COMPUTER NOTES: HARDWARE
Hardware vs. software---Hardware you can touch: the screen, printer, keyboard, discs. Software is what controls the hardware. The computer speaks a very different language. Software is like a translator. Software or programs are written by a computer programmer in a code the computer understands. The very basic code is only 2 signals, ON/OFF. Zero and One. That is all the computer really understands, electrical pulse on or off. Names of computer codes or languages are: Machine, BASIC, Fortran, C, Visual Basic, HTML and many more. The code is put together into a program to do a task, such as a game, a word processor, run the printer, multiply or divide, start the computer, etc. All softwares translate or make it easy for us humans to communicate with the hardware needed. See Page 4 - HTML code for a web page.
THE COMPUTER IS MADE UP OF LOTS OF COMPONENTS
1. CPU or central processor unit: The brains!! Outwardly, just a big metal box, laying horizontally, or vertically, called a tower. Inside, chips, transistors, capacitors, wires, flat wires, cards, disc drives, fans, connections. Rated by speed of the processor chip. Early the chips were named 286, then 386, with slow CPU speeds, small memories and small hard drives. Used an operating system (DOS) that you commanded the computer (by typing commands) to do things, like start a program, stop a program, print something, shut down. Now we have Pentium chips that run as fast a 50 Giga bytes. My computer at home is a 300 Mega byte system. Now we have the Windows system. You click on icons which get the programs, etc. to run or shut down or do things. (KB = Kilo or 1000 bytes, MB = Mega or 1 million bytes, GB = Giga or 1 billion bytes) My son’s 1st computer had 2000 bytes and no keyboard. He had to communicate with it by changing switches. The output screen had room for 8 letters at a time.
2. RAM: temporary storage or memory. When you close a program or shut down the computer, RAM memory is cleared. Today, 128 KB of memory chips is getting to be normal, the programs have gotten so complicated, so large.
3. Hard drive: Permanent memory storage. Up to 50 GB. Info stays in memory on the disc when shut down.
4. Floppy disc drive: 3.5 inches now. Used to be 5.25 inches. Permanent storage before hard drives. Used to move files between computers. 5.25 stored about 360 KB. 3.5 stores about 1.44 MB.
5. CD drive: Permanent storage memory, now mostly used to enter new programs to your computer. Many programs store lots of data on your computer, but you have to have the CD in the drive for the whole program to work properly. Can store 100 times more that a floppy. All CDs contain 0 or 1’s.
· CD ROM: for storage or transfer programs Can’t be used on your entertainment center.
· CD: usually sold with music or audio. Can’t change the data on the disc.
· DVD: Music and video. Becoming the replacement for the floppy drives.
6. Modem: Modulator Demodulator, translates the digital info from the computer to analog signals/tones for use on the telephone system. Current speeds are 56000 BPS or bits per second. The actual speed varies because of the modem, traffic, your computer, telephone system, the other end modem, etc. Now being challenged by cable modems or DSL modems, both called broadband, much higher transfer speeds. This Modem is what connects you to the telephone system and the outside world wide web. Can be on an inserted board or an external case.
7. Connections: A computer has many systems inside to allow you to connect to peripheral/outside equipment.
¨ Telephone-one in and one out connection-on the modem board
¨ Printer-usually WYSIWUG- can be black ink or colored ink. Ink jet, bubble jet, dot matrix
¨ Camera-to download pictures
¨ Scanner-to copy print or pictures. Can be used to change the print into actual word processor bits rather than just a picture of letters. Called OCR or Optical Character Recognition.
¨ Joystick for games-usually connect to the video board-on sound card
¨ Monitor-needs a special electrical video board-
· Normal is a 15 inch screen. More often a 17 or best a 19 inch screen is purchased.
· The monitor is a hi tech TV screen without the ability to tune a station. The monitor only has one station-the computer.
· It has more pixels to make a sharper picture. A pixel is one dot of color. Our eyes don’t see the dots, only collections of dots and so we see the picture.
· Cheap monitors usually have low resolution. Low resolution can only show 16 colors. The average nowadays is a 640 by 480 resolution.
· Some high resolution screens have 1024 x 768 pixels or better. High res can show up to 16 million colors.
· Resolution is measured across and down, i.e. 640 x 480, is 640 pixels across the screen and 480 pixels vertically.
¨ Keyboard-Several groups of multipurpose keys.
· Function keys are usually across the top. Various uses, each computer or program sets them up differently.
· Cursor control: Usually off to the right. 4 arrows to move the cursor during typing, plus others like Home, End, Page up, Page down, etc.
· Numeric key pad: Usually to the right, set up like a calculator keypad. Easier to use that the numeric keys on the regular key board. It also has a switch to change the use of the keys.
· Alpha/numeric keys. Just like a typewriter. Few additions: CTRL or control, ALT or alternate, ENTER—replaces the carriage return-plus.
¨ Mouse-has a ball under it to roll.
· Has 1 to 3 buttons and maybe a wheel. Some mice for CAD have 32 buttons. Some are connected by infrared or radio, no wires.
· The left button is used the most, it is just like the ENTER key. The right button gives lots of good choices, most of the time.
· When we use the button on the mice, we say we CLICK. Clicking is a 3 step process: A. you place your pointer/cursor where you want it on the screen, B. then push a button and C. release it
· The pointer on the screen is a non-blinking arrow. The tip of the arrow is the sensitive or hot spot. When ready to insert some text, and you have CLICKed the mouse, the pointer turns into a CURSOR. It is shaped like a capital I or a straight bar | and it always blinks when it is placed on a page. The cursor can be moved with the cursor arrow keys or the HOME or END or the Page up or down keys.
¨ Speakers-need a special electrical sound board
¨ Microphone-not always included-connects to sound board
¨ Removable HD-not a necessity
¨ Networks-needs a special electrical network (NIC) board. Used to connect many computers together, like in an office. Everybody can intercommunicate or have joint use of software, storage, printers, internet, modems, etc. Networks are like miniature internets without the modem. They are hard wired, i.e. cables from one computer to the other through a server computer or router.