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Introduction to Computer Science (I)

Inside the Computer

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Computer System

• A computer system consists of– Hardware: The set of electronic elements

required to run programs– Software: The set of instructions to be run on

the hardware– Data: Raw facts as input to the computer. After

processed, useful information as the output of the computer is produced

– User

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Binary Digits: 1 and 0

• Types of signals– Analog: Continuous waveforms in which

variations in frequency and amplitude can be used to represent information

– Digital: Discrete signals in two states. Generally, the on state is expressed or represented by the number 1 and the off state by the number 0

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• Digitalized data in computers– Letters– Numbers– Colors– Sounds– Images– Odors

• Bit: An on or off electronic state– On-bit: 1– Off-bit: 0

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• On and off states inside the computers– RAM: Presence or absence of an electrical

charge in an integrated circuit

Source: http://www.intel.com/research/silicon/nanotechnology.htm

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– Disk storage: Two states are represented by the magnetic arrangement of the surface coating on magnetic disks

Source: http://www.research.ibm.com/resources/news/20010518_whitepaper.shtml

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– CD and DVD: Digital data are stored permanently as microscopic pits

Source: http://www.opticaldisc-systems.com/2002SepOct/DVDBASICS80.htm

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– Fiber optic cable: Binary data are pulses of light

– Electrical transmission media: Binary numbers are electrical signals

Source: http://www.bsu.edu/web/CBTHORNBERRY/trends5.html

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• Character encoding systems: bits and bytes– Byte: The 8-bit combination of bits are used to

represent a character– ASCII: The 7-bit ASCII (American Standard

Code for Information Interchange) code can represent up to 128 characters

Source: http://www.unicode.org/charts/PDF/U0000.pdf

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– Unicode: A 16-bit encoding system to represent more characters than the English language

Source: http://www.unicode.org/charts/PDF/U4E00.pdf

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The Components of A Computer

• Von Neumann architecture– The model of computing proposed by John Von

Neumann (1903-1957) in 1946– The stored program computer

• The instructions that control the operation of the computer be encoded as binary values and stored internally in the memory unit along with the data

– The basis of the structure and organization of virtually all modern computers

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– Include four major subsystems called memory, input/output, the arithmetic/logic unit (ALU), and the control unit

Memory MemoryControl unit

ALU

Processor

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– The first stored program• Maurice Wilkes of the University of Cambridge

created the first stored program on a machine, called EDSAC, which calculated and printed the table of squares on May 6, 1949.

Image courtesy of Computer History Museum, http://www.computerhistory.org

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• The major devices of a personal computer– The PC system unit– Storage devices– Input devices– Output devices

StorageDevices

CPUOutputDevicesControl Unit

InputDevices ALU

Main Memory

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The PC System Unit

• The motherboard– A single circuit board provides the path through

which the processor communicates with memory components and peripheral devices

– Attached devices• Processor

• Support electronic circuitry, such as the chipset

• Memory chips

• Expansion boards

T. K. Yin, NUK-CSIE Source: http://www.asus.com

1

2

34

5

6

7

1: Processor socket

2: DIMM sockets

3. Floppy connector

4: Hard disk connectors

5: Chipset

6: PCI expansion slots

7: AGP video cord slot

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1: PS/2 mouse port

2: Parallel port

3: RJ-45 port

4: Line In port

5: Line Out port

6: Microphone port

7: USB 2.0 ports 1 and 2

8: VGA por

9: S/PDIF out port (digital audio)

10: USB 2.0 ports 3 and 4

11: PS/2 keyboard portSource: http://www.asus.com

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• The processor– Called the central processing unit or CPU– The nucleus of any computer system– Contains the control unit and the arithmetic and

logic unit– Companies

• Intel: Pentium 4, Celeron, Xeon, Itanium

• Motorola: 680x0

• AMD: K6, Duron, Athlon

• Apple/Motorola/IBM: Power PC

• Sun: SPARC

• Compaq: Alpha

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• DRAM (dynamic random access memory)– A high-speed holding area for data and program

s– Types

• SDRAM (synchronous DRAM)• VCM (virtual channel memory)• DRDRAM (direct rambus DRAM)• DDR SDRAM (double data rate SDRAM)

