RAM Model

A sequential algorithm is formulated using an abstract model of computer called RAM (random access model), where a single processor is connected with a random access memory system. All the arithmetic and logical operations require one time step.

The random access machine (RAM) models a one-accumulator computer in which instructions are not permitted to modify themselves. The input tape is sequence of squares, and holds an integer each. Write instruction prints an integer in each square $y_i$. The memory consist of locations $r_0, r_1, \dots$, each of which can hold an integer of arbitrary size. The instruction set of RAM machine is: add, sub, mul, div, load, store, read, write, j, jnz, jz, hlt. In general, a RAM program defines a mapping from input tape to output tape.

Figure: RAM model.