So here's a little program that shows that going on.

We start off with an integer.

We'll call this bigData.

Some integer, 16 bits that we're interested in, okay.

And we wanna write this into the EEPROM into an address.

Then you got a byte we'll call littleData.

What we're going to do is make littleData one byte of bigData.

So we're gonna take big data and first write one byte of it as little data and

then another byte.

So in the set up we say little data equals big data and oxff.

So what does that mean?

That is performing the bid wise and with the mask so oxff is my mask.

Now that notation is called hexidecimal notation right.

A hexidecimal notation, we didn't go over it but hexadecimal is base 16.

And at base 16 you have 16 digits.

Zero through nine plus a, b, c, d, e, and f.

Okay, so, a is ten, B is 11, so on, and F is a 15.

So notice that is OX, OX means hexidecimal, and

the actual value in hexidecimal is FF, and F is a 15, which in binary is all ones,

is one, one, one, one, F is just one, one, one, one.

So if I say FF that is one, one, one, one, one, one, one, one.

That is eight ones in a row.

That is exactly the same as the mask that we used before.

All zeros, and then eight ones.

So 0xFF is the same as the mask that we used on the last two slides.

So this is just a shorthand.

Now people, you should be used to this shorthand a little bit,

because this hexadecimal shorthand is commonly used.

It just makes numbers shorter, right?

Rather than drawing 16 bits, I can just draw these Fs.

0xFF is much shorter.

So it's a common shorthand you'd be using when you're programming IoT devices.