Please use precaution in handling your memory modules

ESD or electrostatic  Static Discharge may damage them and your system

Use a an ESD worksation or ground yourself with a wrist strap

or keep contact with a metallic non painted part of the chassis.

The most common architecture  of memory is :

PC100 AND PC 133 SIMMS (SINGLE IN LINE MEMORY MODULE) 

Newer laptops  use either DDR or DDR2 SDRAM SO- DIMMS ( DOUBLE DATA RATE - SMALL OUTLINE DUAL  INLINE

MEMORY MODULE)  the most common standard is: 

asyncronous,

unbeffered,

 non parity,

non ECC ( error correction)

72 pins (FPM EDO RAM),

144 pins  (FPM, EDO SDRAM)

and 200 PINS (DDR SDRAM).

Newer laptops , including MACS are running  DDR SDRAM PC 2100, PC 2700  or  PC3200,  200 pins. ( with exclusion of Picture Books that use Micro So-Dimm)

DDR SDRAM is installed  in single modules not necessarily in pair.

With SDRAM you can mix different sizes like 512 and 256 MB for a total of 768,.

If you mix 2 speeds like PC 2100 and 2700 ( backward compatible) you'll get the slower speed .

The Module has a notch that needs to be aligned with a tiny prong in the slot, hold the module at 35 dgrees angle and insert it pushing inward and down, you should hear the clips clicking, when horizontal give a final check/push with 2 or more fingers.

The memory bank is ususally at the bottom under a door that is marked with a symbol  that looks like a 2 sided comb.

Some IBM, Sony and Mac machines have the empty slot in the inside, underneath the keyboard, The Mac IBOOK has the slot underneath the Air Port Card, which is itself underneath the keyboard.

IBM are very good at showing online how to remove/insert the memory.

If your system becomes instable after adding a new memory module, chances are

the module is incompatible or defective.

If your system does not detect the new memory and you made sure it is compatible  contact

your memory manufaturer or re-seller..

Do not forget to protect your valuable laptop and memory by grounding yourself prior to touching the memory, never ever  remove or insert

memory while the machine is turned on, hold the chip by its edges and avoid touching the pins.

And please wisely unplug the AC and remove the battery prior to opening the memory door.