Major Hardware Components of Major Hardware Components of a Computer Systema Computer System

• Central Processing UnitCentral Processing Unit

• Auxiliary StorageAuxiliary Storage

• Input DevicesInput Devices

• Output DevicesOutput Devices

Central Processing UnitCentral Processing Unit• Arithmetic/Logic Unit (ALU): processes data Arithmetic/Logic Unit (ALU): processes data

arithmetically (addition, subtraction, multiplication, arithmetically (addition, subtraction, multiplication, division) or logically (greater than, less than, equal to)division) or logically (greater than, less than, equal to)

• Control Unit: works with the operating system to move Control Unit: works with the operating system to move data between auxiliary storage and main memory; and data between auxiliary storage and main memory; and between main memory and the ALUbetween main memory and the ALU

• Main Memory: contains both program instructions and Main Memory: contains both program instructions and the data that is required.the data that is required.

• A single machine can have multiple CPUs to share A single machine can have multiple CPUs to share processing tasks (co-processors, multiprocessing), but processing tasks (co-processors, multiprocessing), but each CPU can execute only a single task.each CPU can execute only a single task.

Inside the System UnitInside the System Unit• Main component: motherboardMain component: motherboard

– Circuit board that “houses” integrated circuits Circuit board that “houses” integrated circuits (microscopic elements … wires, transistors, (microscopic elements … wires, transistors, etc…) required to make the digital pulse flow etc…) required to make the digital pulse flow inside of the computer. Pulses flow from inside of the computer. Pulses flow from component to component via the “bus”component to component via the “bus”

– Some microcomputers contain a special local Some microcomputers contain a special local bus (VESA or PCI) which increase data transfer bus (VESA or PCI) which increase data transfer rates to the display and/or storage devicesrates to the display and/or storage devices

Motherboard (cont.)Motherboard (cont.)– Attachments to the motherboard include:Attachments to the motherboard include:

• Main Memory: types of main memory include:Main Memory: types of main memory include:– RAM - temporary (includes virtual memory storage). Include RAM RAM - temporary (includes virtual memory storage). Include RAM

cachecache

– ROM - permanentROM - permanent

– CMOS - semipermanent battery poweredCMOS - semipermanent battery powered

» Memory chips attach with either a DIP (dual inline pin - old PCs) Memory chips attach with either a DIP (dual inline pin - old PCs) or as a SIMM (single inline memory module) boardor as a SIMM (single inline memory module) board

– When add main memory, make sure add-on chips are compatibleWhen add main memory, make sure add-on chips are compatible

• Real time clock (current date and time)Real time clock (current date and time)

• Microprocessor or CPU (central processing unit)Microprocessor or CPU (central processing unit)– Control Unit: traffic cop portion of the CPUControl Unit: traffic cop portion of the CPU

– ALU: arithmetic logic unit processes all math and logical operations ALU: arithmetic logic unit processes all math and logical operations performed by the computerperformed by the computer

• Expansion slots/add on boards - allow “cards” that attach Expansion slots/add on boards - allow “cards” that attach various peripheral devices to the motherboardvarious peripheral devices to the motherboard

– monitors, hard drive, internal fax/modem, network cards,etcmonitors, hard drive, internal fax/modem, network cards,etc

– PCMCIA slots: special slots developed for laptops to attach PCMCIA slots: special slots developed for laptops to attach devices and add on RAMdevices and add on RAM

• Expansion devices may provide an external “port” which you Expansion devices may provide an external “port” which you connect a cable to. Device ports will either be from an internal connect a cable to. Device ports will either be from an internal or external bay in the system unit.or external bay in the system unit.

– Serial Port: transmits data one bit at a time (modem)Serial Port: transmits data one bit at a time (modem)

– Parallel Port: transmits 8 bits simultaneously (printers, backup Parallel Port: transmits 8 bits simultaneously (printers, backup devices, etc.)devices, etc.)