– Module• SIMM (single in-line memory module)• DIMM (double in-line memory module)

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VCM

DRDRAM

DDR SDRAM

200 PIN DDR333 256MB SO-DIMM

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• Cache memory– Level 1 cache: Built into the processor– Level 2 cache: On another chip, sitting between the processor and RAM

• Volatile memory– DRAM– SRAM (static RAM): Used in cache memory

• Nonvolatile memory– ROM (read only memory)

• When you turn on a microcomputer system, aprogram in ROM automatically readies the computer for use and produces the initial display-screen prompt

– PROM (programmable ROM)– Flash memory

• The PC’s BIOS (basic input output system) is stored in flash memory

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• CMOS (complementary metal-oxide semiconductor ) – A type of memory chip with very low power

requirements, and in PCs it operates using small batteries. In PCs, CMOS is more specifically referred to as CMOS RAM.

– Store information your computer needs when it boots up, such as hard disk types, keyboard and display type, chip set, and even the time and date.

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• Buses and ports– The motherboard and its system bus must be linked to

input, output, storage, and communication devices to receive data and return the results of processing

– PCI local bus• The PCI local bus (peripheral component interconnect) enables

circuit boards with extra features to be linked to the common system bus

– AGP bus• The AGP bus (accelerated graphics port) is a special-function

bus designed to accommodate the throughput demands of high-resolution 3-D graphics

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– USB• The USB (universal serial bus) is the primary standard for connecting peripheral

devices to a PC• The USB hub is a device connecting to a USB port and offering three, four, or fiv

e additional USB ports• USB 2.0 permits data transfer at 480 Mbps, about 40 times faster than the original

USB standard

– 1394 or FireWire bus• The 1394 bus supports data transfer rates of 400 Mbps for the original standard an

d 800 Mbps for the current standard

– SCSI bus• The SCSI bus (small computer system interface) was an early alternative to using

expansion slots to extend PC functionality• Up to 15 SCSI peripheral devices can be daisy-chained to a SCSI interface expan

sion card via the SCSI port

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– Serial port• The 9-pin or 25-pin RS-232C connector

• An external modem might be connected to a serial port

– Parallel port• Parallel ports use the same 25-pin RS-232C connect

or

• Printers used parallel ports

– IrDA port• The infrared port transmits data via infrared light wa

ves

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USB connectorPS/2 keyboard connector

1394/FireWire connector Ethernet connector

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SCSI cable

Printer connector

Video/monitor cable

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• Expansion boards– Graphic adapter

• Normally an AGP board

– Sound• Typically has receptacles for a microphone, a

headset, an audio output and most has a port for a game controller and a MIDI (music instrument digital interface) port

– Data/voice/fax modem– Network interface card– SCSI interface card– Video capture card

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Sound card Graphics adapter

SCSI interface cardNetwork interface card

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• PC cards– The PCMCIA card is a credit card-sized

removable expansion module that is plugged into an external PCMCIA expansion slot on a PC, usually a notebook

– Extended RAM, programmable nonvolatile flash memory, network interface cards (wireless and wired), data/voice/fax modems, hard-disk cards

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PCI card and PCMCIA radio card PCMCIA hard disk

PCMCIA flash memory

PCMCIA wireless network interface card

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• Processor description– Word size: bits handled as a unit

• 32 bits

• 64 bits

– Core speed• PCs

– MHz (millions of clock cycles per second)

– GHz (billions of clock cycles per second)

• PCs, workstations, server computers– MIPS (millions of instructions per second)

• Supercomputers– FLOPS (floating point operations per second)

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– Bus speed• MHz

• GHz

• Memory capacity– Kilobytes (KB): 1024 ( ) bytes– Megabytes (MB): 1,048,576 ( ) bytes– Gigabytes (GB): bytes– Terabytes (TB): bytes

202

102

302402

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Storage Devices

• Magnetic disk storage– Fixed disks

• Hard disks

– Interchangeable disks• Floppy disks: 1.44 MB

• SuperDisk: 120 MB

• Zip disks: 100, 250, 750 MB

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Floppy disk Hard disk

Zip diskSuperdisk

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• Optical laser discs– CD formats (650MB)

