System Architecture Flashcards
What are the stages of the FDE cycle?
Stage 1: Fetch
Stage 2: Decode
Stage 3: Execute
What is RAM?
The main memory
What happens in the fetch stage of the fetch-execute cycle?
- The program counter is checked as it holds the address of the next instruction to be executed.
- This address is used by the MAR to fetch the instruction needed from RAM and bring it back to the CPU
- The address in the program counter is incremented to point at the next instruction
What happens in the decode stage of the fetch-execute cycle?
The CU decodes the instruction and works out what needs to be done
What happens in the execute stage of the fetch-execute cycle?
The instruction is executed with could be
- Going back to the memory and grabbing some data
- Performing a calculation
- Storing information back into main memory
What is clock speed measured in?
Hertz (Hz)
1 hertz (Hz) means…
…one cycle per second
CPU stands for
Central processing unit
What is an input device?
A device used to enter information into a computer
What is an output device?
A device that presents data from the computer
What is a storage device
A piece of computer equipment on which information can be stored
What is the CPU?
The part of the computer that fetches, decodes and executes instructions and manages the rest of the hardware
Describe The Von Neumann Architecture
- Instructions are fetched, decoded and executed once at a time
- Instructions and data are held together in the same memory space
What does the address bus travel between?
MAR to RAM
What does the data bus travel between?
MDR and RAM
What does the control bus do?
Carry signals to coordinate all the computer’s activities
What does CU stand for?
Control unit
What does the CU do?
- Decode instructions
- Send control signals to control how data moves around the CPU
What does ALU stand for?
Arithmetic logic unit
What does the ALU do?
Carry out mathematical and logical operations
What are special purpose registers
Small amounts of high speed memory used to store small amounts of data needed in proccesing
What does MAR stand for?
Memory address register
What does the MAR do?
Holds the address of where data is to be fetched or stored
What does MDR stand for?
Memory data register
What does the MDR do?
Holds data fetched from or to be written to the memory
What does the program counter do?
Holds the address of the next instruction
What does ACC stand for?
Accumulator
What does the accumulator do?
Hold the results of calculations performed by the ALU
What is the cache?
Memory that provides fast access to frequently used instructions and data
What are the factors affecting the speed of the CPU?
- Clock speed
- Number of cores
- Cache size
What did John Von Neumann invent in 1945?
The first computer with a stored program
What is a fixed program?
A program that cannot be updated without rewiring or redesigning
What is a core
A complete copy of the CPU
What are embedded systems?
Computer systems with a dedicated function within a larger mechanical or electrical system
What are the advantages of multi core processors?
- Cores can work on separate tasks at the same time (multitasking)
- The cores can work together (parallel processing)
How does a bus transport data across the motherboard?
With electrical conductors
What is another name for the FDE cycle?
The instruction cycle
What is clock speed?
The frequency at which the internal clock generates pulses
What does the internal clock do?
Synchronises components by generating pulses at a constant rate
Why does cache size affect the speed of the CPU?
The larger the cache, the more data can be stored without having go back to RAM
