[comp.sys.mac] SIMM pinout

kent@lloyd.camex.uucp (Kent Borg) (09/13/88)

Does somebody out there know the pinout of a Mac compatible SIMM?

Thanks.

Kent Borg
kent@lloyd.uucp
or
hscfvax!lloyd!kent

edc@aeras.UUCP (news guest account) (09/14/88)

In article <190@lloyd.camex.uucp> kent@lloyd.camex.uucp (Kent Borg) writes:
>Does somebody out there know the pinout of a Mac compatible SIMM?
>
>Thanks.
>
>Kent Borg
>kent@lloyd.uucp
>or
>hscfvax!lloyd!kent

Please post the responses!  I wanna kludge me some cheap memory too!!

-edc-

kent@lloyd.camex.uucp (Kent Borg) (09/16/88)

In article <274@aeras.UUCP> edc@aeras.UUCP (news guest account) writes:
>In article <190@lloyd.camex.uucp> kent@lloyd.camex.uucp (Kent Borg) writes:
>>Does somebody out there know the pinout of a Mac compatible SIMM?
>
>Please post the responses!  I wanna kludge me some cheap memory too!!
>-edc-

Turns out the answer was from in-house.  From a Toshiba data book,
page A-191 the THM91000S/L-10/12, 1M bit x 1 bit:

(Looking down on component side of the SIMM, connector on the left.)

VCC	1
*CAS	2
DQ0	3
A0	4
A1	5
DQ1	6
A2	7
A3	8
VSS	9
DQ2	10
A4	11
A5	12
DQ3	13
A6	14
A7	15
DQ4	16
A8	17
A9	18
N.C.	19
DQ5	20
*W	21
VSS	22
DQ6	23
N.C.	24
DQ7	25
Q8  (DQ8??)	26
*RAS	27
*CAS8	28
D8	29
VCC	30

Good luck!

Kent Borg
kent@lloyd.uucp
or
hscfvax!lloyd!kent

ching@pepsi.amd.com (Mike Ching) (03/29/89)

I am trying to make a memory expansion board using SIMMs but can't find
the pin definition of the 30 pin connector. I suppose I could buy the
module and ohm it out but prices seem to be dropping and I'd prefer to
delay the purchase until I've built the motherboard. Any help would be
appreciated.

Thanks in advance,
Mike Ching
ching@lassen.AMD.COM

spraggs@ve7apu.UUCP ( VE7ADE) (03/30/89)

This is the pinout for a 1 Meg SIMM.  I have shown the assignments for
a 9 bit part for completeness.  The ninth chip is missing on a Mac SIMM
so these (*) are NC as well.

A 256k part is NC on A9.  I expect a 4 Meg part puts A10 on pin 19 and a
16 Meg one has A11 on pin 24.

X        ___
X    Vcc CAS DQ1 A0 A1 DQ2 A2 A3 Vss DQ3 A4 A5 DQ4 A6 A7 .. continued in line
X     1                                               15
X  
X                     _                   ___ ___
X .. DQ5 A8 A9 NC DQ6 W Vss DQ7 NC DQ8 Q9 RAS CAS9 D9 Vcc
X    16                                *       *   *  30

Vcc = +5V    Vss = ground  DQ = Data I/O   A = Address
___                            ___
CAS = Column Address Strobe    RAS = Row Address Strobe

Since the Mac + at least does not pull down D9 or CAS9, by 9 SIMMs 
should not be used since these inputs can float through the mid voltage
region.  When this happens excessive current flows, causing over heating
and possibly enough noise to corrupt data.

John Spraggs