1.1- Systems Architecture Flashcards
Von Neumann
Computing pioneer from Hungary who gave his name to a computer architecture that uses stored programs. Instructions are fetched, decoded and executed one at a time.
Fetch
The phase of the instruction cycle that retrieves an instruction from main memory
Decode
This phase of the instruction cycle determines what task the CPU must perform
Execute
The phase of the instruction cycle wherebthe task is carried out, which could be an arithmetic shift, logic or memory operation
Fetch-Execute Cycle
Also known as the instruction cycle, the complete process of retrieving an instruction from store, decoding it and carrying it out
Instruction
A single operation, one of these is executed each time the CPU performs the fetch-execute cycle
Main memory
Also known as RAM or Primary Storage, this is where data and instructions are stored in the Von Neumann architecture
Process
Computers take input, and produce output. This is what happens in between, which needs a CPU
Stored program
Von Neumann invented this concept, it means keeping the instructions in memory instead of inputting them each time through switches or paper tape
Central Processing Unit
This component repeatedly fetches, decodes and executes instructions. Often abbreviated to CPU
Architecture
The design of a computer, including the way its components are organised and the rules that male them work together. Von Neumann invented a type of this
Memory Address Register (MAR)
• Location address in memory of the next piece of data or instruction to be fetched or stored
Memory Data Register
A register that stores the data being sent to or retrieved from memory. This could be data to be processed, or an instruction being fetched.
Accumulator
A register in the ALU that holds data temporarily. It stores the results of calculations and logical operations.
Program Counter
• Continuously provides the CPU with the memory address of the next instruction in the cycle to be fetched.
Registers
The collection of tiny areas of extremely fast memory located in the CPU, each with a specific purpose, where data or control information is stored temporarily. Examples are the MAR, MDR, PC and Accumulator
Cache
A small amount of fast memory in the CPU. It stores the data and instructions most likely to be needed again and it is faster to access than RAM
Arithmetic Logic Unit (ALU)
• Where calculations are carried out
• These include: mathematical tasks, logic tests, data comparisons
Bus
Any of three communication pathways between the CPU and RAM in the Von Neumann architecture. There is one for addresses, one for data and one for control signals
Control Unit
Component of the CPU which controls the flow of data around the CPU, communication between the CPU and input and output devices, and decodes and executes instructions
