Week 3 Notes!

Question 1

Battery

Answer 1

Positive and negative terminals

Question 2

Switch

Answer 2

Closed vs open circuit

Question 3

Morse Code

Answer 3

Used sound because people are more sensitive to sound that light

Can be described as binary

Hard to remember

Question 4

Original Telephone

Answer 4

Mousepiece
Cup of acid
Metal rod

Varies current in an analog manner

Question 5

Date of telephone

Answer 5

March 10, 1876

Question 6

First words

Answer 6

Mr. Watson, come here, I want to see you

Question 7

Design

Answer 7

Wire gets electricity from a batter and gives it to the acid. In the original design, it was dipped down into the acid, but it can also connect to the metal in any way.

Another wire is attached to the membrane. It moves in and out of the liquid, thereby changing the strength of the electromagnet at the receiving instrument and causing the armature to vibrate.

A weak acid like vinegar also works.

Acid was unsafe

Question 8

Edison Telephone

Answer 8

Used carbon instead of acid, safer.

Still had the problem of using a mouthpiece.

Had the problem of needing individual copper wires.

Question 9

Individual Copper Wires Solution

Answer 9

Used a rotary dials.
Used human operators.

Question 10

Western Union

Answer 10

First to span the US with pony express
Later switched to telegraphs which had error from human operators relaying messages every ten miles.

Question 11

Bell Telegraph Company Founding

Answer 11

1890

Question 12

Human Operators Solution

Answer 12

Large, centralized switches connected by trunk lines

Question 13

Analog vs Digital Telephones history

Answer 13

As telephones are amplified, noise amplitude approaches signal amplitude.

DAC- Digital Analog Conversion
ADC- Analog Digital Conversion
With full conversion, only loss is ADC

Digital telephones were released, but costed $3,000

Later, digitization was used only for internal messages

Question 14

Private Branch Exchange

Answer 14

Prevents cost of subscribing to many phone lines

Question 15

Punchcards

Answer 15

Batch processing meant that turn around times were very long eg 2 weeks.

Metal rods could touch through the paper.

Bad due to mechanics

Question 16

IBM Selectric

Answer 16

Used the golf ball method to send data to a mainframe

Bad due to mechanics

Question 17

Integrated Circuits

Answer 17

From keyboard, to integrated computer, to mainframe

Early terminals needed to be close to terminal as they were connected by a wire.

Question 18

Morse Code

Answer 18

5 bits

Question 19

Bandot ASCII

Answer 19

7 bits

Question 20

EBCDIC

Answer 20

8 bits, an IBM specific character encoding that existed as an accident of history

Question 21

Mouthpiece solution

Answer 21

The Carterphone

You could communicate by sending data from your speaker to the cartphone’s microphone

Getting data with your mic from the carterphone’s speaker

Similar designed later used in early computer networking