What is a Computer?
In
its most basic form a computer is any device which aids humans in
performing various kinds of computations or calculations. In that
respect the earliest computer was the abacus, used to perform basic
arithmetic operations.
Every computer supports some form of input, processing, and output.
This is less obvious on a primitive device such as the abacus where
input, output and processing are simply the act of moving the pebbles
into new positions, seeing the changed positions, and counting.
Regardless, this is what computing is all about, in a nutshell. We input
information, the computer processes it according to its basic logic or
the program currently running, and outputs the results.
Modern computers do this electronically, which enables them to
perform a vastly greater number of calculations or computations in less
time. Despite the fact that we currently use computers to process
images, sound, text and other non-numerical forms of data, all of it
depends on nothing more than basic numerical calculations. Graphics,
sound etc. are merely abstractions of the numbers being crunched within
the machine; in digital computers these are the ones and zeros,
representing electrical on and off states, and endless combinations of
those. In other words every image, every sound, and every word have a
corresponding binary code.
While abacus may have technically been the first computer most people
today associate the word “computer” with electronic computers which
were invented in the last century, and have evolved into modern
computers we know of today.
ENIAC
First Generation Computers (1940s – 1950s)
First electronic computers used vacuum tubes, and they were huge and
complex. The first general purpose electronic computer was the ENIAC
(Electronic Numerical Integrator And Computer). It was digital, although
it didn’t operate with binary code, and was reprogrammable to solve a
complete range of computing problems. It was programmed using plugboards
and switches, supporting input from an IBM card reader, and output to
an IBM card punch. It took up 167 square meters, weighed 27 tons, and
consuming 150 kilowatts of power. It used thousands of vacuum tubes,
crystal diodes, relays, resistors, and capacitors.
The first non-general purpose computer was ABC (Atanasoff–Berry
Computer), and other similar computers of this era included german Z3,
ten British Colossus computers, LEO, Harvard Mark I, and UNIVAC.
IBM 1401
Second Generation Computers (1955 – 1960)
The second generation of computers came about thanks to the invention
of the transistor, which then started replacing vacuum tubes in
computer design. Transistor computers consumed far less power, produced
far less heat, and were much smaller compared to the first generation,
albeit still big by today’s standards.
The first transistor computer was created at the University of
Manchester in 1953. The most popular of transistor computers was IBM
1401. IBM also created the first disk drive in 1956, the IBM 350 RAMAC.
Third Generation Computers (1960s)
IBM System/360
The invention of the integrated circuits (ICs), also known as
microchips, paved the way for computers as we know them today. Making
circuits out of single pieces of silicon, which is a semiconductor,
allowed them to be much smaller and more practical to produce. This also
started the ongoing process of integrating an ever larger number of
transistors onto a single microchip. During the sixties microchips
started making their way into computers, but the process was gradual,
and second generation of computers still held on.
First appeared minicomputers, first of which were still based on
non-microchip transistors, and later versions of which were hybrids,
being based on both transistors and microchips, such as IBM’s
System/360. They were much smaller, and cheaper than first and second
generation of computers, also known as mainframes. Minicomputers can be
seen as a bridge between mainframes and microcomputers, which came later
as the proliferation of microchips in computers grew.
Fourth Generation Computers (1971 – present)
First microchips-based central processing units consisted of multiple
microchips for different CPU components. The drive for ever greater
integration and miniaturization led towards single-chip CPUs, where all
of the necessary CPU components were put onto a single microchip, called
a microprocessor. The first single-chip CPU, or a microprocessor, was
Intel 4004.
The advent of the microprocessor spawned the evolution of the
microcomputers, the kind that would eventually become personal computers
that we are familiar with today.
First Generation of Microcomputers (1971 – 1976)
Altair 8800
First microcomputers were a weird bunch. They often came in kits, and
many were essentially just boxes with lights and switches, usable only
to engineers and hobbyists whom could understand binary code. Some,
however, did come with a keyboard and/or a monitor, bearing somewhat
more resemblance to modern computers.
It is arguable which of the early microcomputers could be called a
first. CTC Datapoint 2200 is one candidate, although it actually didn’t
contain a microprocessor (being based on a multi-chip CPU design
instead), and wasn’t meant to be a standalone computer, but merely a
terminal for the mainframes. The reason some might consider it a first
microcomputer is because it could be used as a de-facto standalone
computer, it was small enough, and its multi-chip CPU architecture
actually became a basis for the x86 architecture later used in IBM PC
and its descendants. Plus, it even came with a keyboard and a monitor,
an exception in those days.
