[8 points for showing up]

You have up to 25 minutes. You may use a calculator, but no text book or notes.

**Use the hexadecimal codes in the right column to fill in the 8×8 icon grid, assuming 1 bit per pixel.**[8 points]Note that I probably intended

`36`

on the last row… it looks like there’s a piece missing. This is indeed from Space Invaders.**If an image uses 6 bits per pixel, what is the maximum number of colors it can contain?**[8 points]With 6 bits per pixel, we can have 2⁶ colors, and 2⁶ = 64.

**Suppose you work for a CPU manufacturer that has exhausted its supply of XOR gates. Show whether or not the expression is equivalent to by completing a truth table of all possible values of inputs and .**[8 points]They are the same. Below is the truth table that proves it. You do not need to write the circuit diagram shown above the table – that’s just a convenient way to show how each column is calculated.

Recall that XOR is a way to say “not equal to.” Its result is true when A and B are

*different.***In the memory hierarchy, what is the main difference between**[8 points]*volatile*and*persistent*memory?Some of you just stated the main organizing principle of the memory hierarchy: faster, smaller capacity vs. slower, larger capacity. That may be true, but the

**main**difference is what happens when the power is cut.Volatile memory loses its content, while persistent memory retains it.