Vacuum Tubes & Transistors
The Vacuum Tube Era
The birth of the digital computer
Jenya Pesin
Tal Sela
Edison’s light-bulb
Edison’s light-bulb
• Edison experiments with
incandescent lamps
• He notices an uneven
blackening of the glass
1880
The Edison effect
1880
The Diode
• John Ambrose Fleming
– first to put Edison’s ideas to
the test in a telegraph
communication detector
• Allows current flow in only
one direction
• Used to convert AC to DC
1880
1904
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DRL (Diode-Resistor Logic): OR
• If both inputs are held at
logic ‘0’, output is held at
logic ‘0’ by the ground
• Either input at logic ‘1’
will make its diode
forward biased and
conduction will pull output
up to logic ‘1’
The Triode
DRL (Diode-Resistor Logic): AND
• Only if both inputs are
held at logic ‘1’, neither of
the diodes conduct, and
the output is a logic ‘1’
• If either of the inputs are
logic ‘0’, its diode will
conduct and the resistor
will pull down the output
to a logic ‘0’
The Triode
• Lee de Forest invents the triode (“Audion”)
• Used as a current amplifier
• Many improvements based
on Fleming’s invention
followed, creating new kinds
of vacuum tubes
– The tetrode (two grids)
– The pentode (three grids)
1906
1906
Triode NOR gate
NOR: A complete system
• Example – an AND gate:
• DRL is not a complete
A system!
B
A nor B
logic
0
0
1
• Possible solution: DRL
0
1
0
and a triode NOT gate
1
0
0
• A better complete system:
1 gate 0
–1
a triode NOR
A
B
NOT A
NOT B
A AND B
0
0
1
1
0
0
1
1
0
0
1
0
0
1
0
1
1
0
0
1
2
ABC – Atanasoff-Berry Computer
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Built in Iowa state college
First electronic digital computing device
Solved problems with 29 linear equations
Not Turing complete
Total wire length: 1.6km
Weight 320kg
Vacuum tubes: 280
Not programmable
ABC – Atanasoff-Berry Computer
• Implemented three critical ideas, a part of
every modern computer:
• Binary digits represented data/numbers
• Calculations with electronics, not mechanics
• Separate computation and memory
• Controversy over “First computer”…
• Won lawsuit against ENIAC and declared first digital
computer
1942
Colossus: The motive
• During WW2, German “Lorenz” machines
were used to send encrypted messages.
• Colossus was built to
help decipher “Lorenz”
encoded messages.
• Emulated the “Lorenz”
machine.
1942
Colossus
• First to use shift registers
• First to introduce partial
programmability (by
rewiring)
• Was never powered
down unless
malfunctioned
• Was kept secret!
1944
ENIAC: The reasons
• Helped in the design of the Hydrogen bomb
• Ballistic calculations for large guns in WW2
• A time consuming operation:
– A person: ~20 hours
– Bush differential analyzer: ~15 minutes.
– ENIAC: ~30 seconds
1946
1944
ENIAC
Electronic Numerical Integrator and Computer
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Built in the University of Pennsylvania.
First large scale computing device.
Partially programmable by rewiring
17,468 Vacuum tubes, 7,200 diodes
Used decimal
representation
• Weight: 27 tons
1946
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EDVAC
Electronic Discrete Variable Automatic Computer
• Built in the University of Pennsylvania.
• Weight: 7.85 metric tons.
• Size: 45.5 square m.
1949
Von Neumann architecture
EDVAC
• First programmable
multipurpose computer
• More internal memory
than any preceding
computer (5.5KB in
mode
• Total memory: 5.5KB
(in modern terms)
• 6,000 Vacuum tubes,
12,000 diodes.
1949
The Manchester SSEM
• The early computers:
– Have fixed programs.
– Need rewiring in order to change the program
• In the Von Neumann computer
– Single storage structure to hold instructions and
data
– The instructions (program) are treated the same
way as data thus easily modified
Small-Scale
A working
Experimental
replica was
Machine,
built in 1998
“The Baby”
1948
The Manchester SSEM
1948
The Manchester SSEM simulator
• First Von Neumann architecture
computer
• SSEM determined the highest factor of
218 in 52 minutes…
• Input:
by setting sequences of
bits at chosen addresses
using a simple keyboard
1948
1948
4
EDSAC
EDSAC
Electronic Delay Storage Automatic Calculator
• Built at the university of Cambridge
• 3,000 vacuum tubes
The first program:
– Printed the squares of integers from 0 to 99…
First “video game”
(using ray tubes)
1949, May 6th: Machine in operation for first time.
