Systems architecture (1.1) GapFill

In a computer system, components are arranged so that the CPU is connected to input and output devices as well as to data storage an external clock an embedded system a program counter . The CPU is responsible for processing all of the operations that need to be carried out by the computer and is composed of the data bus control bus ALU (Arithmetic Logic Unit) RAM , the CU (Control Unit), registers and cache read-only secondary virtual memory.

The CPU runs in a fetch-execute cycle to retrieve one instruction, carry out that instruction, retrieve the next instruction and so on. The CPU uses registers clocks ALU heatsinks to store the data that is used in this process. The fetch-execute cycle is carried out as follows:

• The memory address of the next instruction to be executed is copied from the ALU PC MDR CU to the MAR
• This value is copied to the MDR increased by 1 copied to the MAR doubled while the data stored in the memory location pointed to by the MAR is copied into the MDR
• The instruction is copied from the CU ALU MDR PC to the CIR
• The instruction is then decoded by the accumulator ALU cache memory CU
• The instruction is executed

Factors which affect the performance of the CPU include the number of users buses input/output devices cores , the CPU's cache clock accumulator memory speed and the amount of available secondary storage cache memory RAM ROM .

Sometimes a computer may not act as a standalone device, but instead be built into a larger device to perform some specific task. This sort of computer is known as an open-source system an embedded system an iterative system a nested system .