# Help me understand address space?

1. Jul 27, 2016

### fireflies

Address space is the total number of identifiable locations in memory. I just learnt that line. What does that mean elaborately?

like it is said, a memory with 64KB and a word size of 1 byte has an address space ranging from 0 to 65535. How that came from? And why ranging? because I got two other examples saying exact adresses?

the examples are:
1) A computer has 32 MB memory. How many bits are needed to address any single byte in memory?
Solution: 25 bits
2) A computer has 128 MB memory. Each word (what is the word elaborately?) is 8 byte. how many bits are needed to address single word? (Can you please make me understand tge question and the calculation?)
Solution: 24 bits

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2. Jul 27, 2016

### BvU

A binary number with $n$ bits can take on $2^n$ different values.

In IT, the prefix K means $2^{10}$, which is 1024 in decimal notation. So 64 KB = 65536. That is also $2^{16}$. Older computers had 16 bits for addresses, in that way they could form 65536 different addresses.

The examples are exercises for you, not for PF. So you first should make your own attempt and post . Don't worry, help will surely come your way.

3. Jul 27, 2016

### fireflies

IThanks for helping..

I just don't understand this part of the examples-

How many bits are needed to address any single word in the memory.. and the solution done with log base 2

4. Jul 27, 2016

### fireflies

I think I got the point :) Thanks you