e0001 computers in engineering1 the system unit & memory

E0001 Computers in Engineering 1

E0001 Computers in EngineeringE0001 Computers in Engineering

The System Unit & MemoryThe System Unit & Memory


ReadingsReadings

““Computers in Your Future” - Chapter 2Computers in Your Future” - Chapter 2 1997 - chapter 21997 - chapter 2 1998 - 2A & 2B1998 - 2A & 2B ““Using Computers A Gateway to Using Computers A Gateway to

Information” 1995 - Chapter 4 & 6Information” 1995 - Chapter 4 & 6 1997 - chapters 3 and 51997 - chapters 3 and 5 1999 - chapter 31999 - chapter 3


This Lecture:This Lecture:

the system unitthe system unit main memory - RAM, ROMmain memory - RAM, ROM data representation - binary codesdata representation - binary codes error checking - Parityerror checking - Parity


The Binary SystemThe Binary System

Data, instructions are represented Data, instructions are represented electronically with a binary or two-state electronically with a binary or two-state numbering system.numbering system.

three principal codesthree principal codes– ASCIIASCII– EBCDICEBCDIC– UnicodeUnicode


Binary Coding SchemesBinary Coding Schemes ASCIIASCII

– American Standard Code for Information InterchangeAmerican Standard Code for Information Interchange– most widely usedmost widely used– 8 bits = 1 byte8 bits = 1 byte

EBCDICEBCDIC– Extended Binary Coded Decimal Interchange CodeExtended Binary Coded Decimal Interchange Code– industry standard for large computersindustry standard for large computers

UnicodeUnicode– sixteen bit codesixteen bit code– designed to support languages like Chinese & Japanesedesigned to support languages like Chinese & Japanese


Error CheckingError Checking

parityparity– oddodd– eveneven

Find out the difference between odd and Find out the difference between odd and even parity! - Exam Hint!!!!!even parity! - Exam Hint!!!!!


The System UnitThe System Unit connected to input and output devices, and connected to input and output devices, and

secondary storagesecondary storage

contains:-contains:- motherboardmotherboard central processing unit - CPUcentral processing unit - CPU main memorymain memory system clocksystem clock expansion slots and boardsexpansion slots and boards bus linesbus lines portsports


The MotherboardThe Motherboard

containscontains– CPUCPU– some memory chipssome memory chips– expansion slotsexpansion slots


The CPU - central processing The CPU - central processing unitunit part of the computer that executes part of the computer that executes

instructionsinstructions sometimes called sometimes called processorprocessor is on a single electronic component - is on a single electronic component -

microprocessor chipmicroprocessor chip has two componentshas two components

– the control unitthe control unit– arithmetic logic unit - ALUarithmetic logic unit - ALU


The Control UnitThe Control Unit

tells the rest of the computer how to carry tells the rest of the computer how to carry out the programs instructionsout the programs instructions

directs (controls) movement between directs (controls) movement between memory and the ALUmemory and the ALU

controls signals between CPU and controls signals between CPU and input/output devicesinput/output devices

machine cycle - fetching, decoding, machine cycle - fetching, decoding, executing, storingexecuting, storing


The Arithmetic Logic UnitThe Arithmetic Logic Unit

performs two operationsperforms two operations– arithmeticarithmetic– logiclogic

arithmetic operations - fundamental math arithmetic operations - fundamental math operations operations – additions, subtraction, multiplication, divisionadditions, subtraction, multiplication, division

logic operations - consist of comparisonslogic operations - consist of comparisons– =, <, >=, <, >


Microprocessor ChipsMicroprocessor Chips

CISC chips - complex instruction set computerCISC chips - complex instruction set computer– most widely used chip design - hence runs a large most widely used chip design - hence runs a large

number of existing programsnumber of existing programs– e.g. Intels Pentiume.g. Intels Pentium

