Max Memory Space Addressed by 18 Address Bits

[needhelp83]

The largest memory space that can be addressed by 18 addressing bits is...


Is there a formula for this perhaps?

 

[chroot]

How many different combinations of 18 ones and zeros are there?

- Warren

 

[needhelp83]

2^n
n=18

2^18= 262,144

 

[needhelp83]

Would that be 262,144 bytes then

 

[HallsofIvy]

Assuming that each "memory location" holds one byte, yes.

 

[needhelp83]

Thanks for the help?

 

[Mike Cookson]

Something to note - while you might be able to have addresses going all the way up to 2^18 a lot of chips do not have memory locations for all of the addresses. Such as variants in the PIC16F8X range.

 

[needhelp83]

I noticed in a Digital Circuits book that with 18 address leads it should be 256K. So where does my 262,144 come from with 2^18. Just a thought?

 

[chroot]

256 * 1,024 = 262,144. The "k" in this context means 1,024, not 1,000.

- Warren