• Was used to find the largest prime number
Printed table of squares (0-99), time for programme 2
of the time – 79 digits (!)
mins. 35 sec. Four tanks of battery 1 in operation
1949
1949
EDSAC accessories
EDSAC simulator
Input tape
Tape
splicer
Logbook
1949
UNIVAC - Universal Automatic Computer
• Developed by EMCC
(Eckert-Mauchly Computer
Corporation)
• First American commercial
computer
• Weight: 7.25 metric tons
• 5,000 vacuum tubes
• 46 Machines sold overall
1951
1949
UNIVAC
• Used to predict US 1952 elections
• First to use magnetic tape output
• 1000 calculations per second.
1951
5
IBM 701
IBM 701
Drum memory
• IBM’s first commercial scientific computer
• Built to help the US government in the
Korean war
• 16,000 addition/subtraction or 2,000
division/multiplication operations per second
• Various IO mechanisms:
– Input: Punched cards, magnetic tapes
– Output: Punched cards, printer
The 11-part IBM-701
Card reader
1953
WEIZAC - Weizmann Automatic Computer
• First Computer in Israel
• Punch paper tape
• 5 KB total memory
1953
WEIZAC
The console of the
WEIZAC
The WEIZAC Console
The WEIZAC CPU
1954
1954
P-N Junction
The Transistor Era
• Russell Ohl studying crystals in the Bell
Labs
1939
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The transistor
P-N Junction
• Work on the P-N junction continued
• First transistor invented at Bell Labs by
Bardeen and Brattain
No current measured
Current measured
1939
The transistor
1947
The transistor
1947
The transistor
1947
The transistor
0V
5V
1V
5V
1947
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The transistor
Why not point contact transistor
The first point contact transistor
1947
1947
The transistor
The transistor
• William Shockley invents the sandwich
transistor
• Easy to manufacture
• More reliable
First sandwich transistor
1947
1947
Using the transistor
Building a NOT gate using RTL
(transistors and resistors)
Using the transistor
Building a NAND gate using RTL
C
C
E
E
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Early transistors
More modern transistors
1947
Transistor – the reasons
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More reliable
Less space
Cheaper
Less power
1947
IBM 608
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First completely transistorized computer
50% reduction in size
90% reduction in power requirements
Cost: 83,210$
1955
IBM 7090
• General purpose transistor logic computer
• Computing speed 5 times faster than the
vacuum tubes computers
Bibliography
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http://www.play-hookey.com/digital/electronics/dl_gates.html
http://en.wikipedia.org/wiki/Thermionic_emission
http://www.allaboutcircuits.com/vol_3/chpt_13/2.html
http://www.jacmusic.com/html/articles/ericbarbour/howavacuumt
ubeworks.html
http://www.4p8.com/eric.brasseur/intvac.html
http://en.wikipedia.org/wiki/Diode_logic
http://www.quadibloc.com/comp/cp01.htm
http://en.wikipedia.org/wiki/Atanasoff-Berry_Computer
http://cs.ubc.ca/~hilpert/e/ABC/asm.html
http://en.wikipedia.org/wiki/Colossus_computer
http://en.wikipedia.org/wiki/ENIAC
http://en.wikipedia.org/wiki/EDVAC
1958
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Bibliography
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http://www.ece.umd.edu/~taylor/Electrons3.htm
http://www.comsci.us/history/gen1.html
http://www.computerhistory.org/timeline/?category=cmptr
http://www.thocp.net/hardware/univac.htm
http://wwwcsif.cs.ucdavis.edu/~csclub/museum/items/univac.ht
ml
http://www.cc.gatech.edu/gvu/people/randy.carpenter/folklore/v
5n1.html
http://www.davidsharp.com/baby/babyuserguide.pdf
http://www.cl.cam.ac.uk/conference/EDSAC99/reminiscences/
http://edsac.net/
Bibliography
• http://www.cl.cam.ac.uk/cgibin/relicd?name=&machine=EDSACI&class=any&uid=
• http://www.wisdom.weizmann.ac.il/weizac/weizac.html
• http://www03.ibm.com/ibm/history/exhibits/vintage/vintage_4506VV2214.ht
ml
• http://www.columbia.edu/acis/history/generations.html
• http://www03.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP7090.
html
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