Day 1 Material for the 7-day Computer Course

(Prepared in January 2003 by Rituraj Kalita as per the syllabus. Copyright reserved.)

Basics of Computers and Computer-Operation

Computer is a modern tool for storage, processing (i.e., analysis & transformation etc.) and retrieval of information in a very convenient way, and have the flexibility to be programmed to do that in a wide variety of ways. Though it was originally meant for lengthy and cumbersome computations (hence the name), nowadays it's also used for tasks such as word-processing & desk-top publishing, database management, worksheet processing, image (picture) processing, processing of audio and audio-visual data, instrumental investigations of medicinal, chemical and geological nature and so on. The first working computer (called ENIAC) was built as late as in 1947, and was the size of several rooms! The boom in personal computers entering the households is a much recent phenomenon of the late twentieth century, and so is the interconnections (called the Internet) of the world's computers. Here we'll practically restrict ourselves to personal computers (PCs), which are of either desktop (the common form) or laptop variety.

As computers are programmable, so its constituents include the physical (concrete) components called the hardware as well as the untouchable (abstract) components of instructions (programs etc.) therein called the software. The hardware includes internal components inside the computer-cabinet box such as CPU (central processing unit), hard disk(s) for storage, removable disk drives that accept floppy diskettes & CDs (compact disks), the power-box called SMPS, internal speaker, internal modem etc. as well as the external ones outside the cabinet box such as Monitor (VDU), Keyboard, Mouse, External Speaker, Printer, External Modem, Microphone, Scanner, Digital Camera, interconnecting cables etc. Out of these, monitor, speaker, printer etc. are output devices whereas keyboard, mouse, microphone, scanner etc. are input devices for the obvious reasons. The computer-set are packaged and sold as a whole by well-known companies such as IBM, HP, Acer, Toshiba, Compaq, Wipro, HCL, PCS, Zenith etc.; such sets are called branded computers. Some small firms and even individuals buy hardware components by the component-producer companies such as Intel, Cyrix, Seagate, HP, Samsung, Epson, Logitech, D-Link, Microtek, Frontech etc., and assemble them into computer sets without a brand-name for the sets, which are called assembled computers.

The CPU is a name for the conglomeration of three physical components: the Motherboard, the Processor and the RAM (Random Access Memory). Theoretically, it is considered as a combination of the CU (Control Unit), ALU (Arithmetic & Logic Unit) and the Memory. This memory or RAM we're talking about is the Electronic memory that can retain information only when the power is on, as distinguished from Magnetic memory in hard disks, floppies or CDs that can retain even without power supply. The speed of the processor clock (400 MHz, 866 MHz, 1.5 GHz etc., Hz is cycle per second, M & G means practically million & billion) along with its quality (Pentium II, Pentium IV etc. in case of Intel) and the amount of electronic memory (64 MB, 128 MB etc., B meaning byte is the unit of information practically equaling an alphabet or digit) in conjunction with the quality of the motherboard (810 chipset, 815 chipset etc.) determines the speed of most internal computer operations. However, speed of operations involving retrieval of data from hard disk or CDs depend on their quality as well. Quality of hard disk drive is understood from its storage capacity (20 GB or 40 GB etc., roughly equivalent to four or eight million printed text pages!), type (ATA, Ultra-ATA etc.) and brand (Seagate etc.). The CD drive is the device that can hold a CD and read or write data into it. It is of two types: (i) cheaper CD-Reading drives (speed expressed as 48x, 50x etc.) that can only read data from CD (ii) Costlier CD-Writer drives (speeds expressed as 4x, 8x etc.) that can write data into CDs as well. They are made by Samsung, Frontech etc. The CDs (a CD can hold more than 600 MB of data!) also comes in two forms: (i) cheaper CD-R into which data can be written only once (made by Samsung etc.) (ii) costlier CD-rewritable which can be rewritten (made by HP etc.). The rewriting facility looks enticing, but a CD-R can never be infected by a virus after it was first filled with data. The DVDs look exactly similar to CDs, but can hold several GB of data per disk, and can only be read by a DVD-drive (a DVD-drive can read CDs also). A floppy drive (made by Sony etc.) can hold a floppy diskette, and read & write data into it. It now universally comes in the 1.44 MB, 3.5 inch variety, the older varieties getting practically extinct. As is obvious to you, a floppy diskette (made by Sony, Phillips etc.) can hold up to 1.44 MB (around 1440 KB, K means practically thousand) of data, considered a rather small amount nowadays. The power box called SMPS is a comparatively cheaper component of the computer. The internal speaker is a rather crude speaker to emit some operational sounds, particularly for indication of errors, and so to play musical or verbal sounds a set of external speakers is a must.

