Question

The 68HC11 can address 512K bits of information. Your company is considering developing the next generation micro the 68HC11 which will use 1024K bits. What changes to the address and/or data lines are required to make this change?

Answer 1

68HC11 is a  16 bit address and 8 bit data bus processor.

16 bit address bus will have address space of 2¹⁶ = 65536 location

Each location have 8 bit data storage will give 65536 x 8 = 524288 bits (512K bits)

To store 1024 K bits , let assume data bus of 8 bits.

Hence total address locations = 1024Kbits / 8 bits = 128000 locations

log₂ 128000 = 17 bit address bus

Hence address bus needed is 17 bits and 8 bit data bus.