Computer architecture (The Von Neumann machine) and the CPU

Decode

The second step is for the CPU to make sense of the instruction it has just fetched.

Control Unit (CU)

1. It controls and monitors the hardware attached to the system to make sure that the commands given to it by the application software are used. 2. It controls the input and output of data so that the signals go to the right place at the right time. 3. It controls the flow of data whitin the CPU.

The Von Neumann or Stored Program architecture

A design architecture for an electronic digital computer with parts consisting of a processing unit containing an arithmetic logic unit and processor registers, a control unit containing an instruction register and program counter, a memory to store both data and instructions, external mass storage, and input and output mechanisms.

Overclocking

Adjust the clock to run faster than the CPU was really designed for.

Memory

Can hold both data and also the program processing that data. In modern computers this memory is RAM.

Execute

The third step when data processing actually takes place.

Input-Output

Controllers that are used by the CPU to communicate with peripherals e.g. mouse and keyboard.

Computer architecture

Describes how a computer is conceptually put together.

CPU Cache

Is a cache used by the central processing unit of a computer to reduce the average time to access data from the main memory.

Bus

Is a communication system that transfers data between components inside a computer, or between computers.

Control Unit

Is a component of a computer's central processing unit (CPU) that directs operation of the processor. It tells the computer's memory, arithmetic/logic unit and input and output devices how to respond to a program's instructions. This includes the idea of a "register" to hold intermediate values.

Program Status Word (PSW)

Is a control register which performs the function of a Status register and Program counter in other architectures, and more.

Arithmetic Logic Unit

Is a digital circuit that performs arithmetic and bitwise logical operations on integer binary numbers.

Registers

Is a discrete memory location within the CPU designed to hold temporary data and instructions.

CPU

It is the "brain of the computer, where all the searching, sorting, calculating, and decision making takes place in the computer.

Fetch-decode-execute cycle

Standard process describes the steps needed for processing to take place.

"One-at-a-time"

The Von Neumann architecture is a sequential processing machine. Computers can only do one thing at a time.

"Von Neumann bottleneck"

The data bus is a lot slower than the rate at which the CPU can carry out instructions.

Fetch

The first step the CPU carries out is to fetch some data and instructions (program) from main memory than store them in its own internal temporary memory areas.

Program Counter (PC)

This holds the address in memory of the next instruction.

Current Instruction Register (CIR)

This holds the current instructions to be executed, having been fetched from memory.

Immediate Access Store

This holds the data and programs needed at the instant by the CU.

Memory Address Register (MAR)

This holds the location in memory (address) of the next piece of data or program to be fetched (or stored).

The Harvard Architecture

This idea is to split the memory into two parts: one part for data and another part for programs. Each part is accessed with a different bus and this means the CPU can be fetching both data and instructions at the same time (there is also a less chance of program corruption).

Number of cores

Using two CPUs at the same time you can improve the speed of a computer.

Memory Buffer Register or Memory Data Register

When the data or program instruction is fetched from memory, it is temporarily held in the MBR.