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Version 1.0
devices other than the system unit
sound card
display / graphic card
units
GB
MB
KB
byte - 8 bits
bit
the smallest / basic computer storage unit. It stores eithe a 0 or a 1.
secondary storage
storage devices which are not the main memory all fall into this category.
semi-conductor
USB thumb drive
flash memory card
xD
Memory Stick
SD
CF
optical
DVD
CD
magnetic
magnetic tape
Mainly for server backup.
harddisk
The major secondary storage device.
floppy
printer
ppm (page per minute) - speed
dpi (dot per inch) - quality
speaker
monitor
pixel
color depth
Number of colors can be displayed. Usually measured in bit. For example, 4-bit color means 2^4 = 16 colors.
resolution
The number of pixels can be displayed. There are many standards, for example , VGA, SVGA, XGA etc.
barcode reader
scanner
biometrics
the use of personal characteristics / features to identify a computer user. In that way, people don't need to remember their computer passwords as they use their body traits as passwords.
iris recognition
finger print
pointing
track ball
touch pad
mouse
CMOS
1. non-volatile
2. store system information (e.g. date, harddisk info, RAM info etc)
3. data inside it can be updated/ changed.
ROM
stores:
1. S (Basic Input Output System) - a program to be loaded into RAM for checking the computer hardware configuration
2. Boot program - a program to start the computer
Characteristics:
1. store permanent instruction
2. read ony / can't be written
3. small in capacity
4. non-volatile
RAM
1. volatile - loss data when power off
2. store temporary data and instructions to be used by CPU
3. upgrade - memory capacity can be changed
ports 連接埠
DVI
VGA
LAN
PS2
USB
bus 總線
slots
performance factor
word length字長
It means the number of data that can be processed at one time. Usually measured in bits, for example, 16-bit, 32-bit and 64-bit.
clock speed時鐘頻率
e.g. 2.8GHz
2.8GHz means in a second there are 2.8 billion instruction cycles.
the faster the better
Hz
1 instruction cycle
cache快取記憶體
fast memory unit located inside CPU to store frequently used instructions and data for the CPU. Compare to RAM, it is
1. faster
2. small in capacity 容量較RAM少 (usually measure in MB)
3. more expensive
Arithmetic Logical Unit
Control Unit
Application software refers to programs that help users get their works done by using the computer. The list is only a small sample.
System sofware refers to programs which make your computer works.
programs which helps an OS to communicate and manage a peripheral device.
programs to maintain your computer's health and improve the computers performance.
examples
Screen Saver
System optimizer
Encryption
Data Recovery
Data Compression
Disk Defragmentation
Anti-virus
Functions:
1. allocate system resource
2. manage files
3. monitor activites
User Interface用戶介面
Graphical User Interface (GUI)
1. easier to learn and master
2. consume a lot more system resource
3. works slower
Command Line Interface (CLI)
1. need less system resource
2. difficult to learn and master
3. works faster
types
multi user
several users can be using the same computer or even the same program on that computer at the same time.
single user
only one user can use the computer at a particular time.
multi tasking
be able to handle multiple tasks at the same time.
single tasking
be able to handle ONE task at a particular time.
example
Linux
Apple OSX
Windows