However, if we are looking for the first microcomputer that came with
a proper microprocessor, was meant to be a standalone computer, and
didn’t come as a kit then it would be Micral N, which used Intel 8008
microprocessor.
Popular early microcomputers which did come in kits include MOS
Technology KIM-1, Altair 8800, and Apple I. Altair 8800 in particular
spawned a large following among the hobbyists, and is considered the
spark that started the microcomputer revolution, as these hobbyists went
on to found companies centered around personal computing, such as
Microsoft, and Apple.
Second Generation Microcomputers (1977 – present)
As microcomputers continued to evolve they became easier to operate,
making them accessible to a larger audience. They typically came with a
keyboard and a monitor, or could be easily connected to a TV, and they
supported visual representation of text and numbers on the screen.
In other words, lights and switches were replaced by screens and
keyboards, and the necessity to understand binary code was diminished as
they increasingly came with programs that could be used by issuing more
easily understandable commands. Famous early examples of such computers
include Commodore PET, Apple II, and in the 80s the IBM PC.
The nature of the underlying electronic components didn’t change
between these computers and modern computers we know of today, but what
did change was the number of circuits that could be put onto a single
microchip. Intel’s co-founder Gordon Moore predicted the doubling of the
number of transistor on a single chip every two years, which became
known as “Moore’s Law”, and this trend has roughly held for over 30
years thanks to advancing manufacturing processes and microprocessor
designs.
The consequence was a predictable exponential increase in processing
power that could be put into a smaller package, which had a direct
effect on the possible form factors as well as applications of modern
computers, which is what most of the forthcoming paradigm shifting
innovations in computing were about.
Graphical User Interface (GUI)
Possibly the most significant of those shifts was the invention of
the graphical user interface, and the mouse as a way of controlling it.
Doug Engelbart and his team at the Stanford Research Lab developed the
first mouse, and a graphical user interface, demonstrated in 1968. They
were just a few years short of the beginning of the personal computer
revolution sparked by the Altair 8800 so their idea didn’t take hold.
Instead it was picked up and improved upon by researchers at the
Xerox PARC research center, which in 1973 developed Xerox Alto, the
first computer with a mouse-driven GUI. It never became a commercial
product, however, as Xerox management wasn’t ready to dive into the
computer market and didn’t see the potential of what they had early
enough.
It took Steve Jobs negotiating a stocks deal with Xerox in exchange
for a tour of their research center to finally bring the user friendly
graphical user interface, as well as the mouse, to the masses. Steve
Jobs was shown what Xerox PARC team had developed, and directed Apple to
improve upon it. In 1984 Apple introduced the Macintosh, the first
mass-market computer with a graphical user interface and a mouse.
Microsoft later caught on and produced Windows, and the historic
competition between the two companies started, resulting in improvements
to the graphical user interface to this day.
Meanwhile IBM was dominating the PC market with their IBM PC, and
Microsoft was riding on their coat tails by being the one to produce and
sell the operating system for the IBM PC known as “DOS” or “Disk
Operating System”. Macintosh, with its graphical user interface, was
meant to dislodge IBM’s dominance, but Microsoft made this more
difficult with their PC-compatible Windows operating system with its own
GUI.
Portable Computers
As it turned out the idea of a laptop-like portable computer existed
even before it was possible to create one, and it was developed at Xerox
PARC by Alan Kay whom called it the Dynabook and intended it for
children. The first portable computer that was created was the Xerox
Notetaker, but only 10 were produced.
The first laptop that was commercialized was Osborne 1 in 1981, with a
small 5″ CRT monitor and a keyboard that sits inside of the lid when
closed. It ran CP/M (the OS that Microsoft bought and based DOS on).
Later portable computers included Bondwell 2 released in 1985, also
running CP/M, which was among the first with a hinge-mounted LCD
display. Compaq Portable was the first IBM PC compatible computer, and
it ran MS-DOS, but was less portable than Bondwell 2. Other examples of
early portable computers included Epson HX-20, GRiD compass, Dulmont
Magnum, Kyotronic 85, Commodore SX-64, IBM PC Convertible, Toshiba
T1100, T1000, and T1200 etc.
The first portable computers which resemble modern laptops in
features were Apple’s Powerbooks, which first introduced a built-in
trackball, and later a trackpad and optional color LCD screens. IBM’s
ThinkPad was largely inspired by Powerbook’s design, and the evolution
of the two led to laptops and notebook computers as we know them.
Powerbooks were eventually replaced by modern MacBook Pro’s.
Of course, much of the evolution of portable computers was enabled by
the evolution of microprocessors, LCD displays, battery technology and
so on. This evolution ultimately allowed computers even smaller and more
portable than laptops, such as PDAs, tablets, and smartphones.
