Addressing Modes

Memory Addressing Modes of 8086

Most of the memory ICs are byte oriented i.e. each memory location can store only one byte of data. The 8086 is a 16-bit microprocessor, it can transfer 16-bit data. So in addition to byte, word (16-bit) has to be stored in the memory. This is stored by using two consecutive memory locations, one for least significant byte and other for most significant byte. The Memory Addressing Modes of 8086 of word is the address of least significant byte. To implement this, the entire memory is divided into two memory banks : bank0 and bank1. Fig. 10.11 shows the interfacing diagram to these memory banks. Bank0 is selected only when A0 is zero and Bank1 is selected only when BHE is zero. A0 is zero for all even addresses. So Bank0 is usually referred as even addressed memory bank. BHE is used to access higher order memory bank, referred to as odd addressed memory bank.