SIMMs and DIMMs & READ ONLY MEMORY (ROM)

SIMMs and DIMMs

The capacity of RAM in a computer affect computer's power. More capacity of RAM means the computer can use larger an more powerful programms and those programms can access bigger data files. More RAM can make computer run faster. The computer does not necessarily have to loa an entire programme into memory to run it, but the more of the programme it can fit into memory, the faster the programme will run. For example, a PC with 8 MB of RAM is capable of running Microsoft Windows even though the programme actually occupies about 40 MB on the disk storage space. When you run Windows, the programme does not to load all the files of windows into memory to run properly. It load only the essential parts into memory. When the computer needs to access other parts of the programme on the disk, it can unload nonessential part from RAM back to the hard disk and load the programme code or data it needs. However if your PC has larger RAM, windows will run faster because CPU will need to unload programme instructions between RAM and the hard disk less often.

Instead of (dual in line Pin) DIP package, today's computers use SIMMs (Single in-line Memory modules) and plug it in your computer easily. SIMMs and DIMMs provide large memory capacity but require very little space. They are available in many several configurations and in variety of speed. Each SIMMs or DIMMs can hold 4 MB to 128 MB of RAM. You can expand RAM capacity of your computer by plugging in more SIMMs or SIMMs chips.

When you purchase additional memory for your computer, you must make sure that the memory modules you purchase are the current type, and sould match with the configuration and speed for your computer system.

READ ONLY MEMORY (ROM)

A special type of internal memory contained in the computers is the Read Only Memory (ROM). This is a permanent of the computer designed by the manufacturers of the computers and cannot be altered by the programmer. The contents of ROM, a non-volatile technology, are hard wired (i.e., designed into the logic of the memory chip) by the manufacturer and can be read only. It is used to store the instructions required to control the basic input outpur operations of a computer whenever the computer system is turned on when you turn on a microcomputer system, a programme in ROM that resides in it automatically readies the computer system for use and displays the initial display-screen prompt. ROM is a semiconductor chip programmed at the time of its manufacture and is not reprogrammable by the user. Programmes sotred in ROM are called firmware. ROM is a non-volatile memory, i.e. the contents of this type of memory are not lost when the computer is turned off.

A variation of ROM sis programmable read-only memory (PROM). FROM is ROM into which you, the user, can load read-only programms and data. Some microcomputer software packages, such as electronic spreadsheets, are available as PROM units as well as on interchangeable disks. Generally, once a programme is loaded to PROM, it is sel-dom, if ever, changed. ROM and PROM are used in a variety of capacities within a computer system.