The amplitude is the power of a signal. The greater the amplitude, the greater the energy carried.

Rather humble beginnings, yet the Apple I led to the very successful Apple II series, which thrived for many years. (Image courtesy of Apple Computer

asynchronous transmission

The transmission of data in which each character is a self-contained unit with its own start and stop bits. Intervals between characters may be uneven. It is the common method of transmission between a computer and a modem, although the modem may switch to synchronous transmission to communicate with the other modem. Also called "start/stop transmission." Contrast with synchronous transmission.

The fastest PC in 1984. Users were amazed at the extraordinary speed of the 286 with its huge 20MB hard disk.

A hundred years ago, the concept of the future lacked one major ingredient... the computer! (Image courtesy of Rosemont Engineering.)

Alexander Graham Bell

Alexander Graham Bell was born in Scotland in 1847 and died in 1922. His famous sentence "Mr. Watson. Come here! I want you!" were the first words to travel over a wire, ringing in the birth of electronic communications. (Image courtesy of AT&T.)

AND

AND requires both inputs to be present in order to provide output. Because the AND gate is wired in series, both inputs must pulse both switches

Curious About the Chip?

Wired in patterns of Boolean logic and in less space than a postage stamp, transistors inside one of today's high-speed chips collectively open and close trillions of times every second. If you're curious about how it really works down deep in the layers of the silicon, read the rest of "Boolean logic," then "chip" and, finally, "transistor." It's a fascinating venture into a microscopic world.

The logic of AND, OR and NOT is implemented as transistors, which are electronic switches that are opened and closed by being pulsed.

OR

OR requires one input to be present in order to provide output. Because the OR gate is wired in parallel, either one or both inputs will generate

NOT

NOT reverses the input. If there is no pulse on the input line, the source goes directly to output, as in the diagram above. If there is a pulse on the input line, switch #1 is closed. The switch #1 current goes to switch #2 and pulses it open (it's a reverse switch), and the source current is impeded.

Could They Have Imagined?

As Europeans began to use their new-fangled Ericsson phones in the late 1800s, could they have imagined the wireless world of cellphones 100 years later? Picture taken at Antoni Gaudi's famous "La Pedrera" apartment house in Barcelona.

Definition of a Chip

A set of microminiaturized, electronic circuits that are designed for use as processors and memory in computers and countless consumer and industrial products. Chips are the driving force in this industry. Small chips can hold from a handful to tens of thousands of transistors. They look like tiny chips of aluminum, no more than 1/16" square by 1/30" thick, which is where the term "chip" came from. Large chips, which can be more than a half inch square, hold millions of transistors. It is actually only the top one thousandth of an inch of a chip's surface that holds the circuits. The rest of it is just a base. The terms chip, integrated circuit and microchip are synonymous.

How the Chip came about.