Revision computer

Revision computer

1. I can describe what is meant by cores and explain how it affects performance.

   • The number of independent processors in the CPU which run the fetch decode execute cycle simultaneously.Dual core: 2 independent processors in the CPU working simultaneously.Quad core: 4 independent processors in the CPU working simultaneously. Simultaneously: At the same time.

2. I can describe what is meant by cache and explain how it affects performance.

   • Cache is a small amount of memory which is a part of the CPU - closer to the CPU than RAM. It is used to temporarily hold instructions and data that the CPU is likely to reuse. The CPU control unit automatically checks cache for instructions before requesting data from RAM. This saves fetching the instructions and data repeatedly from RAM – a relatively slow process which might otherwise keep the CPU waiting. Transfers to and from cache take less time than transfers to and from RAM.The more cache there is, the more data can be stored closer to the CPU.

3. I can describe the differences between RAM and ROM

   • The terms "RAM" and "ROM" refer to two types of computer data storage. RAM is an acronym for "random access memory," while ROM stands for "read-only memory." RAM and ROM are alike in certain respects as two forms of memory, so they are easily confused. read-only memory The terms "RAM" and "ROM" refer to two types of computer data storage. RAM is an acronym for "random access memory," while ROM stands for "read-only memory." RAM and ROM are alike in certain respects as two forms of memory, so they are easily confused.

4. I can explain why a computer system needs to have ROM

   • ROM retains its memory even after the computer is turned off. For example, ROM stores the instructions for the computer to start up when it is turned on again.

5. I can describe the difference between a variable and a constant

   • During the running of a computer program, there will be times when the program needs to remember/store a value so it can be read and used later on.In order to store a value, the program needs to establish a memorable (named) place (data structure) that it can use to hold the data. These locations are called variables and constants.A program can contain many variables and constants, so it is important to give them sensible names that try to describe the item of data that they hold.The key difference between a variable and a constant is: The value stored in a variable can/may change during the running of the program The value stored in a constant cannot be changed during the running of the program Both constants and variables can only hold one piece of data at a time. When a new value is assigned to variable (using an assignment statement) it automatically replaces whatever was stored previously.

6. I can describe what is meant by sequence, selection and iteration.

   • Sequence- A set of instructions in an order. Selection-Instructions which which will run depending on a condition being true or false. Iteration-Instructions which can repeat (either a set number of times or depending on a condition being true or false).