– SCSI Port: allows several devices to be chained together and SCSI Port: allows several devices to be chained together and connected through a single SCSI (small computer system connected through a single SCSI (small computer system interface)interface)

– MIDI Port: musical instrument digital interfaceMIDI Port: musical instrument digital interface

MotherboardMotherboard (cont.) (cont.)

Main MemoryMain Memory

• Random Access Memory (RAM):Random Access Memory (RAM): allows data allows data and instructions to be accessed randomly from any and instructions to be accessed randomly from any memory location (address). Primary storage.memory location (address). Primary storage.– Volatile - lost when power is turned offVolatile - lost when power is turned off

• Read Only Memory (ROM): usually contains Read Only Memory (ROM): usually contains programs that help the computer system operate:programs that help the computer system operate:– can only be read: cannot be written to or altered by the can only be read: cannot be written to or altered by the

user (usually)user (usually)

– ROM is not volatileROM is not volatile

Main MemoryMain Memory• Data and instructions are stored as Data and instructions are stored as BITS (binary BITS (binary

digits)digits). Everything from our world is translated . Everything from our world is translated into a computer recognizable format called into a computer recognizable format called binary binary (zeros or ones)(zeros or ones)– The combination of binary digits represents our letters or The combination of binary digits represents our letters or

numbers. One character represented is equal to a numbers. One character represented is equal to a byte.byte.

• Memory capacity is measured in bytes. Today’s Memory capacity is measured in bytes. Today’s most common measurement is most common measurement is megabytesmegabytesKilo = 1,000 (KB) ThousandKilo = 1,000 (KB) ThousandMega = 1,000,000 (MB) MillionMega = 1,000,000 (MB) MillionGiga = 1,000,000,000 (GB) BillionGiga = 1,000,000,000 (GB) Billion

• Bytes are composed using either the Bytes are composed using either the ASCIIASCII coding coding system (7 bits = character) or system (7 bits = character) or EBCDICEBCDIC (8 bits = (8 bits = character)character)

Microprocessor FamiliesMicroprocessor Families

• Intel (IBM) and Motorola (Macintosh Intel (IBM) and Motorola (Macintosh 68000) two main manufacturers68000) two main manufacturers

• Microprocessors are “families” - upward Microprocessors are “families” - upward increases in speed (early SX vs DX chips)increases in speed (early SX vs DX chips)

• Increase in bus capacity indicates a new Increase in bus capacity indicates a new generationgeneration

The Boot ProcessThe Boot Process• When you turn your computer on, the following When you turn your computer on, the following

activities happen:activities happen:– Power is sent to the internal fan and the motherboardPower is sent to the internal fan and the motherboard

– The boot program stored inside of ROM activates The boot program stored inside of ROM activates

– The Power-On Self-Test (POST)runs and tests required The Power-On Self-Test (POST)runs and tests required system componentssystem components

– The operating system/environment is loadedThe operating system/environment is loaded

– Configuration and customization routines are executed Configuration and customization routines are executed which set your computer environmentwhich set your computer environment

Input/Output Peripheral DevicesInput/Output Peripheral Devices

• Badge ReaderBadge Reader• Bar-code ReaderBar-code Reader• Cartridge & cassette drivesCartridge & cassette drives• CD RomCD Rom• Digital cameraDigital camera• Digital tables & scannersDigital tables & scanners• Keyboard, mouse, pensKeyboard, mouse, pens• MICR MICR • VoiceVoice• OCROCR• Touch screenTouch screen

• SASD & DASD drivesSASD & DASD drives• PrintersPrinters

– Page vs line or character Page vs line or character printersprinters

– Impact vs nonimpactImpact vs nonimpact

• PlotterPlotter• RoboticsRobotics• Speech synthesizerSpeech synthesizer• VDTVDT• MicroformsMicroforms

StorageStorageRequired because main memory is limited, expensive Required because main memory is limited, expensive

and volatile.and volatile.

