1.1: Systems Architecture Flashcards
What is the difference between hardware and software?
Hardware is a physical component of a computer, software is a program that runs on a computer
Draw a basic computer system model
Input with arrow to CPU
Memory and secondary storage with 2 way arrows to CPU
Output coming from CPU
Name 4 input devices
Mouse and keyboard, microphone, camera, thermistor
Name 4 output devices
Speaker, monitor screen, printer, actuator
Name the 2 main functions of the CPU
To process data and information
To control the rest of the computer system
Name 5 functions of the control unit (CU)
. It controls the execution of instructions in the correct sequence
. It decodes instructions
. It regulates and controls CPU timing using regular pulses
. It sends and receives control signals to and from other hardware pieces within the computer
. Controls data movement
What is the function of the arithmetic logic unit?
It performs logic operations, shift operations and arithmetic operations
What is the cache?
A small amount of fast RAM which provides fast access to frequently used instructions and data
What does the clock do?
Sends out electrical pulses at regular intervals to synchronise the components of the computer.
What is a register?
A small amount of high speed memory used to store small amounts of data that are needed during processing
What is an address?
The location of a piece of information
What does the program counter (PC) do?
Holds the memory address of the next instruction to be processed
What does the memory address register (MAR) do?
Holds the address of where data is to be fetched from or stored into
What does the memory data register (MDR) do?
Holds data or an instruction temporarily after it has been fetched from memory or about to be sent to memory
What does the accumulator (ACC) do?
Temporarily holds the result of operations carried out by the ALU
Describe the process of the fetch stage in the fetch-execute cycle
Program counter is checked for address of next instruction. The address is used by the MAR to fetch the instruction from the main memory and bring it back to the MDR. PC looks for next address.
Describe the process of the decode stage in the fetch-execute cycle
Now the instruction is in the CPU, the CU decodes the instruction to see what has to be done
Describe the process of the execute stage in the fetch-execute cycle
The instruction is carried out. What is done depends on the instruction, such as fetching data from the RAM and adding it to the accumulator or writing data in the accumulator into RAM
What are the 3 main stages of the FE cycle?
Fetch, decode, execute
What 3 main factors affect the CPU’s performance?
Clock speed, cache size, number of cores
What does an increase in clock speed do to the CPU?
Increasing the clock speed increases the number of instructions processed/cycles per second
What is clock speed measured in?
Hertz
What is the average clock speed for a PC?
Between 2GHz and 4GHz
What happens to CPU performance when cache size is increased?
The more data and instructions can be held in cache and made available quickly, increasing processor performance
