what exactly is software?It is the combination of Instructions and Data, known as machine code that forms the building blocks of applications such as Word Processor, Computer Game or Spreadsheet.
This machine code lives in the memory of the computer as billions of little on off switches. Exactly the same as a number in a calculator.
The CPU is the Brain
The heart of the computer is the CPU plus its RAM. The CPU fetches data from RAM, carries out operations on the data and then stores it back in RAM. The CPU can also fetch data from permanent storage such as ROM, floppy disk, Flash or hard disk. It's permanent because when the power is switched off, a copy remains there.How Big is a Program?
Computer programs can be as small as a few hundred bytes or as large as a few billion bytes. When a program is loaded into RAM from disk, the pattern of the bits is copied exactly- even one bit wrong can cause the program to fail. Computer hardware has been engineered so this doesn't happen.If an application is 40 Megabytes in size, then roughly 320 Million bits are copied into RAM.
The prefix Kilo, Mega and Giga indicate the size of a program or data file in bytes. A Kilobyte is 1024 bytes, a Megabyte is 1024 Kilobytes and a Gigabyte is 1024 Megabytes. Put another way, a Gigabyte is 8,589,934,592 individual on/off switches!
