Notes from Book for chapter 2

What Computers Do:
- There are 4 basic functions of a computer

1. Recieve Input: comps accept info from outside world
2. Process Info: Comps form arithmetic and logical operations on info.
3. Produce output: comps comm. info. to the outside world
4. Store info: Comps move and store info. in memory

FOUR FUNCTIONS

Input devices: accept input from outside world
Examples are: keyboards and pointing devices (mouse)

Output devices: send info to outside world.
Examples: video monitor or printer

Microprocessor: the "brain" of the comp

Memory and Storage Devices: both store info. but they serve diff purposes

BIT BASICS:

Digital is made up of digits

Bit (binary digits): the smallest unit of info. a comp. can process

BUILDING WITH BITS:
~ Bits as Numbers

binary number system: a system that denotes all #s w/ combinations of 2 digits.

~ Bits as Codes:

ASCII ( American Standard Code for Information Interchange): represents each character as a unique 8-bit code.

Unicode: a coding scheme that supports 65,000 unique characters.

BITS, BYTES, AND BUZZWORKS:

Byte: a group of 8 bits. ( one character of ASCII)

Kilobyte (KB or K): 1,000 bytes of info.

Megabyte or meg (MB): app. 1,000KB  or 1 millionbytes

Gigabyte (GB or gig): app. 1,000MB or 1 billion bytes

Terabyte (TB): app. 1 million MB or 1 trillion bytes.

Petabyte (PB): is equivalent to 1,204 terabytes or 1 quadrillian bytes.

file:  is an organized collection of info.

megabits (Mb): used to measure data to transfer speed or memory size.

THE CPU: THE REAL COMP.

microprocessor: (CPU) an extraordinarily complex collection of electronic circuits.

motherboard: the circuit board that contains a comp's CPU.

COMPATIBILITY:

Compatible: software written for one processor will usually not work with another.

Backward Compatible:

PERFORMANCE:

clock: the timing device that produces electrical pulses to synchronize the comps operations.

gigahertz (GHz): billions of clock cycles per second.

architecture: the design that determines how individual components of the CPU are put together on the chip.

Cluster: the name of the processing resources of multiple serveers all grouped together.

-multicore processors
-Parallel processors
-symmetric multiprocessing
-multiprocessing

THE COMPUTER'S MEMORY:

nonvolatile memory: the comp can read from it, but it can never write any new ifo. on it

read-only memory (ROM): wat the nonvolatile memory is called sometimes.

1. Complementary metal oxide semiconductor (CMOS): is a special low- energy kind of RAM that can store small amounts of data for a long period of time on battery power.

- CMOS RAM store date, time, and calender, in a PC

     2.  Flash Memory: are chips, like RAM chips, that can be written and erased rapidly and repeatedly. But unlike RAM, a flash memory is nonvolatile., it can keep its contents without flow of electricity

-Examples are: digital cameras, cell phones, pagers, PDA's, handheld comps, portable comps, etc.

access time: measured in nanoseconds (ns) billionths of a second

millisecond (ms): thousandths of a second.

- Memory speed (access time) is another factor that affects the comp's overall speed

BUSES, PORTS, AND PERIPHERALS:

system buses (buses):groups of wires in the motherboard

bays: type of storage devices

Ports: sockets on the outside of the comp chassis.

PC cards: cards that contain memory, mini peripherals, & additional ports.