1. Pentium Computers require memory to be installed in pairs. For example, if you want to add 16mb, you will need to buy two 8mb SIMMS.

2. 30 or 72 Pin? If your SIMM measures 3 1/2" in length, its a 30 pin, if it's 4 1/2" it is a 72 pin.

3. Parity or Non-parity? Look at your existing memory and count the number of chips on the SIMM. If it has 2, 4, 8 or 16 chips it is non-parity. If it has 3, 9, 12 or 24 chips, it is Parity. Parity memory has extra bits that detect memory errors.

386 and early 486 motherboards take 30 pin simms. To upgrade to 16 mb you have to buy four 4x9 30 pin simms. Approx price is $20 per chip, for a total of $80. These 30 pin simms are obsolete and cannot be used on newer systems, when you upgrade.

Newer 486 systems use 72 pin parity and non-parity. These systems vary with installing 1, 2 or 4 chips at a time. The chips cost: Parity: 4x36 16mb $42 Non-Parity: 4x32 16mb $30, 2x32 8mb $25

Newer Pentiums Take EDO 4x32 16mb $25.

• ULN Fair Prices on Memory
• Pc Progress Very Good Prices on Memory
• SuperByte Ocean Motherboards
• Superior Ocean Motherboards
• MicroShack - Panasonic CDR, Cases
• Bunta, Rhino 15+ MotherBoards

Identifying PC100 compliant DIMMs 10/8/99

Identifying the size and speed rating of an unknown memory module can be difficult if it is not labeled clearly, and it is easy to confuse a PC66 spec module with a PC100, resulting in an unreliable system and lots of woe. Firstly, PC66 spec memory is rated to perform at least to 66MHz, and possibly higher. This is fine if your system is running a processor with a 60 or 66MHz bus speed, such as a Pentium II 266Mhz. With the Intel BX chipset motherboards and Pentium II 400MHz processors, though, the bus speed rises to 100MHz. The memory modules used with these systems must adhere to very strict timing requirements to perform reliably, and this is where the PC100 specification comes in.

Specifically, the module must have an SPD-EEPROM and the chips must be labeled 10nS or less. The SPD-EEPROM (serial presence detect) is a small chip about 4 millimeters long with eight pins, usually mounted at one end of the module. This EEPROM can be read by the motherboard when booting so that it knows what type of ram is installed. The speed rating of the chips isn’t very helpful though, as some PC66 memory is marked as 10nS also. The first step is to find the manufacturer of the chips using the table below. For example, a chip marked HY5116100A was manufactured by Hyundai.

Memory Manufacturers: 

Finally, note whether the chip or module is PC133, PC100 or PC66Fujitsu
 

Hitachi
 

Hyundai
 

IBM
 

LGS
 

Micron
 

Nanya Technologies
 

Samsung
 

Siemens
 

Texas Instruments