maximum memory address space

[ednan]

Plz my question as soon as possible...

Wat is the maximum memory address space that the prosessor can access directly if it is connected to a 16 bit memory?

 

[Johansen]

65336 bytes

 

[echo47]

When you say "16 bit memory", do you mean 16 data bits or 16 address bits?

If 16 address bits, then it can address 65536 words, but the word size is unknown.

If 16 data bits, then there's insufficient info to answer the question.

 

[laktronics]

Hi,
As Mr.echo47 has told, the '16 bit' in 16 bit memory normally refers to the data width of the memory, it could even be a serial memory for external access. A CPU's direct memory addressing range does not depend upon the data width or the address range of the memory to which it is connected, it only depends upon the memory adressing range of the CPU.

Regards,
Laktronics

 

[ednan]

Yes we have 16 bit address and data bus .....

and if we have 16 bit address and data bus and then maximum address space that processor can directly access if it s connected to 8 bit memory is 256...is it right

 

[laktronics]

Hi,
No, it is exactly what I was trying to tell you in my post. CPU's direct addressing capability depends only on its address bus width and not on the the capacity of the memory unit to which it is connected. For a CPU with 16 address lines as in 8051, you can directly address up to 2^16 locations (64k) and it does not get reduced just because you have presently connected it to a 1K memory. It is a specification of CPU.
Regards,
Laktronics

 

[ednan]

Plz tell me the answer of my question....

 

[echo47]

A processor with 16-bit address bus and 16-bit data bus probably has an address space of 65536 16-bit words, however check its data sheet to be sure. Some processors do tricky things such as providing 16 address bits when accessing 8-bit data, and 15 address bits when accessing 16-bit data.

The term "processor address space" is the amount of memory the processor is capable of accessing, not necessarily the amount of memory you've connected to it. If you wish to talk about the size of a particular memory attached to a processor, then I suggest avoiding the term "address space".

You mentioned "8-bit memory" without clarifying if you meant 8-bit data or 8-bit address.

 

[ednan]

yes i mentioned that if we have
"16 bit address and data bus and then wat maximum address space that processor can directly access if it s connected to 8 bit memory"

 

[FvM]

The question is still ambigous, unfortunately. 16 bit address bus has 2^16 addresses, but this may be byte or word addresses. I don't know any real processor with 16 bit data, that has only 16 address bit, but it could exist.

If it also would use byte addressing as a x86 processor, then it could access 2^16 = 65536 bytes respectively has a 64k memory space.