History of Computing - Introduction to Computer Science - Lecture Slides, Slides of Computer Science

Download History of Computing - Introduction to Computer Science - Lecture Slides and more Slides Computer Science in PDF only on Docsity! 1 History of Computing Computer Hardware Docsity.com 4 “Overview Computer Development Computer architecture ® Docsity & 5  City of Philadelphia reportedly experienced brown-outs when ENIAC drew power at its home at the the University of Pennsylvania (http://www.pbs.org/wgbh/aso/databank/entries/dt45en.html)  Was not a general purpose computer: programming meant rewiring with punch cards and switches  One of ENIAC's greatest feats was in showing the potential of what could be accomplished in the future  Transistor - Nobel prize in physics in 1956 Docsity.com 6  Integrated Circuit (chip) - Jack Kilby 1958 (Nobel prize in physics in 2000)  First commercially available IC’s developed by Texas Instruments and Fairchild semiconductor corp.  Generations of IC’s:  Small scale integration - 1965  Up to 100 devices on a chip  Medium scale integration - to 1971  100-3,000 devices on a chip  Large scale integration - 1971-1977  3,000 - 100,000 devices on a chip  Very large scale integration - 1978 to date  100,000 - 100,000,000 devices on a chip  Ultra large scale integration  Over 100,000,000 devices on a chip Apple I computer (1976) Docsity.com 7 Moore’s Law: Number of transistors on a chip will double every 18 months. Docsity.com Computer Components Printer Mouse ——, Keyboard — Ports Modem = Ll CPU RAM Bus ——— Hard disk Disk controller cr Floppy disk drive ma CD-ROM Drive Graphics card Sound card Network card jee$} mM] Monitor $$» Speakers + Cine) Docsity 1am 11 Component description  Central Processing Unit (CPU) or microprocessor, controls the operation of the computer and performs its data processing functions  Main memory - also called internal memory stores instructions and data. Memory is partitioned into separate instruction and data spaces  Input/ output (I/ O) – moves data between the computer and its external environment  System interconnection – some mechanism that provides for communications among the CPU, the main memory, and the I/O devices Docsity.com 12 Structure of the CPU control unit registers flags cache memory ALU input/output storage memory registers Docsity.com 15  Cache Memory: Small fast memory that improves CPU’s efficiency. Increases computer throughput, and is a high-speed holding area for program instructions and data. It holds only instructions and data that are likely to be needed by the CPU. While programs are running on the computer, the same data or instructions might be needed frequently. In such cases, the processor first checks the cache memory for the data or instructions, thereby reducing the need for frequent access to the RAM and speeding up the processing Docsity.com 16 Microprocessor System Buses Microprocessor (CPU) RAM ROM Input/Output (I/O) Control Bus Data Bus Address Bus Docsity.com 17 System Buses  A BUS is an internal communications path consisting of a number of lines connecting the system components  Control bus –The control bus synchronizes system events like memory access, system interrupts, I/O, etc.  Address bus – Source and destination addresses are sent over the address bus to identify a particular location in memory or input/output port.  Data bus – two way path for transferring data and instructions in and out of the microprocessor Docsity.com 20 CPU-Memory Interaction 0 LDA 14 1 ADD 15 2 STA 14 3 HLT …. …… 14 10 15 7 14 17 15 7 Assume a is stored in 14 and b is stored in 15 a= a + b Result Program Fetch-execute cycle Docsity.com 21  ROM – Read Only Memory. ROM can typically be written once, but read many times. It is used to store BIOS (Basic Input/Output System-helps to load and locate an operating system), external to microprocessor, and computer instruction sets, internal to microprocessor  The contents of the ROM are hard wired by the manufacturer in a typical ROM chip. When you turn the computer on, ROM automatically prepares the computer system and loads the initial display screen prompt  A variation of ROM is PROM (Programmable Read Only Memory), in which the user can load programs and data that are read only. This can be done with device called a PROM programmer. Writing to a PROM destroys the internal links, so a basic PROM can only be programmed once Docsity.com 22  EPROMs (Erasable Programmable Read Only Memory) is a variation of PROM, and is rewritable. It can be erased by exposing the chip to ultraviolet light. It can then be programmed with an EPROM programmer  Flash memory is a type of PROM that can be easily altered by the user. They are also called EEPROMs (Electrically Erasable Read Only Memory) because they can be electrically erased then written on to (flashed) without having to take them out of the computer, and without using ultraviolet light.  