Coming to the components external to the cabinet box, the monitor i.e., the VDU (Video Display Unit) is the most prominent. It comes in monochrome and color varieties, the former getting extinct day by day. The display size is indicated as 14 inch, 15 inch etc., and the buyers guess the quality from the brand (Samsung, Microtek, Frontech etc.). The keyboard contains many keys for representing alphabets, digits, symbols etc. as well as for commands. Most of the keys has to be pressed in a light momentary stroke (immediate withdrawal of finger after pressing), while the three keys Shift, Ctrl (control) & Alt (alter) has to be kept pressed for a while till another key is momentarily pressed (with another finger). Keyboard comes in varieties such as 101-key, 104-key etc., but the best variety for an experienced user is the one with which she is conversant. A high speed in keyboard operation generally comes through a traditional finger training as is imparted in typewriting courses. Mouse is a device (made by Logitech etc.) that can be moved on a mouse-pad to change the position of the mouse-pointer in the VDU screen, and commands made by clicking any of its two or three buttons. External speakers have been already mentioned. Microphone can convert sound into electrical signals which then gets converted to computer data. Modems are devices that transform computer data to and from electrical signals moving in telephone wires, and are must for connecting to the internet. Printers (made by Epson, HP, Canon etc.) can print computer data on papers or transparent sheets etc., you'll learn much more about them on the 6th day. Modems (made by D-Link etc.) may be of the internal or external types, depending on whether they lie inside or outside the computer cabinet. The speed of a modem is expressed in Kbps unit (1 Kbps means 1000 bit i.e., 125 (= 1000/8) byte of data transferred per second), such as 33.6 Kbps or 58.6 Kbps, but if the possible speed of data transfer through the telephonic wire is smaller, a better modem would make no difference. The external modems are of two types that either require (traditional type) or don't require (newer, USB type) a separate power source. Scanners (made by HP etc.) are devices that can convert text or picture (by scanning it) on paper into computer data, its quality expressed in speed and resolution parameters. Digital camera are devices such that the photographs taken by them automatically become computer data. The interconnecting cables connect all these hardware parts with one another. The computer obviously need a stable and properly grounded (earthed) power supply with a stable voltage and stable frequency, therefore requiring a device such as an stabilizer or an UPS (uninterrupted power supply) along with preferably also a surge protector (also called a spike buster), as will be detailed on the 6th day.

The external hardware parts can be connected with the computer (cabinet box) by inserting the ends of the fixed cables coming out of those parts into the specific ports on the back of the cabinet box (obviously the power supply must REMAIN OFF when you connect or disconnect any cable). It's an advisable practice to indicate with pencil the name of the hardware part on a space near the proper port, so that when one or more computer part comes back after a repair, you would be able to correctly join it without calling an expert. Some ports such as those of microphone or speaker are simple, and the cable could be inserted or withdrawn just by pressing or pulling. Other ports such as that of VDU are complicated, and you need to rotate a pair of screws at the end of the cable to connect or to disconnect.

To turn the computer on, first ensure that the mains power supply is on, and that the UPS/ stabilizer and/ or surge protector etc. are on. If the monitor has a separate power switch, it must be turned on separately: in that case it is better turned on before the computer cabinet is turned on. Then the power switch of the computer cabinet is to be turned on. In a normal course, the computer gets ready for operation only within one or two minutes of being turned on, as during that period the mandatory self-tests etc. are done and the computer-operating software (called operating system e.g., Windows 2000) is loaded i.e., gets ready. This ready condition is observable from a particular appearance of the screen, such as the appearance of a stationary desktop with the well-known Start button at the extreme left-bottom corner in case of any of the Windows operating systems. However, after turning on, you may be asked to enter one or two passwords: in that case type in the password (s) as required, and press the Enter key. After using the computer, you need to shut down the operating system before turning the computer off. To do that in case of Windows, one clicks the left button of the mouse with the mouse-pointer at the start button, then clicks again with the pointer at the Shut Down option of the resulting start-menu, then clicks again with the pointer at the Yes option of a dialog box, and wait till Windows is shut down. After that, the power switch of the cabinet may get automatically turned off, or it has to be manually turned off, depending on the type of cabinet. If it gets automatically turned off, then manually pressing the switch (to turn that off) will do no good but rather will turn the computer on! If the monitor has a separate power switch, then it has to be turned off after that. After that, the UPS/ stabilizer and/ or surge protector has to be turned off, and the mains power supply cord disconnected from the plug, as is generally the norm in most households and institutions. The telephone wire connection to the modem etc. should also be disconnected when not in use. Such isolating disconnection of the computer from the outside world is a popular norm in India that helps in protecting the computer from lightning, which is one of its lethal enemies.

