nstalling RAM

Installing memory chips is a relatively simple matter in most Macs. When you purchase them they usually come with directions and sometimes with the correct tools. If you have a compact Mac you need to look in that section on taking the computer apart. Most other macs are simpler as the case come apart more easily.
When installing the SIMM boards (small circuit boards with memory chips on it) you should take great care not to damage the SIMM or the connector it goes into. Older Macs particularly are prone to damage as they have plastic clips that hold them in place. These clips lock the SIMM in and if broken off the SIMM will not hold in properly and the socket will have to be replaced; not an easy job as it has multiple solder joints.

RAM Chips

RAM (random access memory) chips are volatile storage; they hold information only while power is applied to them.  They come in a wide array of sizes and configurations and are sold in banks on a small circuit board called SIMMS. If you are about to purchase them let the person selling them to you figure out what is needed. All you have to do is tell them the Mac model you have and the present amount of memory you have installed. (Command-i from the finder will call up a get info box to let you know your memory configuration). The array of simm configurations requires a wall chart to cover the various Macs that are and have bee manufactured.
Simms do come with one distinction...the speed.  RAM speed is measured in nanoseconds (nsec), which are billionths of a second. The factory-installed RAM in a stock Plus or SE runs at 150 nsec. These are fairly slow simms but since these computers are not fast then more expensive faster simms are not necessary. Other faster computers may have 120 nsec., 80 nsec., or faster simms. Just get the right ones.
Installing simms is pretty straightforward but different on many of the Mac models. Most simm purchases come with good directions and sometimes even a video. You should have little problems.

Scrolling down you will see simplified diagrams for the placement of RAM for most of the Macintosh Computers. Afterward will be a description of the RAM needed for those machines. If you are at all adept with this type of thing you should be able to do a RAM installation on your own. Be sure to wear a static strap (Radio Shack) on your wrist to protect your computer!

SIMM Locations
back, front  - the front or back of the board. typically the back of the logic board is the end with the connectors for your printer, keyboard and such.

RAM or DRAM - the type of memory chip used in the computer. When you order it you'll get the right one.

Banks and slots - simply a way to indicate which connector to put SIMMS into first. This is important in some Macs.

VRAM - another type of memory that helps the screen (particularly color and large color screens keep up with the speed of the processor. Without it you would have to wait longer for the pictures to build on the screen. Typically the more the better but if you don't have heavily graphic programs that you need fast updates for, like CAD (computer aided design) programs then what you have that came with your computer may be enough.

 

Memory, Mac by Mac

Compact Macs
With compact Macs be sure to either fill or not fill a row.
Place the larges SIMMS in the first row or bank.
There must be the same SIMMS in each row or socket. You cannot mix them up.

Mac Plus
Maximum RAM: 4mb
Fill SIMM bank A with the highest value SIMMs first
A sizing resistor must be cut if filled with 1 meg SIMMS (R8)

SE
Maximum RAM: 4mb
Load sockets with highest value SIMMS in sockets 1 and 2 first.
Older models: a sizing resistor (see Mac Plus) must be clipped.
Later models: a jumper clip must be removed.

SE/30
Maximum RAM: 32mb
Fill sockets in groups of four with the same SIMMS
The SE/30 is not 32 bit clean. I f you want to access more than 8mb of RAM you would need a program callled MODE32 or system 7.1 or greater.

Classic
Maximum RAM: 4mb
Fill sockets of a RAM expansion card with two 1mb SIMMS. The computer already has 1mb on the logic board and the RAM expansion card comes with two sockets and 1mb already soldered in. Total - 4mb.
A memory sizing jumper must be set when adding memory

Classic II
Maximum RAM: 10mb
Fill two sockets with 4mb SIMMS

Color Classic
Maximum RAM: 10mb addressable although 12mb physically possible.
Fill two sockets with 4mb SIMMS (there is already 2mb on the logic board)

Modular Macs
Modular Macs are all of those "after" the Classics. Some are really not modular but look so at first glance.

