The word "memory" is used to describe an electronic circuit that is able to store data and program instructions as well. Memory can be thought of as a work space for a computer and memory also determines the size and number of programs that can be run in the same time, as well as the amount of data that can be processed.
Based on the speed of memory there are 4 kinds:
A type of memory where acces the fastest speed, the memory contained on cpu / processor.
Data registers, address registers, stack pointer register, Memory Address Registers, I / O Address Register, etc..
Limited memory capacity, high speed memory is more expensive than the existing memory utama.Cache between main memory and the processor registers, order processing functions not directly refer to the main memory so that performance can be improved.
Cache memory is there are 2 kinds:
1. Cache memory is contained on the internal processor, cache memory this type accesnya very high speed, and the price is very mahal.Dapat seen on the processor as P4, P3, AMD-ATHLON etc.. The higher capacity of L1, L2 cache memory, the more expensive and faster processor.
2. Cache memory located outside the processor, which is located on the Mother board, this type of memory access speed is very high, although not as fast as the first type of cache memory (which is on the internal processor). The greater the capacity, the more expensive and faster. Capacity of cache memory is 256 kb, 512 kb, 1 Mb, 2 Mb etc.
This memory is used to store data and programs.
Main types of memory:
-Random Access Memory (RAM)
Random Access Memory (RAM), or also called memory, is a computer equipment (hardware / hardware). Ram is one type of data storage device on a computer or other electronic media (PDA. HP, Notebook, Netbook, etc.) which are temporary. It means that when the computer is turned off, then all instructions or data that has been dsimpan in this ram will be lost. SoRam function is to store temporary instructions for removing it from the computer to the output device.There are several types of RAM in the market today are SRAM, EDORAM, SDRAM, DDRAM, RDRAM, etc. VGRAM.
The following Types of memory that has been circulating:

RAM FPM (Fast Page Mode DRAM)

DRAM memory is a model that is very old (SIM development results ancestors RAM RAM) was found at about 1987 .., RAM is still a lot of shortcomings in terms of speed and the ability to accommodate the data, has a 30 foot pin (brass plate number of memory / slot ), can only be run on the Maximum clock 16 Mhz to 66 Mhz with access speed of approximately 50 ns, which is why pemoresesan access data in memory to be very slow, in the encounter on the computer intel 386.
2. EDO RAM (Extended-Data-Out RAM)

EDO-RAM has the functions such as RAM, but this kind of work has a very high capacity and fast in reading and transferring data. EDO-RAM is a form of SIMM (Single Inline Memory Module). It was found in 1995 pegembangan results of FPM RAM, clocked 33-66 mhz on the road and has a 72 pin foot. It's just that there are additional new technologies incorporated in the chip Chace very helpful in processing the data access time of the RAM, EDO RAM to increase the speed of almost 40-50% of the FPM RAM than its predecessor, is no longer used in current use in the computer intel 486.

3. SD RAM (Synchronous Dynamic RAM)

SDRAM is a memory that can assess the data or information faster than EDO-RAM. Form is DIMM SDRAM (Dual Inline Memory Module). Is a model / type of my most enduring memory for the duration of the RAM on the market and was replaced by a substitute for the kind of memory that baru.memori emerged from early 1996 until about 2001 still used by the platfrom of mainboard issued at the time . Of computers Pentium I, II, III, until the beginning of the emergence of a Pentium IV computer. RAM is the way to 100-133 mhz FSB clock, 168 pin and wear electric power of 3.3 volts, has the ability to mensingkronkan clock contained in the memory by the processor clock, this causes the computer system to run balanced in other words the time pemoresesan data more quickly and efficiently.
4.RD RAM (Rambus Dynamic RAM)

RDRAM is a high-speed memory, digunaan to support the Pentium processors use a slot 4.tipe RDRAM RIMM, which is similar to the slot SDRAM.RAM developed by company Rambus has characteristics capable of running at clock FSB 800/1066, 184-pin, and using power power at 2.5 volts, the main difference compared to DDR RAM memoy lies in how this process the data. on RD RAM if the data in the DDR RAM Serial while processing data in parallel, RD RAM was the first to use Dual Channel technology, despite having good performance RD RAM is rarely used anymore because the price is expensive .. Early exit in 1999.
5. DDR RAM (Double Data Rate RAM)

DDR SDRAM is the next generation of SDRAM memory type, which has the ability to two times faster than SDRAM. DigunakanDDR SDRAM memory slot has a pin number more than SDRAM, the memory characteristics have the FSB 266/333/400 MHz clock, 184-pin, 2.5 Volt, in use on a Pentium IV computer berplatfrom up or the like is a result of the regeneration of SD RAM, has a 2x speed according to the length of SDRAM Double Data Rate 1 this is due to the clock capable of carrying / access the number of data bits in the appeal as much as 2 SD RAM is only able to accommodate the data of 1 bit per clocknya, this memory made to compete RD RAM memory which has been first out and now has become market leader The King of Memory. The development of memory is also quite fast now it is up to the fifth generation (DDR, DDRII, DDRIII, IV DDR, DDR V).
-Read Only Memory
Read Only Memory (ROM) is a set of chips that contains part of the operating system which is required at the time the computer starts. ROM is also known as firmware. ROM can not be written or changed its content by the user. ROM storage media belonging to the non-volatile nature. The use of this example is a ROM for storage of BIOS (Basic Input-Output System) made by the manufacturer. BIOS is a very critical part of an operating system, which functions to tell the computer how to access the disk drive. When the computer is turned on, RAM is empty and the instructions on the ROM BIOS is what is used by the CPU to find the disk drive that contains the main files in the operating system. Computer and then move the files into RAM and then run it.
There are 4 types of ROM, namely:
programmable read only memory. Rom that we can return to the program notes may only be one change after it can no longer deprogram.Chip PROM chip is a blank in which the program can be written to it by using a special apparatus. PROM chip can be programmed once and usually used by plants as a control device in its products.
Re progamable ROM.Merupakan development of PROM version where we can make changes repeatedly as desired.
Erasable programmable read only memory. Similar to PROM EPROM, but the program can be removed and a new program that can be written into it by using a special equipment that uses ultraviolet light. EPROM is used for controlling devices, such as robots and so on.
Electronic erasable programmable read only memory. EEPROM chips can be reprogrammed using a special electric impulses. They do not need to be repealed or amended.
Secondary memory is additional memory that is used to store data or programs. Example: hard drives, floppy disks, diskettes, flashdish, etc..