• CD audio (compact disc): 4.72 inch

• CD-ROM (compact disc-read-only memory)– 32X, 40X, 75X: Spin at 32, 40, and 75 times the speed of t

he original CD standard

– Original 1X CD-ROM data transfer rate: 150 KB per second

– Spin more quickly when accessing the data near the center (about 450 rpm) and more slowly for data near the edge (about 250 rpm)

• CD-R (compact disc recordable)

• CD-RW (CD-ReWritable)

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– DVD formats (4.7 GB or 9.4 GB for double sided)

• DVD (digital video disc) audio, DVD video

• DVD-ROM– The data transfer rate is nine times that of a CD-ROM spin

ning at the same rae

• DVD+R, DVD-R: Like CD-R

• DVD+RW, DVD-RW: Like CD-RW– DVD-RW (DVD-R) and DVD_RW (DVD+R) are compet

ing technologies

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CD-R disc DVD-RW disc

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• Solid state storage– Flash memory

• Mini USB drive

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Input Devices

• Keyboard• Mouse• Point-and-draw devices

– Trackpad: Common on notebook PCs– Trackpoint: Usually positioned in or near a notebook’s

keyboard– Trackball: A ball inset in a notebook PC or as a separat

e unit– Joystick– Digitizer tablet and pen

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Keyboard Mouse

Trackpad Trackpoint

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Trackball Joystick

Digitizer tablet and pen

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• Scanner– Handheld label scanner

• Read data on price tags, shipping labels, inventory part numbers, book ISBNs

• Sometimes called wand scanners

– Stationary label scanner• Applications like wand scanners

• Common in grocery stored and discount stores

– Document scanner• Scans documents of varying sizes

• Read envelopes at the U.S. Postal Service, and also read turnaround documents for utility companies

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Handheld label scanner

Stationary label scanner

Document scanner

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• Image scanner– Page image scanner

• The scanned result is a high-resolution digitized image

– Hand image scanner• Rolled manually over the image to be scanned

• Badge reader (for magnetic stripes and smart cards)– The magnetic stripes on the back of charge cards and

badges offer another means of data entry

• Speech recognition– Consists of software, a generic vocabulary database, and

a high-quality microphone with noise-canceling capabilities

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Hand image scanner Page image scanner

Badge reader

Speech recognition

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• Digital camera

• Desktop digital video camera– Webcam

• Digital video cameras that are continuously linked to the Internet

– Real-time Internet-based videophone conversations

• Digital camcorder

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Digital cameraWebcam

Digital camcorder

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Output Devices

• Monitors– CRT– Flat-panel

• LCD (liquid crystal display): Active matrix or passive matrix

• TFT (thin film transistor) LCD: Active matrix

– Touch screen• Has pressure-sensitive overlays that can detect

pressure and the exact location of that pressure

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– Monitor resolution• The number of pixels that can be displayed

– 1024*768

• The number of bits used to represent each pixel– 8-bit color mode: 256 colors

– 16-bit high-color mode: 65,536 colors

– True color, either 24-bit or 32-bit mode

• The dot pitch of the monitor– Dot pitch: The distance between the centers of adjacent

pixels

– .28 mm, .25 mm

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CRT monitor TFT LCD monitor

Touch screen monitor

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• LCD projector• Printer

– Laser• Nonimpact• 600 dpi (dots per inch), 1200 dpi

– Ink-jet • Nonimpact• The droplets, ehich dry instantly as dots, form the le

tters and images

– Large-format ink-jet, or plotter– All-in-one multifunction device: Print, fax, scan,

and copy

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LCD projector Ink-jet printer Laser printer

Large-format ink-jet printer Multifunction device

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• Sound System– Small speaker– 6.1 sound system

• Voice-response system– Recorded voice– Speech synthesis

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References

• Computers– Larry Long & Nancy Long, Twelfth Edition, Pearson Education, Inc

• Invitation to Computer Science, C++ Version– G. Michael Schneider & Judith L. Gersting, Third Edition, Course Tech

nology

• Computer History Museum– http://www.computerhistory.org

• http://archive.computerhistory.org/