Historical Computers
The following material is from the
Computer History Museum
http://www.computerhistory.org
1944-Harvard Mark-1
Conceived by Harvard
professor Howard Aiken, and
designed and built by IBM,
the Harvard Mark-1 was a
room-sized, relay-based
calculator.
The machine had a fifty-foot
long camshaft that
synchronized the machine’s
thousands of component parts.
The Mark-1 was used to
produce mathematical tables
but was soon superseded by
stored program computers.
1946-February, the public got
its first glimpse of the ENIAC, a
machine built by John Mauchly
and J. Presper Eckert that
improved by 1,000 times on the
speed of its contemporaries.
Start of project:
1943Completed:
1946Programmed:plug board
and switches
Speed:5,000 operations per
second
Input/output:cards, lights,
switches, plugs
Floor space:1,000 square feet
Project leaders:John Mauchly
and J. Presper Eckert.
Punch Cards
The IBM card format, designed in 1928, had rectangular holes, 80 columns with 12
punch locations each, one character to each column. Card size was exactly 187.325 by
82.55 mm.
The top two positions of a column were called zone punches, 12 (top) and 11. These
often encoded plus and minus signs. The lower ten positions represented (from top to
bottom) the digits 0 through 9. Originally only numeric information was coded, with 1 or 2
punches per column: digits (digit [0-9]) and signs (zone [12,11] ).
Later, codes were introduced for upper-case letters and special characters. A column
with 2 punches (zone [12,11,0] + digit [1-9]) was a letter; 3 punches (zone [12,11,0] +
digit [2-4] + 8) was a special character.
IBM
Keypunch
Machine 026
http://www.tietokonemuseo.saunalahti.fi/eng/laite_eng.htm
1950+ Early computers were limited
because there was no way to build
reliable and high-speed memory memory.
Magnetic core solved these problems and
subsequently became the dominant form
of computer memory for more than 20
years.
Core memory uses a 3-dimensional array
of tiny ferrite rings to store data or
programs.
Each ring stores a single bit and is
magnetized in either a clockwise or
counterclockwise direction, representing a
“0” or a “1” respectively. The cores are
magnetized by a current flowing in wires
that are threaded through each core. The
direction of the current determines the
direction of the magnetization
In 1953, Jay Forrester invented “coincident current addressing”, which made core memory practical.
In this scheme, the current needed to magnetize the core is split between two wires (one horizontal,
the other vertical). Only the core at the intersection of two electrified wires will change magnetization.
In order to read a single core, a third wire is threaded through all the cores of a plane. When a core is
magnetized to a “0,” a pulse occurs on this sense wire only if that core had been a “1” and not if it was
already a “0.” This is destructive readout, since if it was a “1” it now needs to be rewritten.
Consequently, it takes two cycles to read core memory, one to read the contents and another to reset
it to its original state.
1951-The UNIVAC I delivered to the
U.S. Census Bureau was the first
commercial computer to attract
widespread public attention.
Although manufactured by
Remington Rand, the machine often
was mistakenly referred to as the
"IBM UNIVAC."
Remington Rand eventually sold 46
machines at more than $1 million
each.F.O.B. factory $750,000 plus
$185,000 for a high speed printer.
Speed:1,905 operations per second
Input/output:magnetic tape, unityper,
printer
Memory size:1,000 12-digit words in
delay lines
Memory type:delay lines, magnetic
tape
Technology:serial vacuum tubes,
delay lines, magnetic tape
Floor space:943 cubic feet
Cost:F.O.B. factory $750,000 plus
$185,000 for a high speed printer
Project leaders:J. Presper Eckert
and John Mauchly
1961-IBM 1301 Disk Storage
Unit is released.
The IBM 1301 Disk Drive
was announced on June
2nd, 1961 for use with IBM’s
7000-series of mainframe
computers.
Maximum capacity was 28
million characters and the
disks rotated at 1,800 R.P.M.
The 1301 leased for $2,100
per month or could be
purchased for $115,500.
The drive had one read/write
arm for each disk as well as
flying heads, both of which
are still used in today’s disk
drives.
1962 - IBM 1311 Disk Storage
Drive is announced.
Announced on October 11,
1962, the IBM 1311 was the
first disk drive IBM made with
a removable disk pack.
Each pack weighed about ten
pounds, held six disks, and
had a capacity of 2 million
characters.
The disks would rotate at
1,500 RPM and were
accessed by a hydraulic
actuator with one head per
disk.
The 1311 offered some of the
advantages of both tapes and
disks.
1963 - ASCII — American
Standard Code for Information
Interchange — permitted
machines from different
manufacturers to exchange
data.
ASCII consists of 128 unique
strings of ones and zeros.
Each sequence represents a
letter of the English alphabet, an
Arabic numeral, an assortment
of punctuation marks and
symbols, or a function such as a
carriage return.
