1. Vacuum tubes were used as switches in early computers but had issues like generating a lot of heat and being unreliable. They were replaced by transistors. 2. Integrated circuits were invented in the late 1950s and represented the next generation of computers. They placed multiple circuit components like transistors onto a single semiconductor substrate. 3. Integrated circuits are superior to vacuum tubes because they use transistors which are smaller, more reliable, and can contain many more components than vacuum tubes.

1. Assignment
SUBMITTED BY:
LARAIB KIRAN
SUBMITTED TO:
PROF. KHIZAR ABBASS
ROLL NO.:
H1F18MSCT0020
SUBJECT:
DIGITAL LOGIC DESIGN
Topic:
VACCUM TUBES vs INTEGRATEDCIRCUITS
CLASS:
M.sc (IT)

2. Vacuum Tubes:
Any modern digital computer is largely a collection of electronic switches.
These switches are used to represent and controlthe routing of data elements
called binary digits (or bits). Becauseof the on-or-off natureof the binary
information and signal routing the computer uses, an efficient electronic switch
was required. The firstelectronic computers used vacuumtubes as switches, and
although the tubes worked, they had many problems.
The three maincomponents of a basic triode vacuum tube:
1. Grid
2. Plate
3. Heated Cathode
The type of tube used in early computers was called a
triode and was invented by Lee De Forestin 1906. It
consists of a cathode and a plate, separated by a
control grid, suspended in a glass vacuumtube. The
cathode is heated by a red-hot electric filament, which
causes it to emit electrons that are attracted to the
plate. The control grid in the middle can controlthis
flow of electrons. By making it negative, you causethe
electrons to be repelled back to the cathode; by making
it positive, you causethem to be attracted toward the plate. Thus, by controlling
the grid current, you can control the on/off output of the plate.
Unfortunately, the tube was inefficient as a switch. Itconsumed a great deal of
electrical power and gave off enormous heat—a significant problemin the earlier
systems. Primarily becauseof the heat they generated, tubes were notoriously
unreliable—in larger systems, onefailed every couple of hours or so
Vacuumtubes are not important for computer memory anymorebecausewe
now use transistors. A long time ago however, the Vacuumtubes wereimportant
because they had the ability to regulate current flow through them, making them
a feasible means for computers.

3. Integrated Circuits: The Next Generation
The third generation of modern computers is known for using integrated
circuits instead of individual transistors. Jack Kilby at Texas Instruments and
Robert Noyce at Fairchild are both credited with having invented the integrated
circuit (IC) in 1958 and 1959. An ICis a semiconductor circuitthatcontains more
than one component on the same base (or substrate material), which areusually
interconnected without wires. The first prototypeICconstructed by Kilby at TI in
1958 contained only one transistor, severalresistors, and a capacitor on a single
slab of germanium, and it featured fine gold “flying wires” to interconnect them.
However, becausethe flying wires had to be individually attached, this type of
design was notpractical to manufacture. By comparison, Noycepatented the
“planar” ICdesign in 1959, whereall the components are diffused in or etched on
a silicon base, including a layer of aluminum metal interconnects. In 1960,
Fairchild constructed the first planar IC, consisting of a flip-flop circuit with four
transistors and fiveresistors on a circular die only about20 mm2
in size. By
comparison, the Intel Core i7 quad-core processor incorporates 731 million
transistors (and numerous other components) on a single 263 mm2
die!
Difference between vacuum tube and integrated circuit
An integrated circuit uses transistors instead of vacuumtubes. Transistors
and vacuumtubes can do the same things, in terms of how they alter the flow of
an electric currentin a circuit, however, vacuumtubes are much larger, and they
are also much less reliable, since they will eventually burn out, unlike transistors.
So with transistors you can do a lot more. Even though the earliest electronic
computer (ENIAC) was madewith vacuumtubes, nobody today would wantto
attempt to build a computer with vacuum tubes.