Computer Systems 1 Fundamentals of Computing The Computer System: Core Concepts

Computer Systems: The Core Concept Input, Process, Output Devices RAM Backing store Computer architecture Core 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 RAM INPUT OUTPUT PROCESS 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 Processing Output 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 RAM BIOS 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 01100010 11010001 11100001 RECEIVER Computer Systems 1 (2004 - 2005)

Serial & Parallel Data Transmission Parallel Transmission SENDER RECEIVER 1 1 1 1 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) Disk Platter Read/Write Heads Spindle Magnetic storage medium Uses rotating metal disks (platters) Use read and write ‘heads’ to store and retrieve information Large storage capacity Disk Platter Spindle Read/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: Cluster Sector Track Computer Systems 1 (2004 - 2005)

Types of Computer Personal Computer (PC) Supercomputer Mainframe 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 Computer Systems 1 (2004 - 2005)