Computer Architecture The circuitry in a computer which controls the manipulation of data is called the central processing unit, or CAP]. In the machines of the mid-twentieth century, Cups were large units comprised of perhaps several racks of electronic circuitry that reflected the significance of the unit. However, technology has shrunk these devices drastically. The Cups found in today’s desktop computers and notebooks are packaged as small flat squares (approximately two inches by two inches) whose neglecting pins plug into a socket mounted on the machine’s main circuit board (called the motherboard).
In smartness, mint-notebooks, and other Mobile Internet Devices (MID), Cups are around half the size of a postage stamp. Due to their small size, these processors are called microprocessors. • CPU Basics A CPU consists of three parts: the arithmetic/logic unit, which contains the circuitry that performs operations on data (such as addition and subtraction); the control unit, which contains the circuitry for coordinating the machine’s activities; and the register nit, which contains data storage cells (similar to main memory cells), called registers, that are used for temporary storage of information within the CAP].
Some of the registers within the register unit are considered general-purpose registers whereas others are special-purpose registers. General-purpose registers serve as temporary holding places for data being manipulated by the CAP]. These registers hold the inputs to the arithmetic/logic unit’s circuitry and provide storage space for results produced by that unit.
To perform an operation on data stored in main memory, the control unit transfers the data from memory into the general-purpose registers, informs the arithmetic/logic unit which registers hold the data, activates the appropriate circuitry within the arithmetic/logic unit, and tells the arithmetic/logic unit which register should receive the result. For the purpose of transferring bit patterns, a machine’s CPU and main memory are connected by a collection of wires called a bus.
Through this bus, the CPU extracts (reads) data from main memory by supplying the dress of the pertinent memory cell along with an electronic signal telling the memory circuitry that it is supposed to retrieve the data in the indicated cell. • The Stored-program Concept Early computers were not known for their flexibility�the steps that each device executed were built into the control unit as a part of the machine. To gain more flexibility, the early electronic computers were designed so that the CPU could be conveniently rewired.
This flexibility was accomplished by means of a pegboard arrangement similar to old telephone switchboards in which the ends of Jumper wires were plugged into holes. The idea of storing a computer’s program in its main memory is called the stored- program concept and has become the standard approach used todayвЂ?so standard, in fact, that it seems obvious. What made it difficult originally was that everyone thought of programs and data as different entities: Data were stored in memory; programs were part of the CAP]. Reference: http://colossal . Com/homework-help/computer-science-homework-help/
