COA Chapter 1

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Computer Architecture and Organization

Computer Architecture•

Attributes of a system visible to the programmer

Have a direct impact on the logical execution of a program

Architectural attributes

Instruction set, number of bits used to represent various data types, I/O mechanisms, techniques for addressing memory

Organizational attributes

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

Computer Organization

​​​​​​​The operational units and their interconnections that realize the architectural specifications

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Structure and Function

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

Structure

The way in which components relate to each other

Function

The operation of individual components as part of the structure

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Function

There are four basic functions that a computer can perform:

Data Processing: Data may take a wide variety of forms and the range of processing requirements is broad

Data Storage: Short-term, Long-term.

Data movement : Input-output - when data received from to delivered to a device

Control: manages the computer’s resources and orchestrates the performance of its functional parts in response to instructions

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Structure

CPU: controls the operation of the computer and performs its data processing functions

Main Memory: Stores data

I/O: moves data between the computer and its external environment

System Interconnection: some mechanism that provides for communication among CPU, main memory, and I/O

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CPU major structural components

Control Unit: Controls the operation of the CPU

Arithmetic and Logic Unit (ALU) : Performs the computer’s data processing function

Registers: Provide storage internal to the CPU

CPU Interconnection: Provides connections among the control unit and ALU and registers

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Multicore Computer Structure

Central processing unit : fetches and executes instructions. Consists of an ALU, a control unit, and registers

Core: May be equivalent in functionality to a CPU on a single-CPU system

Processor : Is the computer component that interprets and executes instructions

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Cache Memory

Multiple layers of memory between the processor and main memory

Is smaller and faster than main memory

Used to speed up memory access by placing in the cache data

A greater performance improvement may be obtained by using multiple levels of cache

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Measures of capacity and speed:

Kilo- (K) = 1 thousand = 103 and 210

Mega- (M) = 1 million = 106 and 220

Giga- (G) = 1 billion = 109 and 230

Tera- (T) = 1 trillion = 1012 and 240

Peta- (P) = 1 quadrillion = 1015 and 250

Exa- (E) = 1 quintillion = 1018 and 260

Zetta- (Z) = 1 sextillion = 1021 and 270

Yotta- (Y) = 1 septillion = 1024 and 280

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An Example System

Computers with large main memory capacity can run larger programs with greater speed than computers having small memories.

RAM is an acronym for random access memory. Random access means that memory contents can be accessed directly if you know its location

Cache is a type of temporary memory that can be accessed faster than RAM.

Serial ports send data as a series of pulses along one or two data lines

Parallel ports send data as a single pulse along at least eight data lines

USB, Universal Serial Bus, is an intelligent serial interface that is self-configuring

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First Generation: Vacuum Tubes

Vacuum tubes were used for digital logic elements and memory

Fundamental design approach was the stored program concept

Attributed to the mathematician John von Neumann

Design began at the Princeton Institute for Advanced Studies

Completed in 1952

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Registers

Memory buffer register: Contains a word to be stored in memory or sent to the I/O unit

Memory address register: Specifies the address in memory of the word to be written from or read into the MBR

instruction register : Contains the 8-bit opcode instruction being executed

Instruction buffer register: Employed to temporarily hold the right-hand instruction from a word in memory

Program counter: Contains the address of the next instruction pair to be fetched from memory

Accumulator and multiplier quotient: Employed to temporarily hold operands and results of ALU operations

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Second Generation: Transistors

Smaller

Cheaper

Dissipates less heat than a vacuum tube

is a solid state device made from silicon

was invented at bell labs in 1947

It was not until the late 1950’s that fully transistorized computers were commercially available

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Second Generation Computers

More complex arithmetic and logic units and control units

The use of high-level programming languages

Appearance of the Digital Equipment Corporation (DEC) in 1957

This began the minicomputer phenomenon that would become so prominent in the third generation

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Third Generation: Integrated Circuits

1958 – the invention of the integrated circuit

Discrete component

Manufacturing process was expensive and cumbersome

Single, self-contained transistor

The two most important members of the third generation were the IBM System/360 and the DEC PDP-8

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Integrated Circuits

Data storage – provided by memory cells

Data processing – provided by gates

Data movement – the paths among components are used to move data from memory to memory and from memory through gates to memory

Control – the paths among components can carry control signals

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IBM System/360

Announced in 1964

Product line was incompatible with older IBM machines

Was the success of the decade and cemented IBM as the overwhelmingly dominant computer vendor

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Microprocessors

The density of elements on processor chips continued to rise

1971 Intel developed 4004

1972 Intel developed 8008

1974 Intel developed 8080

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Embedded Systems

The use of electronics and software within a produc

Billions of computer systems are produced each year that are embedded within larger devices

Often embedded systems are tightly coupled to their environment

Constraints such as required speeds of motion, required precision of measurement, and required time durations, dictate the timing of software operations

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Embedded Operating Systems

There are two general approaches to developing an embedded operating system (OS):

Take an existing OS and adapt it for the embedded application

Design and implement an OS intended solely for embedded use

Application Processors versus Dedicated Processors

Application processors

Defined by the processor’s ability to execute complex operating systems

General-purpose in nature

An example is the smartphone – the embedded system is designed to support numerous apps and perform a wide variety of functions

Dedicated processor

Is dedicated to one or a small number of specific tasks required by the host device

Because such an embedded system is dedicated to a specific task or tasks, the processor and associated components can be engineered to reduce size and cost

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Deeply Embedded Systems

Subset of embedded systems

Uses a microcontroller rather than a microprocessor

Has no interaction with a user

Typically have extreme resource constraints in terms of memory, processor size, time, and power consumption