Fundamentals of Computer Processing

1. Fundamentals of Computer Processing

2. Some Basic Terms • Bit – a single unit of information, generally in the form of a 1 or 0, when combined with other bits they can make up words or code in which the computer can understand and process. The name bit comes from the derivation of Binary and unIT, • Byte – a combination of 8 bits, one byte is the length of one character (ex. 10010010) • Binary System –a combination of 1’s and 0’s in order to produce numbers, letters, symbols, and words. These letters and symbols are translated by the computer in the form of ASCII and ECBDIC code. • bps, Kbps, Mbps, Gbps, referred to in terms of the rate of data transfer. Can be known as bauds per second or bits per second, the K, M, G, refer to the metric system of kilo, mega, and gig which translates into 1000, 1,000,000, or 1,000,000,000 bits per second, as one could surmise the larger the number the faster the actual transmission of data that occurs • Megahertz (MHz) a measure of clock speed, or the pacing of a events in a computer; represents 1 million cycles per second; also known as a unit of frequency in this case 1 million hertz • Latency – the number of bits (frames, cells, packets) in transit; a figure that tells us how quickly a given bit a data will move from one point to another within a network, usually equated to delay

3. Some Basic Terminology • Delay – the dominant time interval of the transmission of information, also referred to as the time it takes to send a message from point A to the time it is received at destination point D. Delay is broken down into propagation and transmission delay. • Frequency– number of vibrations per unit time; number of waves that cross a given point per unit time • Wavelength – the spacing of the crests or troughs in a wave train • Analog – a continuous sine wavelength over a certain frequency range with a positive voltage representing a 1 and a negative charge representing a 0; mostly used for voice transmissions • Digital– a discrete flow in which data are coded as 0-bits and 1-bits and transmitted as a series of on-and-off electrical pulses • ITTU/CCITT – (International Telegraph and Telephone Union/International Telegraph and Telephone Consultative Committee) one of the main governing bodies that is responsible for setting the standards of the protocols that we deal with

4. Computer Generations • First Generation 1946-1956 Vacuum Tube • Very large, consumed huge amounts of power and generated much heat, had 2kb RAM, speed of .01 MHz, printing had to be done manually • Second Generation 1956-1963 Transistors • better than vacuum tubes, used less power, less heat, RAM increased to 32kb, speed of .2/.3 MHz • Third Generation 1964-1979 Integrated Circuits • printed transistors on small silicon chips, 2mb RAM, speed of 5MHz • Fourth Generation 1980-Present • VLSIC- very large-scale integrated circuit (the microprocessor), .18 micron, 500 MHz, 256 RAM, commercial machines hold gigabyte storage,1000 MHz

5. Computer Sizes • Mainframes -- the first. Used for business • Supercomputers -- the largest, very complex • Minicomputers -- the first effort to achieve reduced size (middle-ranged) • Microcomputers -- made possible by microprocessor PC -- used by one person, or by a few people in the same area Workstations, lap tops, notebooks, and palmtops

6. The Computer Schematic

7. The Computer Bytes • Computers deal in either • ASCII- American Standard Code for Information Interchange (7 bits with 1 parity bit) • EX. A = 01000001 • EBCDIC- Extended Binary Coded Decimal Interchange Code an 8-bit code used in IBM • EX. A = 11000001

8. Understanding Bits and Bytes

9. Converting to Binary

10. The Computer Process Cycle • ALU- Arithmetic-Logic Unit • performs the principal logical and arithmetic operations • determines quantities, logic operations such as binary codes pertaining to letters or numbers • Control Unit • coordinates and controls other parts of the computer system. The series of operations required to process a single instruction is called a machine cycle.

11. The Machine Cycle • Instruction Cycle • the control unit retrieves one program from primary storage and decodes it. It places part of the instruction in the ALU. • Execution Cycle • the control unit locates the required data in primary storage, places it in a storage register, instructs the ALU to perform the function, finally places the result in primary storage • As each instruction is completed the CU advances

12. CPU Clock Speed Example Parameters 1,000,000 cycles per second 100 cycles to handle the communications interrupt 8000 characters/second = 64,000 bits/second Formula X characters/second * X cycles/characters = % Communication use of CPU Total cycles/second 8000 chars/sec * 100 cycles/characters = 80% 1,000,000 cycles/sec

