Random Access Machine model

Algorithms can be measured in a machine-independent way using the Random Access Machine (RAM) model. This model assumes a single processor. In the RAM model, instructions are executed one after the other, with no concurrent operations. This model of computation is an abstraction that allows us to compare algorithms on the basis of performance. The assumptions made in the RAM model to accomplish this are:

• Each simple operation takes 1 time step.
• Loops and subroutines are not simple operations.
• Each memory access takes one time step, and there is no shortage of memory.

For any given problem the running time of an algorithms is assumed to be the number of time steps. The space used by an algorithm is assumed to be the number of RAM memory cells.