Mac LC
Maximum RAM: 10mb
Two sockets that can hold up to 4mb SIMMS. (12mb possible but only 10 mb addressable, 2mb already on board).
Up to 512mb of VRAM can be added in one VRAM socket.

Mac LCII
Maximum RAM: 10mb
Fill with up to 4mb SIMMS. They must be identical.
There are 2mb on board already and with 10mb that equals 12mb but only 10mb are addressable.
There is one VRAM socket with 256k installed. Up to 512k can be installed.

Mac LCIII
Maximum RAM: 36mb
Fill one SIMM socket with up to 36mb
512k of VRAM on board. 256k SIMM more can be added to the empty socket.

Mac 575
See LCIII

Mac 520
See LCIII

Mac IIsi
Maximum RAM: 17mb
1mb on board, all four SIMM sockets must be filled with the same SIMMS.
There is no separate VRAM

Mac IIcx
Maximum RAM: 32mb
1mb on board and the four empty sockets can be filled with identical SIMMS
There is no separate VRAM.

Mac IIci
Maximum RAM: 32mb
Two models of IIci were made. The most common one requires groups of four sockets to be filled one bank at a time. Fill bank B last.
The least common one requires nine chip SIMMS. You can tell if you have this ci if the parity chip (located at the lower left of chip bank B) is present.

Mac IIfx
Maximum RAM: 32mb
The fx uses a special 64 pin SIMM. Fill with up to eight 4mb SIMMS. These SIMMS are not used in any other Mac.

Mac IIvx
Maximum RAM: 64mb
4mb on the logic board and 4 SIMM sockets can hold 16mb SIMMS.
VRAM is upgradeable to 1mb

Quadra 605
Maximum RAM: 36mb
4mb already on the board with one 72 pin SIMM socket. Use a 16mb or 32mb SIMM
VRAM can be upgraded to 1mb.

Quadra & Centris 650
Maximum RAM: 132mb or 136mb depending on which Centris you have. One has 4mb the other 8mb on the logic board. Thus the maximum RAM is 132mb or 136mb

The Quadra 650 has the 8mb installed and is upgradable to 136mb.

Both computers can have SIMMS installed in any order. You can't use 1mb, 2mb, or 64mb SIMMS.

Quadra & 660AV
Maximum RAM: 68mb
Installationof SIMMS in any order or any connector. 4mb is installed on the logic board. Incompatible with 1mb, 2mb, and 64m SIMMS.
VRAM is on the board with 1mb and can't be expanded any further.

Quadra 700
Maximum RAM: 20mb
Four SIMM sockets that can accept 1mb or 4mb SIMMS. 4mb is already on the logic board.
VRAM six sockets that can hold 2mb max.

Quadra 800
Maximum RAM:136mb
4 sockets that allow installation of any memory configuration in any slots in any order. Incompatible with 1mb, 2mb, and 64mb SIMMS
VRAM, 1mb max.

Quadra 840AV
Maximum RAM: 128mb
4 sockets that allow installation of any memory configuration in any slots in any order. Incompatible with 1mb, 2mb, and 64mb SIMMS
VRAM, 2mb max.

Quadra 900 & 950
Maximum RAM: 64mb
16 SIMM sockets with 4 SIMMS per socket. Each bank must be filled completely with 1mb, 4mb, or 16mb SIMMS.
VRAM: up to 2mb

Power PC 6100/60
Maximum RAM: 72mb
SIMMS must be installed in pairs in each pair ofsockets. 8mb are soldered into the logic board. It will accept 4mb, 8mb, 16mb, and 32mb SIMMS

Power PC 7100/66
Maximum RAM:136mb
SIMMS must be installed in pairs in each pair ofsockets. 8mb are soldered into the logic board. It will accept 4mb, 8mb, 16mb, and 32mb SIMMS

Power PC 8100/80
Maximum RAM: 264mb
SIMMS must be installed in pairs in each pair ofsockets. 8mb are soldered into the logic board. It will accept 4mb, 8mb, 16mb, and 32mb SIMMS