A computer consists of many types of memory. There are devices which hold temporary information, some can be programmed, and others store information. Hard disc drives, Floppy drives, CD-ROM and DVD-ROM are used to permanently store huge amount of data. In addition to these external devices, memory is hardwired into the motherboard. BIOS which is a type of ROM or Read only Memory is one such.
BIOS or basic input output system is a memory stored in ROM which is used at the starting stage of the computer. As the name suggests, BIOS contains the essential software which creates the initial link between the input devises like the keypad and the mouse with the output device like the monitor. It creates the bride between the Hard disk containing the operating system with the microprocessor. This process is called ‘Bootstrapping’.
ROM, Read only Memory. This is a type of memory used in a computer to store data which is of static nature or data which is unchangeable. ROM retains information or data even when the power is cut off. The ROM is an integrated chip which can be made only once and hence its design is tedious. However, it becomes quite economical when manufactured in bulk. ROM chip is hardwired and usually does not need change in the lifetime of the computer. There are instances when it gets damaged or corrupted, in which case a hardware professional is required to change replace the ROM. The ROM should have very fast access and its reading cycle should be as less as possible. This is made possible because it has no moving parts (as against a hard disc memory) and therefore has a lesser access time.
RAM, Random access memory is a fast memory device used for storing information while operating the computer. The information remains stored only till power is provided. In a computer, RAM is generally provided in modules which can be inserted and removed as desired. Many operations and arithmetic calculations are executed by the microprocessor. The intermediate results have to be stored in a temporary memory till required again. This data is stored in the RAM. RAM modules should therefore have a significantly higher access time.
Hard disc drive, HDD is a devise to store information and data permanently. The data does not get erased on switching off the electricity. It contains the operating system, application programs like the Microsoft word and Excel, internet applications like internet explorer and Mozilla Firefox. In addition, it also stores vast amount of data files which are created by the applications. A HDD is an external device which can be attached to the mother board. Usually in a personal computer four of them can be attached simultaneously. In advanced server configurations, it is possible to add an array of fifteen or more hard disks in a chain. Usually, a hard disc is permanently attached to the motherboard and cannot be removed and ported. Lately, USB supported hard disc drives have given mobility and portability to hard disc drives. These USB devices can also be made bootable which can be quite handy in some situations.
