• So you don’t look stupid when you get to your job.
• To prepare you for hands-on courses like
CS 150 that involve hardware design.
• Because it’s good to know the physical basis of computation.

All information inside a computer is represented numerically.
 Text: Every letter is represented by a number
(ASCII code).
 Images: A bitmap image is a table of numbers, with each entry representing the color of a pixel.
{
= 123
Row 3, Column 2 = 00FF44

There are many ways to represent numbers.
 Decimal (base 10, the usual way)
 Hexadecimal (base 16, often used in the study of computers)
 Binary (base 2)
The ability to represent any number in binary, using 0’s and 1’s, makes computation as we know it possible.

The numbers 0 and 1 are represented by physical quantities:
 The number 0 (called logic 0) is represented with a voltage near 0 V.
 The number 1 (called logic 1) is represented with a voltage between 2 and
5 V, depending on the technology.
Circuits perform computation by taking voltage inputs and allowing current to flow, creating voltage outputs.

B
A
The mathematical operation known as
“AND” is performed by this circuit:
V
DD
S S S
V
DD
D
D
S
A B
S
S

To analyze the circuits that perform computation, you need to know about
 Circuit analysis : voltages and currents so you can see how circuits work, resistance and capacitance so you see how long it takes to compute something
 Electronics : transistors which make complex computation feasible

We will look inside
 Memories: DRAM, latches, flipflops…
 A/D and D/A Converters
 Logic Gates and more!