What is RAM?
The computer RAM memory stands for Random Access Memory. It means that it is a type of memory card or chip for computers wherein its memory cells are accessed arbitrarily. When the computer is in use, data are being stored and retrieved in a random manner. RAM is commonly used to perform tasks while the computer is turned on wherein it allows all the information to be accesses in any order at any location in an equivalent manner. The reverse occurs with Serial Access Memory, or SAM. With SAM, data are stored in a sequential manner.

How does RAM work?
RAM functions as a short-term memory storage only since it loses data once the computer is turned off. The long-term memory storage is located at the computer’s hard disk. When the computer is once again turned on, the hard disk would load the data to the RAM wherein the user can easily retrieve any file he wanted from any location.

A type of memory chip is called a DRAM which means Dynamic Random Access Memory. DRAM is an integrated circuit in which memory cells are made of millions of pairs of tiny transistors and capacitors. Each pair becomes a memory cell, which is represented as a single bit of data.

What is DDR SDRAM?
The latest DRAM type in use nowadays is referred to as DDR SDRAM or Double Data Rate Synchronous Dynamic Random Access Memory. DDR SDRAM interface makes transfer rates higher since there is a stricter timing control with the clock signals and the electrical data. This type of integrated circuit is very powerful and works twice as much as compared to its older version, the Single Data Rate (SDR) SDRAM. For instance, a PC133 SDRAM can run at a speed of 133 Mhz. With a 133 Mhz DDR, it can reach a speed of 266 Mhz or 133 Mhz x 2. Another example is when there are 64 bits of data that are being transferred at one time, the DDR SDRAM will transfer that data at twice its memory bus clock rate multiplied to the number of bits to be transferred and divided by bits/byte number that can be transferred per second. Therefore, if the DDR SDRAM interface has a bus frequency of 100 MHz, it will transfer 64 bits of data at a maximum transfer rate of 1600 MB/s. That is 100MHz x 2 = 200 x 64bits = 12800 bits/8 bits per byte per second = 1600 MB/s. MB/s stands for megabyte per second. Take note that 8 bits represent each byte of data. Bit rate is also known as data transfer rate, which is the unit used in telecommunications. It refers to the average number of bits or characters passing per unit of time between equipment in a data transmission system.

What is DIMM? DIMM is an acronym that stands for Dual Inline Memory Module. So, what does it look like? A dual inline memory module varies in the number of memory components (the memory components are usually black in color) attached to a printed circuit board (the board is usually green in color). You will see gold pins or what we called the “integrated circuits” from the front and the back of the DIMM, they are not connected in any way to each other. If you will count the number of pins, it usually has ninety-four (94) pins in front and another ninety-four (94) pins at the back for a total of one hundred eighty-four (184) pins.

The DIMM which again stands for Dual Inline Memory Module is usually used in desktops and servers. There are actually four (4) types of DIMM, these are:

1. The 100 pin DIMM is normally used for printer SDRAM or Synchronous Dynamic Random Access Memory);
2. The 168 pin DIMM is used for SDR SDRAM or Single Data Rate Synchronous Dynamic Random Access Memory);
3. The 184 pin DIMM is used for DDR SDRAM or Double Data Rate Synchronous Dynamic Random Access Memory; and
4. The 240 pin DIMM is used for Fully Buffered DIMM DRAM or Dual Inline Memory Module Dynamic Random Access Memory, which has the capacity to increase the speed, density and reliability of memory systems.

The 100 pin DIMM waits first for a clock signal before it responds to control inputs because of the synchronous interface it is using. The 168 pin DIMM is seldom used in servers or workstations but nevertheless it has the ability to acknowledge one command and shift one word of data for each clock cycle. The 184 pin DIMM, on the other hand, has the capacity to shift data to the connection twice than the SDR SDRAM (Single Data Rate Synchronous Dynamic Random Access Memory). While the 240 pin DIMM has the ability to raise its speed, reliability and density of its memory. The 240 pin DIMM is usually utilized for high speed memory of any working data.

So as time goes by, inventions are updated especially when it comes to computers more specifically when it comes to kinds of memory. The common memory nowadays as we all know is the DIMM as enumerated above. If you are going to change your mother board and wanted to purchase a new one, you need to likewise decide on whether to purchase a new memory or upgrade the same because it happens that you purchase a new board but the same is not compatible with your existing memory. If you have decided to change your memory as well into a lot more efficient like DIMM, you are now faced with the choice of which of the four (4) kinds of DIMM are you going to purchase. Think about it, in the end it is still your choice which one to use and be compatible with your mother board. Think wisely!