Explain the meaning of the following terms: ROM - Read Only Memory This type of memory is also called non-volatile memory, it holds information, which is created when the chip is manufactured, and the memory is burnt into the chip. This means that the memory is preserved when the power is disconnected from the chip. ROM is used to store the "programs" required to start the computer and provider the machine with the information needed to use the different pieces of internal architecture. Normally ROM contains the required information to perform certain tasks required by the computer system, these tasks include displaying a welcome message, setting lights to their default state in Slot machines for example, repositioning motors to their start positions within industrial machinery. RAM - Random Access Memory This type of memory is called volatile memory. The "state" of the memory is only preserved when the chip is supplied with power. When the power is lost the internal gates in the memory “switches” all lose their states and default back to 0 or off. RAM is used to hold information about the current status of the machine, and also the programs and drivers the user requires. For example, RAM is the area where information is held until it is "saved" to disk by an application, such as this document in Word, or the position and angles of robotic arms used to paint car bodywork in the manufacturing process. Basically, anything, which may be varied, is normally held in RAM. Disk Drive A Disk drive is a device which allows the computer to access information, Disk drives maybe internal or external, the main types are Hard Drives, CD/DVD Drives, Zip Drives, all these allow mass storage of information. The main drive in a computer is called a "Hard Drive" the Drive is made up of a central spindle with a number of disks, the disks hold information on the magnetic media which coats the disks. An arm with a "Head" moves over the surface, without making contact with the surface, the head detects the state of the magnetic data and feeds the information to the computer. The disk drive contains all the required software and machinery for moving the head and spinning the disk, the head sends the detected readings, such as North and South magnetic readings or Light reflectivity in laser equipment such as CD’s and DVD’s, this reading is decoded by the software within the disk drive equipment, and reported back to the computer system through a data bus, normally a series of wires connected to the drive. Floppy Disk This type of drive is basically the same as a "hard" drive, where information is held on magnetic disks, however, the actual disk is held within a plastic case, which is removable from the drive and portable. Information may be recorded and removed from the disk and other disks used in the drive. Disks need to be formatted so the computer knows how many tracks and sectors there are available for storing data. Mother Board This is an internal part of the computer system. It holds all of the computers "Architecture"; this is the electronic bits such as the Data Bus, where the data flows between the devices. Some motherboards contain built in Soundcards and modems. The motherboard also contains "slots" where devices can be connected to the computer, such as Keyboard, Mouse, Monitor, External modems, Disk Drives and graphic cards etc. The motherboard is the main component of the computer system, it contains the CPU (Central Processing Unit), and the memory, both RAM and ROM, with these components, the power supply is connected to the board as well as all the other devices, information flows from one component on the mother board to another part of the board. The whole basis of a computer system where information is requested and retrieved is performed by the motherboard. Bit and Byte These terms refer to how information is stored and grouped together inside the system. The simplest form of memory storage is a Bit, a bit is represented as either "Binary" 0 or 1, this is because memory is basically an electronic switch or gate, when the switch is in the "Off" position this is value 0, and when the switch is in the "On" state this implies a 1. A Data bus is a series of wires, or electric circuits, these where originally laid out in groups of 8, this lead to the term Byte, the combinations of values allowed in a byte are 2^8 = 256. Eight bits allow the whole range of symbols and letters commonly used to be stored in one single Byte. Megabyte As stated a bit uses "Binary" 0 or 1, Binary is a numerical system for representing numbers with a base of 2. We use Decimal numbers, which have a range of 10 digits 0-9. The Number 123 Decimal is calculated as (1 * 10 * 10) + (2 * 10) + (3) The Number 101 in Binary is calculated as (1 * 2 * 2) + (0 * 2) + (1) A Byte which is 8 bits allows a maximum of 11111111 (binary) to be stored this evaluates to 255 (decimal) therefore 0 - 255 allows 256 combinations. As computers use Binary as a base for numbers, in general numbers a grouped into measurements of 1000, i.e. 1000grammes = 1Kilo In computers the nearest we can get to a 1000 Using binary is 2^10 1024 bytes = 1Kilobyte (1K). 1Megabyte (1mb) = 1024 * 1024 = 1048576 bytes. 1Gigabyte (1gb) = 1024 * 1024 * 1024 = 1073741824 bytes. A Megabyte is a unit normally used for representing memory 126mb of Ram A Gigabyte is normally used to represent mass storage such as 13gb Disk Drive.
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