Since RAM can be read faster than most ROMs, the frequently used content of the ROM is sometimes copied to RAM (shadowed) Docsity.com 25 Input/Output Some Input Devices  Keyboard  Keypad  Mouse  Voice activation  Touch screen  Digitizers and pen-based (stylus) systems Docsity.com 26 Some Output Devices  Monitor  Printer  Speakers  Communication (comm) ports  Modems (both input and output)  Network interface cards (both input and output) Docsity.com 27 Input and Output Devices and Systems Docsity.com IT Fundamentals 30 Types of input Docsity.com IT Fundamentals 31 Input Devices Most obvious = human + KEYBOARD Machines make better input devices…. DIRECT ENTRY, or SOURCE DATA AUTOMATION. Need to be: Accurate, reliable and easy to use, fast Human and keyboard is the most used input device Docsity.com IT Fundamentals 32 Examples of Direct Entry Input Devices MICR : Used with cheques OMR : Tattslotto & TAB OCR : Scan type-written pages…. Scanners Docsity.com IT Fundamentals 35 Other Input Devices a. Sensors Pointing Devices Mouse measures x-y moveent plus whether button is pressed down… Docsity.com IT Fundamentals 36 Other Input Devices TouchPad Pointing Stick Light Pen Trackball - Similar to mouse Joystick - games? - Difficult to pinpoint a position Touch screens screen 'divided' into areas area selected by touch easy to use cannot have areas too small screens get dirty (many uses) Docsity.com Voice Input Step Step 2: User dictates text into microphone. An analog-to-digital converter (ADC) translates sound waves into digital measurements the computer can recognize. Measurements include pitch, volume, silences, and phonemes. Phonemes are sound units such as aw and guh. ADC 19010111010110101100001101 Step 4: <I Step 3. To narrow a list down, the software presents the The software compares the user with a list of choices or uses a natural language spoken measurements to those component to predict the most likely match. in its database to find a match ‘The user may correct any wrong or list of possible matches. selection made by the software. | Matches Natural Language Engine ‘your, youre .- Your write .. You’re right «Your right, write IT Fundamentals 4 37 Docsity.com IT Fundamentals 40 Output Printers Impact printers Dot Matrix: Docsity.com IT Fundamentals 41 Output Non-impact printers - no physical contact between paper and printing device - 3 technologies used: ink jet - thermal - special paper - expensive to run - up to photographic quality… Docsity.com IT Fundamentals 42 Output Laser - need enough memory to hold an entire page - 600 to 2400 dpi and greater - operates similar to a photocopy machine… Docsity.com IT Fundamentals 45 Output LCD Monitors •An electric current passes through the crystals causing them to twist, block light waves and create an image. Gas Plasma Monitors Very high quality (1080p)…. •Larger screens Docsity.com IT Fundamentals 46 Other Output Devices Data Projectors Docsity.com IT Fundamentals 47 Other Output Devices Fax Machine •Transmits and receives documents over the telephone line Docsity.com 50 Secondary Storage Media and Devices Floppy Disks Hard Disks Tape and Tape drive Cartridge tape CD-ROM/DVD/BluRay Magnetic-Optical drive PC Cards Smart Cards USB Drives SECONDARY STORAGE Docsity.com 51 Size Type Tracks Sectors Capacity IBM: 3½ DD 80 9 720KB 3½ HD 80 18 1.44MB Macintosh 3½ HD 1.4MB FLOPPY DISKS: eg. for a 3½ disk (high density): • 3 1/2-inch diskette • Circular piece of plastic • Made up of tracks & sectors • 512 bytes in each sector Docsity.com 52 • Made up of platters, cylinders and sectors • Rotation speed 7200 rpm • head 'floats' on surface • bad sectors & head crash HARD DISKS Docsity.com 55 Other Storage Devices Tape •Thin ribbon of plastic • Sequential storage – mainly for backup •Used for longer term storage USB Flash Drives • plugs into a USB port •Small, lightweight •Storage 4 GB + •Great for mobile users Docsity.com 56 OTHER TYPES OF STORAGE DEVICES PC cards • Small, credit card-sized cards that fit into PC Card expansion slots •Used for storage, communications and additional memory. • Most often used with portable computers • Can store more than 300 MB of data Smart Cards • Credit card-sized devices that contain a microprocessor • Microprocessor can store up to 8,000 bytes of information. • Examples of uses - prepaid telephone card, employee time card Docsity.com