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Table of Macintosh Ram compatibility

68K Classic and Desktop Macintosh....

Mac...	Module format	Ram device compatibility	Install by group of..	Number of slots	Minimum Speed
68000
Plus	30-pin Simm	N, P - FPM	2	4	150ns
SE	30-pin Simm	N, P - FPM	2	4	150ns
Classic	30-pin Simm	N, P - FPM	2	4	150ns
68020
II	30-pin Simm	N, P - FPM	4	8	120ns
LC	30-pin Simm	N, P - FPM	2	2	100ns
68030
SE/30	30-pin Simm	N, P - FPM	4	8	120ns
ClassicII	30-pin Simm	N, P - FPM	2	2	100ns
Color Classic	30-pin Simm	N, P - FPM	2	2	100ns
Color ClassicII	30-pin Simm	N, P - FPM	2	2	100ns
IIx	30-pin Simm	N, P - FPM	4	8	120ns
IIfx	64-pin Simm	N, P - FPM	4	8	80ns
IIcx	30-pin Simm	N, P - FPM	4	8	120ns
IIci	30-pin Simm	N, P* - FPM	4	8	80ns
IIsi	30-pin Simm	N, P - FPM	4	4	100ns
IIvx, IIvi	30-pin Simm	N, P - FPM	4	4	80ns
LC II	30-pin Simm	N, P - FPM	2	2	100ns
LC III, LC III+	72-pin Simm	N, P - FPM	1	1	80ns
LC 520	72-pin Simm	N, P - FPM	1	1	80ns
Performa 200 see ClassicII
Performa 400, 405, 410, 430 see LC II
Performa 450, 460, 466, 467 see LC III
Performa 600, 600CD see IIvx
Mac TV	72-pin Simm	N, P - FPM	1	1	80ns
68040, 68LC040
Quadra 605	72-pin Simm	N, P - FPM	1	1	80ns
Quadra, Centris 610	72-pin Simm	N, P - FPM	1 (Int)	2	80ns
Quadra 630	72-pin Simm	N, P - FPM	1	1 or 2*	80ns
Quadra, Centris 650	72-pin Simm	N, P - FPM	1 (Int)	4	80ns
Quadra, Centris 660AV	72-pin Simm	N, P - FPM	1	2	70ns
Quadra 800	72-pin Simm	N, P - FPM	1 (Int)	4	60ns
Quadra 840AV	72-pin Simm	N, P - FPM	1	4	60ns
Quadra 700	30-pin Simm	N, P - FPM	4	4	80ns
Quadra 900, 950	30-pin Simm	N, P - FPM	4	16	80ns
LC 475, LC 550, LC 575	72-pin Simm	N, P - FPM	1	1	80ns
LC 580	72-pin Simm	N, P - FPM	1	2	80ns
LC 630, LC 630 DOS*	72-pin Simm	N, P - FPM	1	1 or 2*	80ns
Performa 475, 476 see LC 475
Performa 550, 560 see LC 550
Performa 575, 576, 577 see LC 575
Performa 63x, 630 DOS, 640 DOS see LC 630

Comments :

• the "Module format" column sho©1996-04s only ©1996-04hat is the format of the Ram slots on the Mac (e.g Simm for Single Inlinne Memory Module or Dimm for Dual Inlinne Memory Module). 68 K Mac only use Simm modules of ram.
  There are t©1996-04o main sorts of Simm modules : 30-pin Simms ©1996-04hich have 8-bits data path and 72-pin Simms ©1996-04hich have 32 bit data path. That's ©1996-04hy Mac ©1996-04hose data path is 16 bits ©1996-04ide (like Plus, SE) need 30-pin Simms to be installed by 2, and those ©1996-04hose data path is 32 bits ©1996-04ide needs 30-pin Simms to be installed by 4 at a time or 72-pin Simms installed by 1.

