1.1 systems architecture Flashcards
Input examples
Keyboard, mouse, touchscreen, microphone, game controller
Output examples
Speaker, printer, projector, screen
Purpose of the CPU
Fetch, decode and execute instructions
What is/what happens during fetch
Fetching the next instruction from the min memory (RAM)
Brings the instructions back to the CPU
What happens during decode
Inspects the instruction and works out what needs doing
What happens during execute
Carries out the instruction
What does the ALU (arithmetic logic unit) do
Performs calculations and logical decisions
What does the CU (control unit) do
Sends signals to control how data moves around the CPU
What does cache do
Provides fast access to frequently used instructions and data
What do registers do
They’re tiny, super fast pieces of onboard memory inside the CPU with very specific purposes
What did john von Neumann do
Developed the stored program computer. Both programs and data are stored in memory
What the the PC (program counter) do
Holds the address of the next instruction in memory
What does the MAR (memory address register) do
Holds the address of where data is to be fetched or stored
What does the MDR (memory data register) do
Holds the data fetched from, or to be written to memory
What does the accumulator do
Holds results of calculations
What is clock speed
An internal clock that happens on the pulse. If it increases then introductions are processed faster
How does clock speed affect the CPU performance
Doubling clock speed will double the number of instructions executed per second
What is cache size
Fast and small amount of memory that holds commonly used instructions
How does cache size affect the cpu performance
Increasing it reduces number of visits to RAM so may speed up processing these instructions
What’s number of cores
Where instructions are executed, processors can have multi-cores. Each one executes instructions independently. Dual cores MAY execute up to twice as many instructions per second
How does number of cores affect CPU performance
Quadrupling the number of cores MAY quadruple the number of instructions executed per second
What’s an embedded system
A computer system with a specific function within a larger mechanical space
Characteristics of embedded systems
Task specific
do the same task repeatedly & continuously
Task is performed in a certain time frame
Basic no user interface
Some respond to external stimuli using sensors
Embedded system examples
Dishwasher
Sat nav
Washing machine
Thermostat
