Computer Memory (Random Access Memory)Ram consists of computer chips which store information. They are installed in rows called banks of nine on the motherboard. Only 8 chips per row are used So store data while the 9th is used for parity checking Data transfer between the CPU and RAM occurs at the fastest possible rate since it involves no moving parts as do hard and floppy disk drives.Types of RAM

-Dynamic RAM (DRAM) is (he type of memory most often used. It is, “volatile” meaning (hat it will retain data only as long as the computer is turned on. Any loss of power (even a momentary flicker in electricity) and the data in RAM will vanish. When DRAM is used in a system, additional circuitry is required to refresh the information periodically;

- Static RAM (SRAM) is not a very common form of memory because it is expensive. It has the advantage however of being able to retain data with the use of a battery. If a memory system is small static devices are used because of the additional cost of the refreshing circuit in DRAM. The break-even point seems to be about 16K bytes of memory. Memory system containing more than 16K bytes will generally be dynamic, while system;; containing loss memory will be static.

The speed of RAM chips is measured in nanoseconds (nS); one nanosecond equals a billionth of a second. The speed of RAM installed into the computer must match with the computers’ speed. If the improper speeds are used, the overall operation of the computer will be slowed or the entire system may lock up. The following lists the speed of RAM chips needed with each CPU speed.
- 4.77 MHz CPU needs 200 nS RAM chips ”, ” 8 MHz CPU needs 150 nS RAM chips , – 10 MHz CPU needs 120 nS RAM chips
Current Ram Capacities are 128MB, 256 MB, 512mb. and there is now 1 gig RAM.
As much as you can afford, get the highest RAM for your Computer, the higher the better.

Memory Expansion Cards

The requirements for memory keeps going up. Software application programs need more and more memory to operate efficiently, MS-DOS unfortunately has the ability to access 640 K of memory directly. There are however some schemes which have been devised to indirectly get around the memory limits of DOS.

- Expanded. Memory Specifications (EMS) – This was the first scheme to allow computers to use more memory. II was written in 1985 by Lotus, Intel, and Microsoft. ‘

Enhanced Expanded Memory Specifications (EEMS) – This competing and improved standard was created by other some other largo’ computer product manufacturers; namely AST, Quadram and Ashlon-Tate. This standard was better for multitasking applications than EMS.

- Expanded Memory Specification (EMS) 4.0 – All the companies supporting the previous two standard got together and merged the previous standard into yet expanded memory standard called EMS 4.0. This is now the expanded memory standard on which everyone has agreed, It allows for the use of up to 32 megabytes, the use of larger application software and use of multitasking. It works,on all generation of computers as well.