Studied by 1 personVirtual memory
A process when the OS moves a page/segment from RAM into virtual memory when its likely not to be needed.
Virtual RAM
If RAM is full OS creates more using secondary storage
RAM (Random access memory)
Temporary memory that stores programs that are loaded. Limited so more RAM can increase performance.
ROM (Read only memory)
Fast permanent storage. Stores the BIOS. Cannot be overwritten. Non volatile so power is not required to access ROM.
Cocurrency
Multiple instructions can happen at the same time.
Disadvantages of parallel processing
Only certain types of data are suitable for parallel processing.
Advantages of parallel processing
More than one instruction is processed at one time making processing faster.
Examples of MIMD
Used in supercomupters
MIMD (Multiple instruction multiple data)
Multiple instructions are carried out on multiple data. Used in multi core processing.
Example of SIMD
Mathematical problems such as weather forecasting
SIMD (Single instruction multiple data)
A single instruction is carried out on multiple pieces of data at one time. This is used in array processor.
Parallel processing
Approach when a computer carries out multiple computations simultaneously to solve a given problem.
Disadvantages of RISC
More RAM space is required and compiler software has to work harder
Advantages of RISC
Faster due to simple instructions and is also cheaper to make
Use of RISC
Used on many portable devices
RISC (Reduced instruction set computer)
Contains fewer and simple instruction sets. Has a simple architecture
Compiler
Looks at commands and translates to binary
Disadvantages of CISC
Programs can run slower due to complex instructions
Advantages of CISC
Complex instructions and lots of addressing modes
Use of CISC
Used to make compiler development easier
CISC (Complex instruction set computer)
Complex and larger set of instructions. Has a single register set
Harvard Architecture
Has physically seperate memories for instructions and data. Has seperate data buses.
Pipelining Flush
A proccess enacted by CPU when it cannot ensure it will correctly proccess its instruction in the next clock cycle
Disadvantage of Pipelining
Only possible if the program counter knows the next instruction to be fetched
Advantage of Pipelining
Improves performance
Pipelining
Is a process of completing FDE cycles of three separate instructions simultaneously
Polling
when the OS will constantly check if any peripherals needs it's attention
Control bus
Sends control signals from the control unit to other parts of the processor. It synchronises commands of the processor.
Data bus
Carries data being transmitted between areas of the processor.
Address bus
Carries address to which the instruction/data is being transmitted.
Bus
A set of parallel wires connecting two or more components of a computer. They consist of 8,16,32 or 64 lines.
Current Instruction Register (CIR)
Holds the current instruction that is being executed.
Memory Data Register (MDR)
Temporarily stores data that has been read or data that needs to be written.
Memory Address Register (MAR)
Holds the address in memory of the data to be fetched and stored. Specifies the location where data is read from or written to.
Accumulator register (ACC)
Temporarily stores data during processing and is involved in calculations.
Program counter register (PC)
Indicates the address of the next instruction to be executed.
Register
Special memory cells that operate at very high speeds. They are memory stores inside the CPU that store data.
Arithmetic Logic Unit (ALU)
Completes all of the arithmetic and logic operations. It performs mathematical operations
Controll Unit
Manages and coordinates all of the CPU activity. It directs flow of data between the CPU and other devices. It manages execution of instructions
System clock speed
Generates a series of signals which regulates the operations of the CPU when its performing the FDE cycle
Note
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