The address area is the possible memory area of ​​an integrated circuit (IC) that can be addressed .

## Address area in RAM chips

Addressing is possible with the address bus , which consists of a certain number of pins (connections). These can be set either to "High" or "Low" (specified voltage values , the '1' or '0' group; for example, in TTL - ICs 5 V and 0 V). Therefore, there are two possibilities for each pin. This results in n possibilities for n pins 2 .

This can be illustrated more precisely using an example: The RAM chip 51256 is a 32Ki * 8bit static RAM . 32Ki means that 32,768 different addresses are possible. The chip has a memory location of 8 bits for each address. (The memory locations of other chips sometimes have different sizes, e.g. only 4 bits / memory cell, or each memory cell is 32 bits.) From the number of possible addresses, the above formula (2 n ) can be used to calculate a number of pins of 15 close. This results in an address range for 15 pins from 0 to 32,767 or in dual notation: from 000.0000.0000.0000 to 111.1111.1111.1111.

## Address area in the microcontroller

For example, a 8051 - microcontroller has an internal 64k data memory; 16 pins are required there (but these are only accessible internally); its data memory therefore has an address range from 0 to 65535. The internal program memory has an address range from 0000H to 0FFFH (see: hexadecimal system ); these are 12 bits or pins for addressing in its program memory.