1.1 architecture of the cpu +1.2 memory and storage Flashcards
what is the fetch cycle in the fetch-decode-execute cycle?
An instruction is fetched from main memory (also known as RAM) and brought back to the CPU
what is the decode cycle in the fetch-decode-execute cycle?
The instruction is then decoded to find out exactly what needs to be done
what is the execute cycle in the fetch-decode-execute cycle?
The instruction is then carried-out (e.g. a calculation is performed)
what is the control unit?
Controls the flow of data from the CPU to and from other devices (such as the main memory)
Keeps the computer synchronized using the clock
what is the arithmetic logic unit (ALU)
Carries out arithmetic (such as binary addition) and logic (such as comparing numbers) operations
what are the registers of a cpu for?
The fastest memory locations in a computer
Used to store instructions and data currently being used by the CPU
what is the cache of a cpu?
Second fastest memory location in computer (after the registers)
Used to store data/instructions about to be used, or frequently used by CPU (faster than getting from main memory/RAM)
what is the von neumann architecture?
Instructions and data are both stored in the same place - the main memory (RAM) - we call this Von Neumann architecture
Instructions are fetched from the memory and processed by the CPU one at a time
what is the program counter?
Holds the address of the next instruction to be fetched from the memory
what is the memory address register (MAR)
Holds the address in memory where data will be fetched/stored
what is the memory data register? (MDR)
Holds the actual data that was fetched from memory or that will be stored in the memory
what is the accumulator?
Holds the results of calculations
what is clock speed?
The CPU clock dictates how fast the FDE cycle happens.
If the clock speed is increased, more FDE cycles can be completed per second.
If more FDE cycles are completed per second, more data can be processed per second
what is an embedded system?
An embedded system is a computer which is built-in to another device to complete a specific task
e.g a washing machine
what is ascii?
he ASCII character set is able to store:
The letters used in most European languages (English, French, German, Spanish,….)
The digits 0 - 9
Common punctuation symbols (!,?,&,%,….)
Standard ASCII uses 8-bits (1 byte) binary values.
(00000000)
So ASCII can store 256 different characters in its character set. (0 – 255 gives a range of 256)
what is unicode?
Uses 16 bits (2 bytes) binary value for each character. It can represent 65,536 different characters (216 = 65,536).
Enough values to allow us to represent alphabets used in many writing systems.
what are bitmap graphics?
Images are made up of coloured blocks called pixels (short for picture elements)
what is resolution?
the number of pixels within a defined area
measured in dots per inch (DPI)
what is bit depth?
The number of bits used to store the colour of each pixel.
the number of bits squared is the amount of colours in the image
how do you calculate file size?
the rows x the columns gets the pixels, then you do the number of pixels x the bits per pixels
how do you calculate the file size of sound?
File size (bits) = sample rate × duration x bit depth
what is lossy compression?
Some of the data is permanently removed from the file
Advantages: Larger reduction in file size
Disadvantages: Loses some quality as you can’t get back the removed data. Not suitable for all types of data
what is lossless compression?
Some of the data is temporarily removed from the file
Advantages: No loss in quality as as the data removed can be retrieved. Suitable for all types of data
Disadvantages: Smaller reduction in file size
