Unit B – Software, Files, and Computer Architecture

1. Unit B – Software, Files, and Computer Architecture Pages B1 – B26 of the Concepts Book

2. Software • Program – a set of instructions that tell the computer what to do and how to do it • What language is shown on page B-3? • Data vs. Information • Data is basic or raw, unprocessed input (numbers) • Information is processed or assembled data (chart) • Software (by the book’s definition) includes programs (instructions) and associated data • System Software (machine) vs. Application (user)

3. Operating Systems • Software that controls the computer • Acts as go-between for applications and hardware • External vs. internal services • Performs basic input and output • Allocates and manages all system resources • Allows for multitasking • Multitasking means the computer can perform more than one complex operation at one time • What’s the difference between multitasking and multiuser? • Detects (causes?) hardware failures • Maintains security

4. Device Drivers • Addition to the operating system • Incorporates instructions needed for the computer to communicate with a specific (type of) device not previously present • Usually must be installed before and/or after the device (Plug and Pray?) • May be prompted to install • Software may be on disk or CD, or online

5. Windows • What company had the rights to the first windowing system, and what happened? • Which competitors continued the concept? • Microsoft Windows 1.0, 2.0, 3.0 • Microsoft Windows 3.11 (networking) • Microsoft Windows 95, 98, NT, 2000, ME • Office versions vs. Windows versions

6. Applications • Applications perform a specific task or a related set of tasks • Productivity word processing, spreadsheet, database • Suite combination of compatible applications • Groupware collaboration and revision • Business software • Horizontal – wide range of customers (payroll) • Vertical – specific type of customer, different levels • Other classifications on B-9

7. Logical File Storage • Conceptual way data is stored • Two common representations • Filing cabinet or cardboard boxes • Tree • Each file has a name +/- an extension • Extension can tell you the data/file type • Extension used to determine which program opens file – “document centricity”

8. Data Files vs. Executables • Data files contain words, numbers, pictures, reports, graphs (information?) • DAT, DOC, XLS and TXT • Executable files contain instructions that the computer executes to perform a task • EXE, BAT, and COM • Some executable files can be started by users (EXE and COM files); other executable files (DLL, OCX, and VBX files) are started by other executable programs.

9. File Name and Directory Points • A directory is a discrete portion of a storage device (folder or branch) • Root directory is the main list of all files and subdirectories on a volume • Each storage device has a device letter (?) • The file name is a unique combination of a name +/- an extension • A complete or qualified filename includes the full path (list of directories and drive letter) • Cannot have two files on same device with same complete file name!!!

10. File Name Anomalies • Operating system considerations • Web considerations • Forward and backward slashes • Certain characters cannot or should not be used in file names • Wildcards 

11. Physical File Storage • Storage medium is the substance that contains the data • Storage device records and retrieves data from the medium • Saving a file is also called storing or writing a file; retrieving a file is also called opening or reading a file

12. Once Bitten . . . • Data is stored digitally in bits (1s and 0s) • Kilo = 210 = 1,024 ~1,000 • Mega = 220 = 1,048,576 ~1 million • Giga = 230 = 1,073,741,824 ~ 1 billion • Tera = 240 = 1,099,511,627,776 1000 gigabytes • 1 byte = 1 character = 8 digits • What’s a nybble?

13. Types of Storage Devices • Hard Disk • 20 megabytes to 120 gigabytes • Used for long-term storage, applications, large files • Floppy Disk – Figure B-14 • 5 ¼” floppy • 3 ½” floppy (SD, DD, HD) • Zip Disk (is this really a “floppy”?) • Used for distributing, storing, and backing up relatively small files

14.  Storage Device Speed Factors • Access time is the average time required to locate and read a given piece of data • Access time is measure in ms (milliseconds) • Random vs. sequential access devices • Data transfer rate (sort of) indicates the quantity of data that can be moved in one second

15. Magnetic Storage • Blank media start with randomly-scattered patterns on magnetic-oxide-covered Mylar • Read-write head polarizes particles into a pattern which holds data • Pattern can be “erased” or “reformatted” • Double-sided vs. double-density • Tracks, Sectors and Clusters, oh my! • Death Knells for Storage

16. Optical Storage • Microscopic dark and light spots (“pits” and “lands”) burned onto the medium • Is optical storage changeable? • CD vs. CDR vs. CDRW • Crystalline innovations • Molecular innovations

17. Computer Architecture • Integrated Circuit – basic component • Crystal or wafer with embedded wires, transistors, and resistors • Encased in ceramic or plastic carrier, usually with pins • DIP, SIMM, DIMM, PGA (pin grid array, Pentium) • Motherboard, daughterboards/cards, ports • Power supply • Storage (hard and floppy disks) • Wires, cables, battery, fan, bus, etc.

18. Memory • Memory vs. storage • Memory can be classified as long- or short-term, as can storage • Text says that memory circuits have a direct link to the processor, while storage media do not • CMOS = Complementary Metal-Oxide Semiconductor • ROM = Read-Only Memory • Remains after power is off • RAM = Random Access Memory • Erased when power is removed • Memory speed • Nanosecond = one billionth of a second • 60 to 80 was norm, now < 8 ns • SDRAM is a fast type of memory • What is virtual memory?

19. The CPU(Central Processing Unit) • Performs arithmetic and logic functions and executes instructions • RAM sends data and instructions to the CPU, which returns processed data to RAM • For a microcomputer (PC), the CPU is called a microprocessor • Intel, Cyrix, AMD – are they compatible? • Pentium heats up the market • Anyone want some Celeron soup?

20. Stuff You Just Might Possibly Have a Chance of Encountering on a Test Someday • Issue: Is Data Getting Lost? • Independent Challenges 3, 4, and 8 • Visual Workshop