Computer Organization and Architecture: Chapter 1 - Introduction

Function - 4 basic functions

A computer can perform four basic functions: ● Data processing ● Data storage ● Data movement control

CPU - Major Structural Components

Control Unit Arthmetic and logic unit (ALU) Registers CPU interconnection

Control Unit

Controls the operation of the CPU and hence the computer

Central Processing Unit (CPU)

Controls the operation of the computer and performs its data processing functions; often simply referred to as processor.

Store Data

Even if the computer is processing data on the fly (i.e., data come in and get processed, and the results go out immediately), the computer must temporarily store at least those pieces of data that are being worked on at any given moment. Thus, there is at least a short-term data storage function. Equally important, the computer performs a long-term data storage function. Files of data are stored on the computer for subsequent retrieval and update.

Architectual attributes include:

Instructional sets, number of bits used to represent various data types, I/O mechansims, techniques for adressing memory

I/O

Moves data between the computer and its external environment.

arthmetic/logic unit (ALU)

Performs the computers data processing fucntions.

Registers

Provides storage internal to the CPU

Hierarchical system

Set of interrelated subsystems Hierarchical nature of complex systems is essential to both their design and their description Designer need only deal with a particular level of the system at a time Concerned with structure and function at each level

system interconnection

Some mechanism that provides for communication among CPU, main memory, and I/O. A common example of system interconnection is by means of a system bus, consisting of a number of conducting wires to which all the other components attach.

CPU interconnection

Some mechanism that provides for communication among the control unit, ALU, and registers

Computer Architecture

-Attributes of a system visible to the programmer -Have a direct impact on the logical execution of a program

Four Main Structural Components of The Computer

CPU Main memory I/O System Interconnection

top-down processing

Evidence from a number of fields suggests that the top-down approach is the clearest and most effective. We begin with the major components of a computer, describing their structure and function, and proceed to successively lower layers of the hierarchy. The remainder of this section provides a very brief overview of this plan of attack.

Organizational attributes include:

Hardware details transparent to the programmer, control signals, interfaces between the computer and peripherals, memory technology used

The Computers Interaction

The computer interacts in some fashion with its external environment. In general, all of its linkages to the external environment can be classified as peripheral devices or communication lines. We will have something to say about both types of linkages.

Move data

The computer's operating environment consists of devices that serve as either sources or destinations of data. When data are received from or delivered to a device that is directly connected to the computer, the process is known as input- output (I/O), and the device is referred to as a peripheral. When data are moved over longer distances, to or from a remote device, the process is known as data communications.

Processing Data

The data may take a wide variety of forms, and the range of processing requirements is broad. However, we shall see that there are only a few fundamental methods or types of data processing.

Function

The operation of individual components as part of the structure

Computer Organization

The operational units and their interconnections that realize the architectural specifications

Structure

The way in which components relate to each other

Control

Ultimately, this control is exercised by the individual(s) who provides the computer with instructions. Within the computer, a control unit manages the computer's resources and orchestrates the performance of its functional parts in response to those instructions.

IBM System 370 Architecture

Was introduced in 1970 Included a number of models Could upgrade to a more expensive, faster model without having to abandon original software New models are introduced with improved technology, but retain the same architecture so that the customer's software investment is protected Architecture has survived to this day as the architecture of IBM's mainframe product line

Main Memory

stores data