SS2 COMPUTER DATA CONVERSION

COMPUTER DATA CONVERSION

REGISTERS

Registers are temporary storage area for instructions or data. They are not a part of memory; rather they are special additional storage locations that offer the advantage of

speed. It works under the direction of the control unit to accept, hold, and transfer instructions or data and perform arithmetic or logical comparisons at high speed. Most operations are done on the register; the processor cant directly perform arithmetic in memory. For example, if you want to add 1 to a memory address, the processor will normally do this by loading the initial value from memory into a register, adding 1 to the register, and then saving the value back to memory.

The width (in bits) of the processors register determines how much data it can compute at a time. This is sometimes used to label the processors size.

ADDRESS

A memory address is an identifier for a memory location, at which a computer program or a hardware device can store data and later retrieve it. 

In modern byte  addressable computers, each address identifies a single byte of storage; data too large to be stored in a single byte may reside in multiple bytes occupying a sequence of consecutive addresses. 

Some microprocessors were designed to be word  addressable, so that the addressable storage unit was a larger one than a byte. The efficiency of addressing of memory depends on the size of the address bus.

In a computer program, an absolute address, (sometimes called an explicit address or specific address), is a memory address that uniquely identifies a location in memory. 

BUS

A bus, in computing is a set of physical connections (cables, printed circuits etc.) which can be shared by multiple hardware components in order to communicate with one another.

A bus is a communication system that transfers data between components inside a computer or between computers. This expression covers all related hardware components (wires, optical fibres) including communication protocols. 

A bus is a transmission path on which signals are dropped off or picked up at every device attached to the line.

The purpose of bus is to reduce the number of pathways needed for communication between the components, by carrying out all communications over a single data channel.

CHARACTERISTICS OF BUS

1. A bus is characterized by the amount of information that can be transmitted at once.

2. Width is used to refer to the number of bits that a bus can transmit at once.

3. Frequency is the speed of the bus, which is the number of data packets sent or received per second. It is expressed in Hertz (Hz).

4. Cycle refers to each time data is sent or received.

5. Transfer speed is the amount of data which it can transport per unit of time. It is the product of width and frequency.

TYPES OF BUS

The lines or pins of a bus are of three types:

Address Bus - the components that passes memory addresses to one another over the address bus.

Control Bus - used to send out signals to coordinate and manage the activities of the motherboard components.

Data Bus - transfers between peripherals, memory and the CPU. Obviously, the data bus can be a very busy pathway.

PRIMARY BUS

There are two buses within a computer;

Internal bus (also known as a front-side bus (FSB)) allows the processor to communicate with the systems central memory (RAM).

Expansion bus (also known as input/output bus) allows various motherboard components to communicate with one another. However, it is mainly used to add new devices using what are called expansion slots connected to the input/output.

Functions of Buses in Computers

The functions of buses can be summarized as below:

1. Data sharing  All types of buses found on a computer must be able to transfer data between the computer peripherals connected to it.

The data is transferred in in either serial or parallel, which allows the exchange of 1, 2, 4 or even 8 bytes of data at a time. (A byte is a group of 8 bits). Buses are classified depending on how many bits they can move at the same time, which means that we have 8-bit, 16-bit, 32-bit or even 64-bit buses.

2. Addressing  A bus has address lines, which match those of the processor. This allows data to be sent to or from specific memory locations.

3. Power A bus supplies power to various peripherals that are connected to it.

4. Timing The bus provides a system clock signal to synchronize the peripherals attached to it with the rest of the system.

The expansion bus facilitates the easy connection of additional components and devices on a computer, for example, the addition of a TV card or sound card.