Key Area 1.4 - Low Level Operation and Structure Flashcards
What is the control unit
This sends control signals which allow data to be stored in memory, fetched from memory and which decode and carry out instructions
What is the ALU
The arithmetic and logic unit
This carries out all of the computer arithmetic (addition subtraction multiplication) and logical (IF AND OR =) functions
What are the registers
The storage locations that are internal to the processor
They are used to store data that is being transferred to and from memory and hold the addresses of the location in memory which the processor is accessing to read or write data. It holds the instructions that are currently being carried out
What is main memory
Main memory can be either rom or ram
ROM is system memory which holds the system information
RAM is the working space of the computer and holds all the data and files currently in use by the system
Give the properties or RAM
Random Access Memory
The processor can read to or write from RAM quickly
Data held here can be edited
Data held here is lost when the power is turned off
RAM holds all the data and programs currently in use
Give the properties of ROM
Read Only Memory
Data here cannot be edited and is stored permanently
Data us nit lost when the power is turned off
Holds vital system data and programs
What is a bus
Buses are used as transmitters between different parts of a computer system
What is the data bus
The data bus is used to carry data to and from the CPU and memory. Each line on a data bus will carry one binary word
What is the address bus
The address bus holds the memory location of where data is about to be stored or from which data is about to be read
What is the control bus
The control bus is a series of independent control lines used to send out control signals such as
Read from
Write to
What is the fetch execute cycle
The computers memory RAM stores the program and data instructions while they are being used
The processor then decides and carries ur each program instruction
These instructions often involve fetching and processing the data stored in memory
What is an interface
An interface is the combustion of hardware and software needed to link the processor to the peripherals and is the means by which independent systems can communicate They can Change electrical voltages Deal with control signals Change analogue data into digital data Store incoming data
What is ASCII
American Standard Code for Information Interchange
Holds 8 bits therefor 256 characters
What is Unicode
Contains every character based alphabet, ideographical languages, punctuation and control signs
Show the progress of memory size
Bit Byte Kilobyte Megabyte Gigabyte Terabyte
What is machine code
The language that the computer understands at the lowest level. This is very difficult to read.
Programs written in high level languages must be translated into machine code
What is an interpreter
An interpreter does not produce object code
The translator translates and executes each line of code in turn
Advantages
Any errors present are highlighted immediately and easier to fix
They can run code still being developed
Disadvantages
The translation is not saved and therefor must be rerun each time the code is run
If a loop is present the code is translated and run many times
Individual runs are slower
What is a compiler
A compiler translates source code into machine code. Once the code is translated it is stored and does not have to be translated again
Advantages
If no errors are found the source code does not need to be translated again
Disadvantages
If any syntax errors are present the program won’t run
The errors are harder to correct as they are not identified until the code is translated
What is floating point representation
It is used for real numbers which are numbers with a decimal portion
Only the mantissa and exponent are stored, the base is implied saving storage space
How are bit maps stored
Made up of small squares of colour (pixels)
How are vector graphics stored
Each object in the picture is described mathematically as a list of attributes
What is the processor
The processor is at the centre of all of the computers operations and deals with all the movements of data and any calculations to be carried out. Composed of the
Control unit
ALU
Registers