The computers nowadays are more robust than earlier ones, and so doesn't require air-conditioning in ordinary climates. Still, it should be kept in a relatively dust-free room, away from direct sunlight and heaters/ stoves etc., and dampness or spillage of water etc. is to be avoided. More generally, the computers get however, harmed on the software front, by maliciously intended programs known as virus, worms etc., most of which can propagate automatically (like their biological counterparts) from computer to computer through the internet, local computer networks, floppy diskettes, CDs and so on. To avoid getting harmed by viruses etc., (as the harm may range from deactivation or destruction of the operating system and/ or applications to the permanent loss of your own created data!), you need to have an anti-virus software (provided by Norton, McAfee etc. as priced product and grisoft.com, freeav.com  etc. as freeware) in addition to backing up (keep copies) of your created data and bought applications into floppies or CDs etc.. Furthermore, as new and newer viruses are being written every week by people with crooked minds, the anti-virus you're using must also have newer antidotes for newer viruses, and so your anti-virus software must be frequently updated, say once in a week. Such updating are generally provided free by the anti-virus firms to their registered customers, either through the internet or through CDs etc. provided with the computer periodicals (e.g., PCQuest from India).

Particularly because of improper shutdown of the computer and also due to hardware problems in the disk, some errors may occur in the hard-disk and also in floppy diskettes. To rectify this problem, an utility called scandisk is available. It can be run in two forms, the faster standard form and the time-consuming thorough form. Windows 98 and later operating systems can now automatically detect any need for an standard scandisk operation when starting the computer, relieving the user of this responsibility (you must allow the computer to thus finish taking care of itself, whenever it so decides). A monthly or bi-monthly performance of thorough form of scandisk is advisable for aged hard-disks that shows hardware problems, and if scandisk advises, you may need to replace an aged hard-disk or at least go for a backup (into CDs, floppies or internet) particularly of your created data (as hard-disk failure means an erasure of all your data and applications).

While working, the computer generally stores any large file in several fragments kept in different physical parts of the hard-disk. Thus accessing the file next time from the disk require longer time, slowing down operations that require disk access. This process is called fragmentation, and to prevent this an utility called Defrag (defragmentation) may be run. However, while run Defrag, you might lose more time than you gain in computer operations!

The floppy diskette drive head and the CD (or DVD) drive head come in contact with the removable floppies and CDs (or DVDs), and so in contact with external dust. So, there's a need of keeping them clean. There are floppy drive cleaning kit and CD-drive cleaning kit available in the market which may inserted into the drives, and then the drives activated in the ordinary way to let the cleaning take place. Depending on load of use, a weekly or monthly cleaning may be advisable. The floppy diskettes (and hard disks also), after their manufacture, undergoes a procedure called formatting that prepares them to store data: nowadays floppies are sold in the pre-formatted form. A formatting operation erases all pre-existing data, if any, in the disk or diskette. Still, formatting (particularly the full form) is used to turn floppies or hard-disks perfectly free from a deadly virus infection, or (in the quick form) to just erase all pre-existing data in one go.

The computer software that causes the visible hardware to work in the desired way to make a computer, may be divided in three broad classes: (i) operating systems such as Windows 98, Windows 2000, DOS, Linux, Unix etc. that run the computer hardware and the other software, (ii) application software such as Microsoft Word, WordPad, PageMaker, CorelDraw, Microsoft Excel etc. that perform user-oriented applications such as word-processing, picture manipulation, worksheet processing etc. (iii) language compilers such as those of Fortran, Visual Basic, C++ etc. that converts the codes (i.e., instruction-sets, also called programs) written in those computer languages to machine-executable files that can be directly executed by the computer.

Practical for Day 1 Course:
(1) Manage a computer guru with access to a present-day full-fledged computer with Windows (95/98/Me etc.).
(2) See and learn the computer cabinet (noting the removable disk drives and the LED lights) and the different external parts, and get idea of how the said drives and the external parts work. If possible (only if the guru can), con the guru to open the cabinet and show the internal parts inside that.
(3) Learn how to disconnect and connect (only if the guru can) the cables to the different kinds of ports, and the power cables to and from the UPS/ stabilizer.
(4) Learn the process of safely turning the computer on and off, and also of turning the power supply off & on.
(5) Observe the guru working on the computer, particularly how the keyboard and the mouse is operated on.
(6) See demonstration of the following activities: (a) Virus Scanning (b) Scandisk operation (c) Defrag (d) Cleaning of Floppy Disk Drives and Compact Disk Drives (e) Formatting of Floppy Diskettes.
(7) Collect an specification of computers presently popular in the market, available even in newspaper advertisements. If you didn't understand any term in that specification, clarify from the computer guru.