• Sequential Access Storage Devices (SASD): Sequential Access Storage Devices (SASD): data is stored data is stored in sequential order. Retrieval is also sequential.in sequential order. Retrieval is also sequential.– Storage media is magnetic tape.Storage media is magnetic tape.– Supports batch processing environmentSupports batch processing environment– Excellent form of backupExcellent form of backup

• Direct Access Storage Devices (DASD):Direct Access Storage Devices (DASD): data can be stored data can be stored and retrieved randomly.and retrieved randomly.– Storage capacity is referred to as density. How tightly Storage capacity is referred to as density. How tightly

packed data is on the disk.packed data is on the disk.– DASD is required for transaction processing.DASD is required for transaction processing.

• Memory capacity is measured in bytes. Today’s most Memory capacity is measured in bytes. Today’s most common measurement is common measurement is kilobytes,kilobytes, megabytes and gigabits.megabytes and gigabits.

Printer ConsiderationsPrinter Considerations

• Dot matrix - low price & inexpensive to Dot matrix - low price & inexpensive to operate. Lower quality. Impact - can print operate. Lower quality. Impact - can print carbon forms. Color option. Slow.carbon forms. Color option. Slow.

• Ink jet - moderate price & better output. Ink jet - moderate price & better output. Color option. Nonimpact. Quieter.Color option. Nonimpact. Quieter.

• Laserjet - more expensive. Faster. High Laserjet - more expensive. Faster. High quality. Nonimpact.quality. Nonimpact.

Display ConsiderationsDisplay Considerations• Screen size- diagonal measurement from corner to corner. Screen size- diagonal measurement from corner to corner.

Popular sizes are 14”, 15” and 17” Popular sizes are 14”, 15” and 17”• Dot pitch - measure of image clarity. The smaller the dot Dot pitch - measure of image clarity. The smaller the dot

pitch, the crisper the image or resolution.pitch, the crisper the image or resolution.• Video adapters/cards impact image resolution and display Video adapters/cards impact image resolution and display

speed. Today, most monitors are Super VGA (1024 x speed. Today, most monitors are Super VGA (1024 x 768)and use non-interlaced projection technology (flicker)768)and use non-interlaced projection technology (flicker)

• Laptop - liquid crystal display (LCD). Passive matrix vs Laptop - liquid crystal display (LCD). Passive matrix vs active matrix screen (display method which impacts active matrix screen (display method which impacts image quality). Active matrix is much better but more image quality). Active matrix is much better but more expensive and can have problems.expensive and can have problems.

DASDDASD

• Floppy Disk: Floppy Disk: removable DASD. Most common removable DASD. Most common density is 1.44Mb.density is 1.44Mb.

• Hard Disk:Hard Disk: usually don’t remove (but newer usually don’t remove (but newer devices you can). Higher storage capacity than devices you can). Higher storage capacity than floppy disks. Faster access.floppy disks. Faster access.– Winchester drive architecture is not removable.Winchester drive architecture is not removable.– Can be drives that have removable disk platters.Can be drives that have removable disk platters.– Optical disk: CD_ROM (read-only) Erasable optical disk Optical disk: CD_ROM (read-only) Erasable optical disk

is also available. WORM - write once, read many.is also available. WORM - write once, read many.– Flash memory: main memory on a card. Non volatile. Flash memory: main memory on a card. Non volatile.

PCMCIA card.PCMCIA card.

DASD cont.DASD cont.

• All data stored on DASD media is stored in pie-All data stored on DASD media is stored in pie-shaped shaped sectorssectors that determines how much data is that determines how much data is moved into and out of main memory at a time.moved into and out of main memory at a time.

• Virtual storage:Virtual storage: operating system uses hard disk operating system uses hard disk drive as an extension of main memory.drive as an extension of main memory.

• Cache memory:Cache memory: operating system assumes that operating system assumes that most data used by an application is accessed over most data used by an application is accessed over and over again. Cache is a special area in main and over again. Cache is a special area in main memory where such data is put instead of paging memory where such data is put instead of paging it back and forth to DASD.it back and forth to DASD.

