Memory is where your computer stores data when it is in use. Commonly, this memory is called RAM, OR random access memory. There are many types of RAM chips. When power is lost, all the data on RAM chip is lost. RAM can be used for cache on processor, video card, disk controller, or other functions. However the primary use of RAM is for computer’s primary memory.
Most computers today use form of RAM called a DIMM, or dual inline memory module. So, when most people talk about RAM, they are talking about DRAM (dynamic random access memory); the “dynamic” part just means that the memory constantly needs to refresh and update. The connectors from the DIMM to the slot where it connects are called pins. DIMMs today commonly have 168, 184, or 240 pins.
Mother boards or system boards can have various numbers of DIMM slots. The more DIMMs put in the slots and the higher density of RAM on the DIMMs, the more memory the computer has.
Just like human, RAM can make mistakes and lose data. To check up on RAM there is parity – a numerical calculation. The problem with parity is that it can tell you the RAM made a mistake but not fix it. To resolve this, there is something called as ECC (error checking & correction).
A special type of RAM is cache. Cache is very fast used by CPU. Level 1 cache is built into the CPU. Level 2 cache is outside the CPU, on the system board.
Types of RAM:
- SDRAM: synchronous DRAM, old
- DDR: double data rate, double the speed of SDRAM
- DDR2: double data rate x 2, double the speed of DRAM, that is what is used today
- RDRAM: rambus direct RAM, proprietary SDRAM, used less and less
- SRAM: static RAM, doesn’t require a refresh like SDRAM does, faster then SRAM but more expensive, often used for Cache memory.
- ROM: is read only memory. With ROM, the data is written but cannot be changed. BIOS is stored in ROM.
RAM is packaged in either DIMM, RIMM, SoDIMM, or MicroDIMM.
You can obtain DIMM chips that are single sided or double sided.
Computer storage is measured in bits, bytes, kilobytes, megabytes, gigabytes, and terabytes. A kilobyte is 1024 bits. A megabyte is 1,048, 576 bytes. This system can keep going on and to terabytes, petabytes, exabytes, zettabytes, and yottabytes.