Memory of 64×8 bits means ________________.
Memory of 64×8 bits means It memory space is 64 byte.
A 32bit machine the maximum amount of memory usable is around 4GB. Actually, depending on the OS it might be less due to parts of the address space being reserved: On Windows you can only use 3.5GB.
Example. On 64 bit you can indeed address 2^64 bytes of memory.
64-bit computing is the use of processors that have data path widths, integer size, and memory address widths of 64 bits.