EXAMPLES OF MEMORY INTERFACING (Contd..)
EXAMPLE-4
Consider a system in which the 64kb memory space is implemented using eight numbers of 8kb memory. Interface the EPROM and RAM with 8085 processor.
- The total memory capacity is 64Kb. So, let 3 numbers of 8Kb EPROM and 5 numbers of 8Kb RAM.
- Each 8kb memory requires 13 address lines. So the address line A0 - A12 of the processor are connected to 13address pins of all the memory lCs.
- The address lines A13, A14 and A]5 are decoded using a 3-to-8 coder to generate eight chip select signals. These eight chip select signals can be used to select one of the eight memories at any one time.
- The memory interfacing is shown in following figure.
Fig - Interfacing 4 no. 8Kb EPROM and 4 no. 8Kb RAM with 8085