RISC chips - reduced instruction set computerRISC chips - reduced instruction set computer– design is simpler, faster, less costlydesign is simpler, faster, less costly– e.g. PowerPC, Alpha chipe.g. PowerPC, Alpha chip


Memory - RAMMemory - RAM

temporarilytemporarily holds data, program holds data, program instructions, and informationinstructions, and information

also know as RAM, primary storage, also know as RAM, primary storage, internal storage, or main memoryinternal storage, or main memory

RAM - Random Access MemoryRAM - Random Access Memory– volatilevolatile– destructive write process; nondestructive readdestructive write process; nondestructive read– memory has four types memory has four types


RAMRAM

four typesfour types– conventional memoryconventional memory

• consists of the first 640K of RAMconsists of the first 640K of RAM

• used by DOS and application programsused by DOS and application programs

– upper memoryupper memory• located between 640K and 1Mlocated between 640K and 1M

• used by DOS - info about hardware; also used by DOS - info about hardware; also application programsapplication programs


– extended memoryextended memory• directly accessible memory above 1Mdirectly accessible memory above 1M

• available on most microprocessorsavailable on most microprocessors

• not accessed by all programsnot accessed by all programs

– expanded memoryexpanded memory• special ‘island’ of memory up to 32MB that exists special ‘island’ of memory up to 32MB that exists

outside the DOS 640K limitoutside the DOS 640K limit

• intended to help older micros that cannot directly intended to help older micros that cannot directly access memory over 1Maccess memory over 1M

cache memorycache memory– high speed RAMhigh speed RAM– stores most frequently used instructionsstores most frequently used instructions– sits between CPU and Main memorysits between CPU and Main memory


cache memorycache memory


ROMROM

Read Only MemoryRead Only Memory non-volatilenon-volatile contents cannot be changed by the usercontents cannot be changed by the user typically contain instructions for detailed typically contain instructions for detailed

computer operations e.g. start the computer, computer operations e.g. start the computer, put characters on the screen, give keyboard put characters on the screen, give keyboard keys special featureskeys special features

two typestwo types


ROM typesROM types

PROM - programmable read only memoryPROM - programmable read only memory– once programmed cannot be changedonce programmed cannot be changed

EPROM - erasable programmable read only EPROM - erasable programmable read only memorymemory– PROM chip that can be erased by UV lightPROM chip that can be erased by UV light– new instructions can then be writtennew instructions can then be written– EEPROM - electrically erasableEEPROM - electrically erasable


System ClockSystem Clock

controls the speed of operations with in the controls the speed of operations with in the computercomputer

expressed in MHz - mega hertz - one expressed in MHz - mega hertz - one million cycles per secondmillion cycles per second

faster clock speed - faster computer faster clock speed - faster computer operatesoperates


Expansion SlotsExpansion Slots memory expansion slotsmemory expansion slots

– several additional RAM chips increase the memory several additional RAM chips increase the memory capacitycapacity

Network adaptor cardsNetwork adaptor cards– used to connect the computer to one or more used to connect the computer to one or more

computerscomputers– forms a communication networkforms a communication network

Small computer system interface - Small computer system interface - “scuzzy”cards“scuzzy”cards

PC cardsPC cards


bus linesbus lines


Bus LinesBus Lines

connects parts of the CPU to each otherconnects parts of the CPU to each other links CPU to important hardwarelinks CPU to important hardware four principal bus linesfour principal bus lines

– Industry Standard Architecture (ISA)Industry Standard Architecture (ISA)– Micro Channel Architecture (MCA)Micro Channel Architecture (MCA)– Extended Industry Standard Architecture Extended Industry Standard Architecture

(EISA)(EISA)– Peripheral Connect Interconnect (PCI)Peripheral Connect Interconnect (PCI)


PortsPorts

connecting socket on the outside of the connecting socket on the outside of the system unitsystem unit

parallel portsparallel ports serial ports serial ports

e0001 computers in engineering1 the system unit & memory

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