DASD contDASD cont

• WORM: write-once, read many. (CD WORM: write-once, read many. (CD ROM). Also have rewriteable CD ROM.ROM). Also have rewriteable CD ROM.

• Floptical Disk: optical storage capacities on Floptical Disk: optical storage capacities on floppy disk.floppy disk.

• DVD: Digital video diskDVD: Digital video disk• Hierarchical Storage: use of many different Hierarchical Storage: use of many different

types of DASD & SASD devices to achieve types of DASD & SASD devices to achieve storage requirements.storage requirements.

Other considerations:Other considerations:• Desktop vs Laptop - expansion slots and Desktop vs Laptop - expansion slots and

capabilitycapability– Port replicators vs docking stationPort replicators vs docking station

– Pointing device. Track ball, touch pad, erase point.Pointing device. Track ball, touch pad, erase point.

– Power management & battery considerations (hot Power management & battery considerations (hot swap)swap)

• Multimedia devices - sound cards, speakers and Multimedia devices - sound cards, speakers and MPC standardsMPC standards

• Bundled softwareBundled software

Common File TypesCommon File Types• Data Files: files of information created when Data Files: files of information created when

people use various types of softwarepeople use various types of software• Executable Files: Types of systems files that are Executable Files: Types of systems files that are

used by the computer to perform certain tasks. used by the computer to perform certain tasks. With some executable files (.exe., .com, .bat) you With some executable files (.exe., .com, .bat) you can initiate the processing while with others the can initiate the processing while with others the computer initiates the process (.dll, .sys, .drv, etc.)computer initiates the process (.dll, .sys, .drv, etc.)

• You and your You and your AUTOEXEC.BATAUTOEXEC.BAT file. file.

Anatomy of a FilenameAnatomy of a Filename

• Rules for creating valid filenames Rules for creating valid filenames (appropriate characters, length of names, (appropriate characters, length of names, etc.) depends on the operating system being etc.) depends on the operating system being used.used.

• Components of a filename consist of:Components of a filename consist of:

C:/foldername/filename.extC:/foldername/filename.extDrive DesignationDrive Designation

Folder/subdirectoryFolder/subdirectorynamename

File name fromFile name fromyouyou

File extensionFile extensionsupplied by thesupplied by the

programprogram

File StorageFile Storage• Logical StorageLogical Storage::

How you perceive that data How you perceive that data is stored on an auxiliary is stored on an auxiliary storage mediastorage media

File/disk directoryFile/disk directory

No indication of No indication of fragmentationfragmentation

• Physical StoragePhysical StorageHow data actually How data actually

resides on your resides on your auxiliary storage auxiliary storage mediamedia

File Allocation Table File Allocation Table (FAT)(FAT)

Fragmentation is normalFragmentation is normal

Measurements of Computer PowerMeasurements of Computer Power• Clock speed: Clock speed: electronic pulses used to synchronize electronic pulses used to synchronize

processing. Faster clock speeds result in more operations processing. Faster clock speeds result in more operations in a give amount of time. Measured in in a give amount of time. Measured in megahertz (MHz).megahertz (MHz).

• Bus width: Bus width: determines how much data can be transferred determines how much data can be transferred at any one time.at any one time. 16 bit, 32 bit, 64 bit. 16 bit, 32 bit, 64 bit.– IBM’s Microchannel (MCA) Architecture vs EISA (open IBM’s Microchannel (MCA) Architecture vs EISA (open

architecture)architecture)

• Word size:Word size: number of bits/bytes manipulated at once. number of bits/bytes manipulated at once. Same as the bus width. Same as the bus width.

• Other determinants include main memory capacity, MIPs.Other determinants include main memory capacity, MIPs.• This is not the same as throughput but it can affect This is not the same as throughput but it can affect

throughput..throughput..