1. Computer Systems
Computer
Systems

2. A computer is . . . A purely digital device
Definition: Digital is a type of electronic signal that is processed, sent and stored in bits—binary digits
Computers use binary coding—a coding system that uses two numbers--1 & 0
In computer terms, the bit is the smallest unit of measurement a computer can understand

3. Bits to bytes . . . 8 bits equal 1 byte
A byte is a single character of data, such as a letter, number, etc.
Term
Abbreviation
Approximate Size
Kilobyte
KB or K
=1000 bytes (actual size is 1024 bytes)
Megabyte MB
=1 million bytes
Gigabyte GB
=1 billion bytes
Terabyte TB
=1 trillion bytes

4. Computer systems
The physical components of a computer system are called hardware.
Hardware typically includes:
System unit, monitor, keyboard, mouse
Peripheral devices (extra) such as a printer or scanner

5. Computer system vs. System unit
Computer system—the system unit along with input and output devices
System unit—the part of a computer system that processes data and stores information

6. Computer systems Embedded Smartphone Tablet Laptop Desktop Server
Mainframe
Super
Wearable

7. System unit The main circuit board of a computer is the motherboard.
The central processing unit is located on the motherboard. The CPU is the circuitry that processes information—the “brain” of the computer.
The speed of the processor is controlled by the system clock.

8. System clock
Controls the timing of ALL computer operations; measured in hertz—one cycle (tick) per second. Speed is measured in gigahertz (GHz)—a billion cycles per second.
It takes about one-tenth of a second to blink your eye; a computer can perform some operations 10 million times in the time it takes you to blink you eye.

9. The most popular brand processors on the market are AMD and Intel.

10. Memory:
Main memory is located on the motherboard. It is also known as primary storage.
Random Access Memory (RAM): Volatile memory available to the user; typically measured in Gigabytes.
Read Only Memory (ROM): non-volatile memory that handles basic computer functions known as BIOS: Basic Input/Output Systems.

11. Input Devices:
Any hardware component that allows a user to enter information into a computer
Keyboard
Pointing Devices
Scanners
Multimedia

12. Pointing devices: Mouse Trackball Touch pad—typically found on laptops
Pen input—pen-like device touches surface of screen to digitally input data
Touch screen—touching the screen with your finger digitally inputs data

13. Scanners Bar code reader—reads universal product codes (UPC)
Computer Systems
Scanners
Bar code reader—reads universal product codes (UPC)
Optical mark reader (OMR)—reads “bubble” sheets marked with pencil
Optical character reader (OCR)-reads handwritten or typed text
Page scanner—digitally captures an image or text
The second bar code is actually a QR (quick response) code, which is a variation of a bar code.
2d CODES:

14. Multimedia Microphone Electronic music keyboard Video camera
Digital camera
Virtual reality devices

15. Output device
Any hardware component that can convey information to the user
Display devices (soft copy: data projected on a screen)
Printers (hard copy: data printed on paper)
Speakers

16. Display devices 360° Projector HDTV Pico Projector Flat-Screen Monitor
Document
Projector
Interactive
Whiteboard
HDTV
Pico Projector

17. Printers The two most common types of printers are ink-jet and laser
The speed of a printer is measured by the number of pages per minute (PPM) that can be printed
The quality of a printer is measured by the number of dots per inch (dpi) that can be printed

18. Storage devices The media on which data and information are kept
Three classifications:
Magnetic—hard disk
Optical—CD, DVD, Blu-ray
Information is burned on the disk by laser
Flash—memory cards, flash drive

19. Communication devices
Devices that make it possible for a user to communicate with another computer
Most popular: modem
Phone, cable, DSL
Computers on a network use network interface cards (NIC)
Wired or wireless