Internal address latch in 8085 Microprocessor


The select unit of the register in the 8085 selects any one of the register pairs (BC, DE, HL, SP, PC, or WZ) for sending them to it to the latch unit specified for addressing. For example, the contents of the PC be C200H. If the selection unit be the register which selects the PC, and sends C200H from the PC to the address latch internally thereafter the latch holds the specified value and sends directly out to the pins of the address after buffering. The Most Significant Byte of the address i.e. the C2H, is sent out to the addresses ranging from A15 to A8, and the Least Significant Byte of the address turns to 00H, is sent out to the pins ranging from AD7 to AD0 respectively.

After that, the PC value gets incremented, but the latch continues to have the values C200H. This value of C200H is sent out to the pins of address of 8085 even though the content of the PC gets already incremented.

Published on 11-Mar-2019 11:15:52