A History Of
Computers
Prologue: Before
Electronic Computers
To understand how computers
evolved, we must first look at the
pre-electronic era.
Mechanical Calculators
(1600s–1800s)
1623:
Wilhelm Schickard
builds the first
mechanical calculator.
1642:
Blaise Pascal’s
Pascaline performs
addition/subtraction.
1801:
Joseph Marie Jacquard’s
punched-card loom
automates weaving—
a precursor to
programmable machines.
The First "Computers"
Were Humans
The term computer
originally referred
to people (often
women) who performed
calculations
manually.
1843:
Ada Lovelace writes the
first algorithm for Charles
Babbage’s Analytical Engine
(never built), making her
the first programmer.
Electromechanical Era
(Late 1800s–1930s)
1890:
Herman Hollerith’s
tabulating machine
(using punch cards)
speeds up the U.S.
Census.
1936:
Alan Turing proposes
the Turing Machine,
a theoretical model
for computation.
1937:
Konrad Zuse builds the
Z1, the first binary
electromechanical
computer.
Problem: These machines were
slow, mechanical, and limited—setting
the stage for electronic computing.
1st Generation
(1942–1959):
The Birth of
Electronic Computing
The Age of Vacuum Tubes
1941:
The Atanasoff-Berry
Computer (ABC) solves
linear equations using
vacuum tubes.
1944:
Harvard’s Mark I
(electromechanical)
aids WWII calculations.
1945:
ENIAC (Electronic
Numerical Integrator and
Computer) is built for
artillery calculations—
17,000 vacuum tubes,
weighed 27 tons!
Key Innovation:
Vacuum tubes for computation and memory.
Machine language (binary code).
What Led to the Innovation?
WWII demands: Needed fast calculations for
artillery trajectories, code-breaking (e.g.,
ENIAC for the U.S. Army).
Replaced mechanical/electromechanical computers
(e.g., punch-card systems).
Impact at the Time:
Enabled large-scale scientific/military
calculations (e.g., atomic research).
Limitations:
Size: Room-sized, consumed 150kW+ of power.
Heat/Reliability: Vacuum tubes burned out
frequently.
Cost/Maintenance: Only governments/universities
could afford them.
Transition: The search for something
smaller, faster, and more reliable
led to the next leap.
2nd Generation
(1960–1965):
Transistors Take
Over
The Transistor Revolution
1947:
Bell Labs invents the
transistor—a tiny switch
with no moving parts.
1954:
First transistor radio
(portable electronics
begin).
1960s:
IBM 1401 and Honeywell 200
dominate business
computing.
Key Innovation:
Transistors replaced vacuum tubes (smaller,
faster, no overheating).
Assembly languages (more human-readable than
binary).
What Led to the Innovation?
Invented transistors for telecommunications.
Cold War/space race: Needed smaller, more
reliable computers for missiles/satellites.
Impact at the Time:
Business adoption: IBM 1400 series for
payroll/data processing.
Scientific research: Faster simulations (e.g.,
weather forecasting).
Limitations:
Still expensive for individuals.
Cooling needed (though less than 1st gen).
Limited software (mostly custom-written).
Transition: The next challenge?
Making computers even
smaller and cheaper.
3rd Generation
(1965–1971):
Integrated
Circuits
The Silicon Revolution
1958:
Jack Kilby (Texas
Instruments) invents the
integrated circuit (IC).
1965:
Gordon Moore predicts
Moore’s Law (transistors
double every 2 years).
1969:
Apollo 11 lands on the
moon with IC-based
guidance computers.
Key Innovation:
Integrated Circuits (ICs)—multiple transistors
on a silicon chip.
High-level languages (COBOL, FORTRAN).
What Led to the Innovation?
NASA/Space Race: Needed lightweight, reliable
computers for Apollo missions.
Corporate R&D: Texas Instruments/Intel
miniaturized circuits.
Impact at the Time:
Minicomputers (e.g., PDP-8): Affordable for
universities/small businesses.
Time-sharing: Multiple users could access one
computer.
Limitations:
Still not personal (shared use in
institutions).
Limited graphics/multimedia.
Transition: The next goal?
A computer in every home.
4th Generation
(1971–1990):
The Microprocessor
& Personal Computers
The PC Revolution
1971:
Intel’s 4004 (first
microprocessor) fits
a CPU on one chip.
1975:
Altair 8800 (kit
computer) inspires Bill
Gates & Paul Allen.
1977:
Apple II, Commodore PET—
first consumer PCs.
1981:
IBM PC standardizes the
market.
Key Innovation:
Microprocessors (thousands of transistors on one
chip, e.g., Intel 4004).
Personal Computers (PCs): Apple I (1976), IBM PC
(1981).
What Led to the Innovation?
Consumer electronics boom: Calculators, digital
watches needed cheap chips.
Counterculture/hacker movement: DIY computing
(e.g., Homebrew Computer Club).
Impact at the Time:
PC Revolution: Computers in homes/schools.
Early networking: ARPANET (precursor to the
internet).
Limitations:
Limited memory/storage (early PCs had KBs of
RAM).
No internet/connectivity for most users.
Transition: The next phase?
Networking and multimedia.
5th Generation
(1990–2020s):
The Connected
World
1990s: The Internet Age
1993: Mosaic browser popularizes the web.
1995: Windows 95 brings GUI to masses.
1998: Google revolutionizes search.
2000s: Mobility & Multimedia
2001: iPod → digital music revolution.
2007: iPhone → smartphone era.
2010s: The Cloud era
Cloud computing (AWS)
social media (Facebook, Twitter).
2020s: Extensive Computing
AI and LLM (Chatgpt, DeepSeek).
IoT (smart homes, wearables).
Quantum computing (early stages).
Key Innovation:
ULSI (Ultra-Large-Scale Integration): Millions of
transistors/chip.
AI, machine learning, natural language processing
(e.g., Siri, ChatGPT).
What Led to the Innovation?
Internet/globalization: Needed faster data
processing.
Big Data: AI thrives on massive datasets (e.g.,
Google search algorithms).
Impact at the Time:
Smart devices: Phones, IoT, cloud computing.
Automation: Robotics, self-driving cars.
Limitations:
Ethical concerns: Privacy, Bias in AI, job
displacement.
Energy consumption: Data centers use ~1% of
global electricity.