Systems Flashcards
Two main types of translators
Compiler
Interpreter
Compiler
A compiler translates a complete high level program by converting every instruction into machine code before it executes the program.
Interpreters
An interpreter translates a high level language program one line at a time then performs the high level command. This is repeated until the whole program has been interpreted.
Compiler Advantages
- Only translate once
- Immediately available for use
- Runs faster than interpreted programs
- Can be loaded and executed on other computers which do not have the translator programs
Compiler Disadvantages
- Program errors are only detected when the program is compiled
- Development of programs is awkward as the whole program has to be compiled before it can be run
Interpreter Advantages
It error checks each line of a program as it is written which is useful for people learning to program
Interpreter Disadvantages
- The program has to be translated every time it is executed
- Runs slower than compiled programs
How many bits are in a byte?
8
01100110
102
67
01000011
What is the Mantissa of 0.75843 x 10³
75843
What is the exponent of 0.75843 x 10³
3
How are real numbers stored
Floating point representation - Mantissa and Exponent
How is text stored in the computer?
ASCII
8 bits
Each character has its own 8 bit number
What does ASCII stand for?
American Standard Code for Information Interchange
Vector Graphic Shapes
- Rectangle
- Ellipse
- Line
- Polygon
Vector Graphics Attributes
x/y co-ordinates
Fill colour
Line colour
Vector Graphics Advantages
- Do not lose quality when scaled
- Require less storage space
- Objects are easily moved/manipulated
- Resolution independent
Bitmap Graphics Advantages
- Can be manipulated at pixel level
- Can create a wide array of graphic effects
- Can represent photo-realistic images
Bitmap Graphics Disadvantages
- Requires large storage space
- Image becomes jagged when scaled
The two types of main memory
RAM (random access memory)
ROM (read only memory)
RAM
Random Access Memory
The computers short term memory
It’s volatile - when power is lost, contents of RAM are also lost
ROM
Read only memory
Always retain it’s memory even when power is lost
Used by mobile phones to store operating systems
Backing Storage
Used to store permanent copies of our files
Examples: Hard Disk Drives, USB Flash Drives, Magnetic Tapes, CD/DVD
Input Devices
Enters data into the computer. eg. keyboard and mouse
Output Devices
Generate output from the computer. eg. printer
What are the different parts of the processor?
Control Unit
Arithmetic and Logic Unit (ALU)
Registers
Control Unit
This controls the order of execution and the timing of instructions
Arithmetic and Logic Unit (ALU)
This performs the calculations for the processor . It also carries out the logical decisions.
Registers
These are temporary stores of information, at best they will store a few bytes of information.
Data Bus
The data bus is used to carry data to and from the CPU and Memory
It will hold a binary word
Address Bus
This carries the address of the memory that is being used
What is a bus?
A bus is a collection of wires which can carry data
Name 3 Security Risks
Viruses Worms Trojans DOS (Denial of Service) Attacks Spyware Keylogging Phishing Identity Theft Online Fraud
Name 3 Security Precautions
Anti-virus software Passwords/encryptions Biometrics Security Protocols and Firewalls Use of Security Suites
Firewall
Used to stop hackers and viruses from accessing a computer
Name 2 uses of firewalls
Check that incoming packets meet specific rules before beings allowed in.
Set rules about which stations on a network can send or receive packets.
Rules are created that take account of the following:
- Sender IP Address
- Receiver IP address
- port numbers
- protocols
Carbon Footprint DONT NEED TO KNOW THIS SULA
The measurement of greenhouse gasses produced from the manufacture, and the use and disposal of computing equipment
Negative effects of using computers
Raw materials and energy used to manufacture computing equipment, including smartphones
Energy used to power laptops, desktops, mainframes and servers
Internet use is increasing all the time. As it increases so does power consumption
Positive effects of using computers
Most manufacturers are now producing devices with low-energy consumption
Many workers now telecommute
Save paper by using digital instead of hardcopies
3 ways to reduce energy use
Change settings of your monitor
Change the power settings - energy saver
Set computer to automatically power down at the end of the day
Leave computer on stand by
What should you do with the hard disk if the computer is to be scrapped and why?
Shred it to prevent identity theft
Why is data encrypted before sending?
Prevents unauthorised access
Scrambled to make data unreadable
How is a bit-mapped graphic represented in a computer system’s memory
each pixel is stored as a binary value
