Stored Program Computers and Computer Memories: Part 1

Question 1

Before stored program computers

Answer 1

Machines received instructions from tape or punched cards; Hard wired connections

Question 2

John Von Neumann (1903 - 1957)

Answer 2

A renowned genius;
Credited with the invention of SPC’s

Question 3

Von Neumann and the EDVAC

Answer 3

Participated in discussions on the design(instructions stored on tape); Wrote the first report on the EDVAC

Question 4

Thermal memory

Answer 4

Used temperature changes to store and retrieve information. It was unreliable

Question 5

Mechanical memory

Answer 5

Z1 sliding plates, relays, disk-pin. However, it was much slower than electronics

Question 6

Mercury delay line

Answer 6

Binary number represented using pulses; Difficult to get good contact b/w mercury and quartz

Question 7

Acoustic delay line

Answer 7

Inexpensive, theoretically possible; Prone to interference

Question 8

Slinky delay line

Answer 8

Current passes through the slinky; Slinky would oscillate too much

Question 9

Magnetostrictive delay line

Answer 9

Wave would go through the wire towards a magnet that would amplify the pulse. Less temperature sensitive than Mercury delay line

Question 10

Delay Line Drawbacks

Answer 10

Delay;
Information stored in the delay mechanism was only available after a delay

Question 11

Electrostatic memory

Answer 11

First high speed random access memory (Form of vacuum storage)

Question 12

Read around problem

Answer 12

Leaving a bit on for too long would corrupt its surrounding bits

Question 13

Selectron

Answer 13

Wafers consisting of states opened by currents; Costly

Question 14

Rotating magnetic memories

Answer 14

Impractical for real use (slow access time)

Question 15

Two level memory

Answer 15

Magnetic drum(slow, high capacity) and Williams tube(fast, low capacity)

Question 16

Booth’s magnetic memory disk

Answer 16

Developed floppy disk based memory, and then magnetic drum memory which was used in the ABC

Question 17

Static Magnetic Core Memories

Answer 17

Detection wire to detect if both horizontal and vertical wire were magnetized

Question 18

Core Memory significance

Answer 18

Speed increased by a multiple;
Maintenance time drastically decreased

Question 19

Core Memory advantages

Answer 19

cores can be small;
non-volatile;
Random access