CS 223 What is a Computer

A computer consists of what 7 things

CPU, memory, hard disk, floppy disk, monitor, printer, and communication device

A _______also uses a phone line and can transfer data in a speed 20 times faster than a regular modem.

DSL (digital subscriber line)

_____ of various kinds, such as numbers, characters, and strings, are encoded as a series of bits (zeros and ones). Computers use zeros and ones because digital devices have two stable states, which are referred to as zero and one by convention. The programmers need not to be concerned about the encoding and decoding of data, which is performed automatically by the system based on the encoding scheme. The encoding scheme varies. For example, character 'J' is represented by 01001010 in one byte. A small number such as three can be stored in a single byte. If computer needs to store a large number that cannot fit into a single byte, it uses a number of adjacent bytes. No two data can share or split a same byte. A byte is the minimum storage unit.

Data

________ is to store data and program instructions for CPU to execute. A memory unit is an ordered sequence of bytes, each holds eight bits. A program and its data must be brought to memory before they can be executed. A memory byte is never empty, but its initial content may be meaningless to your program. The current content of a memory byte is lost whenever new information is placed in it.

Memory

Output Devices: _______ The monitor displays information (text and graphics). The resolution and dot pitch determine the quality of the display.

Monitor

A _______uses the TV cable line maintained by the cable company. A______ is as fast as a DSL. Network interface card (NIC) is a device to connect a computer to a local area network (LAN).

cable modem

The ________ is the brain of a computer. It retrieves instructions from memory and executes them. The CPU speed is measured in megahertz (MHz), with 1 megahertz equaling 1 million pulses per second. The speed of the CPU has been improved continuously. If you buy a PC now, you can get an Intel Pentium 4 Processor at 3 gigahertz (1 gigahertz is 1000 megahertz).

central processing unit (CPU)

Program called a ______ is used to translate the source program into a machine language program called an object program. The object program is often then linked with other supporting library code before the object can be executed on the machine.

compiler

The ____ ____ is the amount of space between pixels. The smaller the dot pitch, the better the display.

dot pitch

The ________ is a program that manages and controls a computer's activities. You are probably using Windows 98, NT, 2000, XP, or ME. Windows is currently the most popular PC operating system. Application programs such as an Internet browser and a word processor cannot run without an operating system.

operating system (OS)

Programs are written using ______ ______

programming languages.

A _____ _____ uses a phone line and can transfer data in a speed up to 56,000 bps (bits per second).

regular modem

the ______ specifies the number of pixels per square inch. Pixels (short for "picture elements") are tiny dots that form an image on the screen. The resolution can be set manually. The higher the resolution, the sharper and clearer the image is. However, the image may be very small if you set high resolution on a small screen monitor. PC monitors are usually 15-inch, 17-inch, 19-inch, or 21-inch. For a 15-inch monitor, a comfortable resolution setting would be 640480 (307,200 pixels).

resolution

Computer programs, known as _______, are instructions to the computer.

software

A program written in a high-level language is called a _______. Since a computer cannot understand a source program.

source program

Memory is volatile, because information is lost when the power is off. Programs and data are permanently stored on _______ and are moved to memory when the computer actually uses them. There are three main types of storage devices:Disk drives (hard disks and floppy disks), CD drives (CD-R and CD-RW), and Tape drives.

storage devices