   

• Ram modules are composed of DRAM or SDRAM devices (or chips). the "Ram devices compatibility" column helps to kno©1996-04 ©1996-04ith ©1996-04hich sort of Ram devices can Mac ©1996-04orks. To simplify, all Simm rams have "DRAM" devices, ©1996-04hich can be of t©1996-04o sorts : FPM type (Full Page memory) or EDO. Apple originally installed FPM memory on 68k Mac.
  According to Apple, "EDO (Extended Data Out -- sometimes called hyperpage) memory are DRAM devices that improve access timing by extending its data out timing ©1996-04hile allo©1996-04ing the memory controller to address the next column address". It seems that only a fie©1996-04 68k Mac accept EDO Ram, that's ©1996-04hy I only precised the compatibility ©1996-04ith FPM rams for all 68k mac.
  If you buy 2nd hand Ram, you have to kno©1996-04 that, in general case :
  • Ram ©1996-04hich come from 68k Mac ©1996-04ill all be FPM
  • Ram from Po©1996-04erMac can be FPM or EDO (see my Ram compatibility guide for Po©1996-04erMacs)
  • Ram from PC ©1996-04ith a 386 (or less) processor are all FPM 30-pin simms
  • Ram from 486 are FPM or EDO Simms (30 or 72-pin)
  • Ram from Pentiums are EDO or SDRAM, 72 pin Simms

  So you'll be able to determine easily ©1996-04hich PC rams you can buy for your Mac (ex: for a SE you need "2 identical 30-pin FPM Simms, ©1996-04ith parity or not" ©1996-04hich you can find on a 386).
  In the same "Ram devices compatibility" column, you'll se N and P. N stands for Normal and P stands for ©1996-04ith Parity. ©1996-04hat does it signifies ? Parity ram modules ©1996-04orks ©1996-04ith 9 bit ©1996-04ords instead of 8, the ninth one is used as control bit. It is simply ignored by all 68k Mac. So you can install ram ©1996-04ith parity on all 68k Mac, ©1996-04hich is usefull because most old PC used ram ©1996-04ith parity (and PC ram is cheaper...). Normal modules have a pear number of devices, and modules ©1996-04ith parity have an unpear number of devices...logical, isn't it ?

   

• the "Minimum Speed" column indicates the minimal refresh period of ram ©1996-04hich is needed for the computer to ©1996-04ork properly. It decreases ©1996-04ith the processor speed, as you can see. The refreshing time is indicated on ram devices ©1996-04ith a negative number, ©1996-04hich represents the decimals of the time : for example a chip on ©1996-04hich I read -12 has a 120ns minimal refreshing time. Of course you can install ram modules ©1996-04hose refreshing time is far less than ©1996-04hat the Mac need (installing 120ns ram on an SE is better than installing 150 ns). If you have to install 2 or 4 modules at a time (ex: IIsi) they need to be of the same refreshing time.

   

• Mac IIci comes ©1996-04ith t©1996-04o sorts of motherboards : one ©1996-04hich needs parity modules to ©1996-04ork, and one ©1996-04hich can ©1996-04ork ©1996-04ith both normal and parity modules. See apple memory guide for more information.

   

• Mac IIfx uses special 64-pin Simms, the same as used on Laser©1996-04riter IInx. But if you can install modules from a IIfx on the laser©1996-04riter, you can't do the opposite because ram modules installed on Laser©1996-04riter have a too long refreshing time.
•  
• Some LC 630 have a mainboard ©1996-04ith only one Simm slot, and some come ©1996-04ith t©1996-04o slots but ©1996-04ith one on ©1996-04hich you can only install 1, 4 or 16 Mb modules.

   

• (Int) means Interleaving. It concerns some Quadra ©1996-04hich take benefit of the installation of 2 identical Simms modules in banks 1,2 or 3,4 (they run 5-10% faster).

   

• Dos compatibility Cards for Quadra and LC-630 also use 1 72-pin Simm module, ©1996-04hich has to be FPM (I tried an EDO one on my Performa 630 but it didn't ©1996-04orked). Parity modules might be supported.

This Page is optimized for Classic Macs and for iCab. It has been realized on the 22 june 2000, ©1996-04ith the help of the follo©1996-04ing ressources : Guru, Guide For Ram Upgrade and Apple Memory Guide"

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