RAM Memory Basics:

1. FPM Memory is 16 bit or 32 bit memory.
2. EDO RAM is 64bit memory.
3. SDRAM is 64 bit memory.
4. FPM RAM works on PCs up through 486 systems.
5. EDO RAM will work in Pentiums and later models.
6. SDRAM is on DIMM chips. They are 168-pin modules.
7. SDRAM works on Pentium II systems with DIMM slots, but not on the older machines with 30 and 72-pin SIMM slots.

1. Memory Upgrades:

   Memory upgrades will be limited by the type of memory banks or slots you have available on your memory, maybe even by the BIOS, and the arrangement of the banks of your memory slots. You will have to read your "User's Manual" carefully.

   1. IF you have a 486 Intel based system, you will have to use FPM RAM for an upgrade. You can purchase 30 pin SIMMs with up to 4 MB per SIMM, or 72 pin SIMMs with 16 MB per SIMM.
   2. Parity Memory (FPM RAM w/4bits for parity) should work in Pentium based PCs, if you get the proper XX-pin SIMMs.
   3. If you have 30-pin SIMM slots on your motherboard, you will have to get 30-pin SIMMs (or a new motherboard). If you have 72-pin SIMMs, you will have to get 72-pin SIMMs.
   4. If you have "parity" memory, you will need to purchase "parity" memory. If you have non-parity memory, purchase non-parity memory.
   5. If you have open SIMM slots, you can fill up the open slots with the same type of memory you currently have. It might not be enough.
   6. If you have no SIMM slots, or too few SIMM slots to reach your goal in total memory, you may have to replace most of your current memory with higher capacity SIMM chips (4, 8, or more MB SIMMs).
   7. If you have propriatory memory, you will probably have to buy from the company or manufacturer.
   8. If you have FMP RAM, you will have to purchase FPM RAM.
   9. If you have FPM or EDO RAM, you probably won't be able to go to the new high speed SDRAM.
   10. If you have only SIMM slots, you won't be able to upgrade to DIMM chips.
   11. READ CAREFULLY BEFORE YOU BUY, OR YOU MAY HAVE TO RETURN YOUR PURCHASE.

2. CONSTRAINTS:

   If you have an older machine, manufactured before 1993, you probably have Fast Page Mode RAM. You will have to add Fast Page Mode RAM if upgrading. You cannot mix FPM, EDO, and SDRAM memories, because the memory banks will normally allow one type, and also the BIOS will not recognize newer types than what it was originally set up to see.