a odd size SIMM socket for
your low volume product.

  We've been using x36 SIMM's in our products for 2 years, so they have
been around for a while.  Admittedly we use page mode parts where 
the GVP uses nibble mode but it shouldnt be that hard to find a 
memory supplier that a) is in the SIMM business and b) manufactures
nibble mode DRAM's.

  I would be interested in seeing the pinout of the GVP parts if you
have the info and care to type it in.

>Ralph


        Jeff Easton               Zenith Data Systems
     // Systems Engineer 
   \X/  easton%zds-oem@caspian.cs.andrews.edu
	easton@andrews.edu	
   What?  Preemptive Multitasking in only 256K of RAM?  :^)  :^)