# Memory Space

1. Mar 3, 2008

### needhelp83

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

Is there a formula for this perhaps?

2. Mar 3, 2008

### chroot

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

- Warren

3. Mar 3, 2008

### needhelp83

2^n
n=18

2^18= 262,144

4. Mar 4, 2008

### needhelp83

Would that be 262,144 bytes then

5. Mar 4, 2008

### HallsofIvy

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

6. Mar 4, 2008

### needhelp83

Thanks for the help?

7. Mar 4, 2008

### Mike Cookson

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

8. Mar 6, 2008

### 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?

9. Mar 6, 2008

### chroot

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

- Warren

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