Transistors and Transistor based
circuit boards
1964 - IBM announced the
System/360, a family of six
mutually compatible
computers and 40
peripherals that could work
together.
The initial investment of $5
billion was quickly returned
as orders for the system
climbed to 1,000 per month
within two years.
At the time IBM released
the System/360, the
company was making a
transition from discrete
transistors to integrated
circuits, and its major
source of revenue moved
from punched-card
equipment to electronic
computer systems
1966 - Hewlett-Packard
entered the general purpose
computer business with its
HP-2115 for computation,
offering a computational
power formerly found only in
much larger computers.
It supported a wide variety of
languages, among them
BASIC, ALGOL, and
FORTRAN.
Magnetic Drums
Developed in the 1950s, magnetic drums were the first mechanical “direct access” storage
devices. Typically, drums were made of a nickel-cobalt substrate coated with powdered
iron. Data was recorded by magnetizing small surface regions organized into long tracks of
bits. Unlike tape, data could be accessed randomly without having to skip large sections of
unwanted information. Prior to the development of magnetic core memory, drums were
used as main memory for several low cost computers such as the IBM 650, LGP-30 and
Bendix G-15.
Magnetic Tapes
Magnetic tape has been used to store digital information since at least 1951 when Presper Eckert and
John Mauchly used it in the UNIVAC I computer. Their tape was made of metal, but later tapes have
been made mostly of plastic.
Some users of punched cards were initially reluctant to use tape because they could no longer see their
data. IBM’s invention of the “vacuum channel” tape drive and improved magnetic materials resulted in
reliable large-capacity tapes, which even reluctant customers eventually adopted.
Tape data formats vary widely, and bit density has increased dramatically. Tape has now been largely
replaced by hard disks for secondary storage, but it is still used for backing up of data.
Magnetic Disks
In the 1950s, engineers attempted to develop a device that would provide efficient secondary storage,
but also, unlike tape drives, provide random access to data. IBM succeeded by inventing the magnetic
disk at their San Jose laboratories in 1956. Developed as part of a larger system known as RAMAC,
the first Model 350 disk drive contained 50 24-inch diameter disks and stored a total of five
megabytes. IBM later added removable disk platters to its drives as featured on the IBM 1311. These
platters provided archival data storage.
IBM also was the first to hermetically seal both platters and read/write heads in a single enclosure in
its Model 3340 Winchester disk drive. Today, all disk drive manufacturers employ this design
convention. A sampling of the wide variety of disk shapes and sizes can be seen here.
1972 – PDP 11/40 Minicomputer
DEC developed the PDP-11 as a family of
16-bit minicomputers that could grow with
customers as their computing needs
increased.
From the first PDP- 11/20 in 1970 through
the PDP-11/94 in 1990, DEC produced a
variety of compatible machines and sold
over 500,000.
Much like the 12-bit PDP-8 before it, DEC
further integrated the PDP-11 family until
in 1982 it had placed one of its largest
models, the PDP-11/70, on two largescale integrated circuits.
Since the PDP-8 and PDP-11 systems
were subject to export restrictions, Soviet
bloc computer companies commonly
cloned the systems and packaged them
under different names.
Memory Type:Core
Speed:1.25 MHz +
Memory Size:56K+
Cost:$20,000 +
Memory Width:(16-bit)
1977 - The Commodore PET
(Personal Electronic
Transactor) — the first of
several personal computers
released in 1977 — came fully
assembled and was
straightforward to operate, with
either 4 or 8 kilobytes of
memory, two built-in cassette
drives, and a membrane
"chiclet" keyboard.
1977 - The Apple II
became an instant
success when released in
1977 with its printed
circuit motherboard,
switching power supply,
keyboard, case assembly,
manual, game paddles,
A/C powercord, and
cassette tape with the
computer game
"Breakout."
When hooked up to a
color television set, the
Apple II produced brilliant
color graphics.
1981- IBM Personal Computer
Although IBM’s first personal computer arrived nearly ten years after others were
available, the IBM Personal Computer (PC) instantly legitimized and expanded the
market.
Unlike most other contemporary IBM products, the PC incorporated both hardware (the
Intel 8088 microprocessor) and software made by other companies. IBM published
design details in their manuals that encouraged others to make copies or “clones” of the
original machine, often with improved functionality. The IBM PC architecture quickly
became an industry standard.
Memory Type:Semiconductor
Speed:4.77 MHz
Memory Size:16K
Cost:$1,565
Memory Width:(8-bit)
1982 -Commodore introduces
the Commodore 64.
The C64, as it was better
known, sold for $595, came with
64KB of RAM and featured
impressive graphics.
Thousands of software titles
were released over the lifespan
of the C64.
By the time the C64 was
discontinued in 1993, it had sold
more than 22 million units and is
recognized by the 2006
Guinness Book of World
Records as the greatest selling
single computer model of all
time.