Computer Systems 1Fundamentals of Computing

The Computer System: Core Concepts

Computer Systems 1 (2004 - 2005)

Computer Systems: The Core Concept Input, Process, OutputDevicesRAMBacking storeComputer architectureCore Hardware

Computer Systems 1 (2004 - 2005)

Input Sending information to the computer Issuing the computer with a command Devices for Input

Keyboard Mouse Scanner Camera Joystick / Gamepad Microphone (Transducer) Lightpen Barcode Reader Fingerprint Scanner

Computer Systems 1 (2004 - 2005)

Output Returning the result of a process Querying the user Providing the user with feedback Devices for Output

Monitor Printer Plotter Digital Projector Speakers Synthesiser Robot / Machine LED’s

Computer Systems 1 (2004 - 2005)

More Hardware Employing RAM and backing store

INPUT OUTPUTPROCESS

RAM

Backing Store

Computer Systems 1 (2004 - 2005)

Random Access Memory (RAM)

Used to store instructions that are in current use Two main types of RAM:

Static RAM (SRAM) reliable does not need to be constantly refreshed fast expensive

Dynamic RAM (DRAM) more common slower than SRAM cheap must be constantly refreshed

Both volatile (contents lost when power is off)

Computer Systems 1 (2004 - 2005)

Random Access Memory (RAM)

Cache Memory Essentially RAM that the CPU can access quickly

Is physically close to the processor

Usually always SRAM Therefore, small sizes are common compared to size of RAM

Two levels of cache memory Level 1 - Situated inside the processor

Commonly 512 kb Level 2 - A separate RAM chip on the motherboard or in

expansion slot Commonly 1024 kb (1 Mb)

Computer Systems 1 (2004 - 2005)

Storage Place to keep important data Kept on a storage medium

Magnetic, Optical, physical Devices for Storage

Hard Disk Drive (HDD) Floppy Disk Drive (FDD) Zip Drive Tape Drive CD / DVD (ROM, RW, R) Memory Chips (USB sticks, Flash memory) Punched Cards Barcodes

Computer Systems 1 (2004 - 2005)

More Hardware Employing RAM and backing store

RAM = Random Access Memory Sometimes called ‘main memory’ Used for temporary storage

Contents are erased when power is off Very fast access to data

Any byte can be accessed randomly

Backing store Permanent place to keep important data Commonly a hard disk drive

Allows reading and writing of data Could also be a ROM (Read Only Memory) chip

Once written to can only be read in future

Computer Systems 1 (2004 - 2005)

More Hardware Peripheral Hardware Components

Input Scanner, microphone, light pen

Processing Graphics card, sound card

Output Speakers, plotter, digital projector

Memory Extra RAM, VRAM

Permanent storage Zip drives, memory sticks, floppy disks

Other Devices Modem, NIC, DVD-R, DV-Camera

Computer Systems 1 (2004 - 2005)

Computer Architecture What’s in the box?

CPU

Hard Disk Drive

RAMBIOS

Sound Card

Graphic Card

Ports

Floppy Disk Drive

Power Supply

Computer Systems 1 (2004 - 2005)

CPU Central Processing Unit Carries out all calculations

Logic functions

Controls hardware and devices in the system Speed measure in Megahertz (MHz)

Oscillations per second 1 Hz = 1 oscillation every second The higher the MHz value, the faster the processor

On paper (theoretically)

Computer Systems 1 (2004 - 2005)

BIOS Basic Input Output System (BIOS) Provides the computer with basic functionality Built-in software, no disk access

Usually a ROM chip on the motherboard

Common BIOS manufacturers Award, Compaq, HP

Stored on a ROM chip Settings are saved to a CMOS chip, powered by a

battery CMOS = Complementary Metal Oxide Semiconductor

Computer Systems 1 (2004 - 2005)

Ports Physical interface or socket to connect a device to a

computer Interfaced to the computer’s motherboard Two main types of port:

Serial Data is transferred in streams One bit after the other

Parallel Data bits are transferred alongside each other in waves

(concurrently) Common ports

USB (Universal Serial Bus) Serial (9-pin) & (15-pin ‘game’ port) Parallel (25-pin) SCSI (Small Computer Systems Interface)

Computer Systems 1 (2004 - 2005)

Serial & Parallel Data Transmission

Serial Transmission

SENDER RECEIVER01100010 11010001 11100001

Computer Systems 1 (2004 - 2005)

Serial & Parallel Data Transmission

Parallel Transmission

SENDER RECEIVER

110

1

10

00

Computer Systems 1 (2004 - 2005)

Sound & Graphic Cards Interface directly onto the motherboard Graphics Card usually uses the AGP

(Accelerated Graphics Port) Provides basic and / or advanced graphics capability Often have graphics co-processors On-board VRAM (Video RAM)

Sound card uses a PCI (Peripheral Component Interconnect) slot Allows computer to output sound to speakers and record

sounds. Adds MIDI (Musical Instrument Digital Interface) capability

Computer Systems 1 (2004 - 2005)

Hard Disk Drives (HDD) Magnetic storage medium Uses rotating metal disks (platters) Use read and write ‘heads’ to store and retrieve

information Large storage capacity

Disk Platter

SpindleRead/Write Heads

Computer Systems 1 (2004 - 2005)

Floppy Disk Drive (FDD)

Magnetic storage medium Uses rotating single, thin magnetic disk Requires a drive to read the disk, which has the

read/write heads Small storage capacity

Typically 1.44 Mb (High Density 3.5”) Portable Cheap

Computer Systems 1 (2004 - 2005)

Magnetic Disks How the disk works:

Sector

Cluster

Track

Computer Systems 1 (2004 - 2005)

Types of Computer Personal Computer (PC)

Single-user computer Standalone

Supercomputer Very fast computer which can carries out huge

amounts of instructions per second

Mainframe A powerful computer which can be used by lots of

users at the same time

Computer Systems 1 (2004 - 2005)

COMPUTER EXPLAINED

Computer Systems 1 (2004 - 2005)

CS1: Week 2 What you know now:

More about Input, Process, Output Features and functions

How RAM and backing store integrate into the computer system

Computer architecture Ports Sound and graphics

Backing store Methods Magnetic storage