13. The Computer Schematic Central Processing Unit (CPU) Control Unit Primary Storage Unit Output Information InputData Arithmetic and Logic Unit Secondary Storage Unit

14. Improving Performance • There are three main ways to accomplish this • word length -the number of bits that can be processed together as a unit • current computers are either 16 or 32 bit • bus width - the amount of bits that can be transferred within the computer at any given computer interrupt • bus width range also varies • clock speed • RISC- reduced instruction set computing • MMX- MultiMedia eXtension

15. Computer History • Prior to 1950s • Keydriven machines • (some were called bookkeeping machines) • Punched card machines

16. Computer History Cont. • 1951 -- first commercial computer (a UNIVAC I) installed at the Census Bureau • 1954 -- first computer installed in a business (another UNIVAC I at GE) • Early 1970s -- minicomputers • Late 1970s -- microcomputers (TRS-80, Commodore PET) • 1982 -- IBM PC

17. Other Computer Parts • Secondary Storage • long-term nonvolatile storage of data outside of CPU and primary storage • retains data even when power is turned off • requires mechanical movement to gain access to data, much slower than primary storage (which moves at the speed of light) • types of secondary storage • magnetic tape • hard disks • CD-ROM, CD-R, CD_RW • WORM (write once, read many) • DVD • RAID -Redundant Array of Inexpensive Disks • Direct Access Storage Device

18. Secondary Storage to Processing • Batch processing - hold transactions in a group and once a ‘batch’ has been accumulated, process all the transactions • many batches are on a daily, weekly, or monthly cycle • Online processing - as a transaction is received, process the transaction without waiting for a batch of them to accumulate • Realtime systems - often used to control a physical system

19. Batch Processing Batch transaction data Sort into item number sequence Step 1 Sorted transaction data Old Inventory file Step 2 Update inventory file New Inventory file Transaction data Step 3 Sort into customer number sequence

20. Batch Processing (continued) Sorted transaction data Old Accounts Receivable file Update Accounts Receivable file Step 4 New Accounts Receivable file Transaction data Step 5 Sort into salesperson number sequence Sorted transaction data Old Sales Analysis file Update Sales Analysis file Step 6 New Sales Analysis file

21. Inventory Online Processing Enter single transaction record Files Accounts Receivable Update Sales Analysis

22. Direct Applications Determine Media Applications Batch Online Realtime Sequen- tial

23. Input Devices • Keyboard • Ergonomic considerations (human engineering, human factor considerations) • QWERTY keyboard vs. Dvorak keyboard

24. Input- Pointing Devices • Mouse • Trackball • Touch screen • Light pen • Remote control device

25. Source Data Automation (SDA) • Input bottleneck • Optical character recognition (OCR) is big in retailing • Supermarket scanners (bar code) • Point of sale (POS) terminals • Handprint, character readers • Magnetic ink character recognition (MICR) was big for banks starting in the late 1950s • digital scanners • pen/voice input - the UPS example, voice recognition programs • sensors

26. Speech Recognition • Speaker dependent • Speaker independent

27. Output Devices • Displayed • CRT- Cathode Ray Tube - most popular, allows for bit mapping (this is how you can manipulate photo images) • Flat-panel • Printed • Speed • Quality • Speech (audio response unit) • digitized or playback

28. Means of Producing Computer Output Displayed Output Devices Printers ABC123 Computer Speech Output Devices Plotters Microfilm

29. Output Devices Cont. • Plotters • Flatbed • Drum • Microform • Microfilm (roll) • Microfiche (sheet) • Tabular versus graphical versus narrative

30. Printers Impact Nonimpact Line Character Page Ink jet Laser Dot matrix Daisy wheel

31. Types of Processing • Serial Processing/ Central Processing - • one computer one result • Parallel Processing/ Distributed Processing • many computers to achieve one result • Client/Server Computing • a model that allows ‘clients’ to connect to a main server to allow quicker processing and sharing • Downsizing- The process of transferring applications to smaller ones.

32. Network Computing • The idea of thin clients • the bulk of processing occurs on the server • Is this cheaper? The idea of TCO • total cost of ownership • What about failures?, No access to data.

33. Future of Computers • Multimedia Capabilities • Real Vid, Tivo • MP3 • Smart Cards • Massively Parallel Computers, MERCED

34. What does this mean to IT? • Increasing technology • What do we purchase? Why? • How will it impact performance? • How will it affect our current IT investment?