Stuart Cunningham - Computer Platforms COMPUTER PLATFORMS Input, Output, and Storage & Introduction to Basic Computer Architecture Week 2

Stuart Cunningham - Computer Platforms Week 2 Input, Output, Storage –Devices –Media Computer Architecture –The CPU ALU Control unit Registers –Buses –Von-Neumann

Stuart Cunningham - Computer Platforms 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

Stuart Cunningham - Computer Platforms 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

Stuart Cunningham - Computer Platforms 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

Stuart Cunningham - Computer Platforms Computer Architecture What’s in the box? CPU Hard Disk Drive RAM BIOS Sound Card Graphic Card Ports Floppy Disk Drive Power Supply

Stuart Cunningham - Computer Platforms 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)

Stuart Cunningham - Computer Platforms 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

Stuart Cunningham - Computer Platforms 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 Spindle Read/Write Heads

Stuart Cunningham - Computer Platforms 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

Stuart Cunningham - Computer Platforms Magnetic Disks –How the disk works: Sector Cluster Track

Stuart Cunningham - Computer Platforms 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 Settings are saved to a CMOS chip, powered by a battery –CMOS = Complementary Metal Oxide Semiconductor

Stuart Cunningham - Computer Platforms 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)

Stuart Cunningham - Computer Platforms 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)

Stuart Cunningham - Computer Platforms

Central Processing Unit (CPU) CPU has three important parts: –ALU (Arithmetic and Logic Unit) –Control Unit –Registers High Speed Registers ALU Control Unit CPU

Stuart Cunningham - Computer Platforms Central Processing Unit (CPU) Arithmetic & Logic Unit –Handles mathematical and logical functions (numerical) –Deals with non-numerical logic operations Control Unit –Handles all low-level hardware operations Input & Output Devices and CPU –Carries out instruction handling Fetch Execute Cycle Registers –Storage areas within the CPU –Accessible at high speed –Anything for processing must be kept in a register –Can also hold the address of a memory location

Stuart Cunningham - Computer Platforms Buses A collection of wires which connects together the internal components of the computer –Allows transfer of data Main types of bus: –Data bus Carries actual data bits (information) –Address bus Transfers locations where data should be sent –Control bus Carries status information

Stuart Cunningham - Computer Platforms Buses How buses fit into the computer system INPUTOUTPUT CPU MEMORY ADDRESS BUS DATA BUS CONTROL BUS

Stuart Cunningham - Computer Platforms Computer Architecture The Von Neumann Model – –Mathematician –Quantum physicist –Worked on ENIAC Electronic Numerical Integrator and Computer Major development in computer technology –Responsible for developing the Fetch Execute Cycle, and his namesake - ‘Von Neumann Model’ –The original computer geek?!

Stuart Cunningham - Computer Platforms Week 2 What we know now! –Input, Output, Storage Devices Media –HDD –FDD –How magnetic Disks work –Computer Architecture BIOS Ports The CPU –ALU –Control unit –Registers Buses Von-Neumann