Relation between Number of Address Pins and Memory Capacity

Memory Capacity:

A semiconductor memory IC will have n address pins and m data pins. Such a memory has 2n locations and each location can store m-bit data. The size of data stored in each memory location is called memory word size. In INTEL 8085-based systems normally memories with a word size of 1 byte are used. (But we can even interface memories with word sizes 1-bit, 2-bit, and 4-bit.)

The memory capacity is specified in kilo bytes. If the memory IC has m data pins and n address pins, then the memory IC will have a capacity of 2n × m bits. When m = 8, the memory capacity is 2n bytes. One kilo-byte is 102410 (= 400H) bytes. The relation between address pins and capacity of memory ICs are listed in Table