History of Modern Computers

Lecture for CPSC 5155

Edward L. Bosworth, Ph.D.

Columbus State University

Three Technical Calculators (At Peenemunde on June 5, 1943)

Definitions from 1933 Oxford English Dictionary (OED)

• “Calculator – One who calculates; a reckoner”.

• “Computer – One who computes; a calculator, reckoner; specifically a person employed to make calculations in an observatory, in surveying, etc.”

• There are no other definitions for these terms in this edition of the OED.

Computers in 1942

• In 1942, hundreds of women employed in the US as computers.

• They used mechanical desk calculators to solve numeric equations.

• Kathleen McNulty “You do a multiplication and when the answer appeared, you had to write it down and reenter it. … To hand compute one trajectory took 30 or 40 hours.”

“Computer” vs. “Operator”

• “Human agents will be referred to as ‘operators’ to distinguish them from ‘computers’ (machines)”. – George Stibitz, 1945

• Note the full name of the ACM, founded on September 15, 1947 as the Eastern Association for Computing Machinery.

• Even then, a computer might be a person.

The Classic Division by Generation

Here is the standard definition of computer generations. 1. The first generation (1945 – 1958) is that of vacuum tubes. 2. The second generation (1958 – 1966) is that of discrete transistors. 3. The third generation (1966 – 1972) is that of small-scale and medium-scale integrated circuits. 4. The fourth generation (1972 – 1978) is that of large–scale and very–large–scale integrated circuits. 5. The term “fifth generation” has been widely used to describe a variety of devices. There is no standard definition of the term; it is not often used.

Colossus

• This is a computer designed to break the German diplomatic code during WW-II

Harvard Mark II

• Note the mechanical calculator at left.

Computer Bug in 1945

• Contrary to some stories, this is not the origin of the use of the word “bug” for a problem.

The ENIAC

• Gloria Ruth Gorden and Ester Gerston programming the ENIAC.

The ENIAC Used Vacuum Tubes

• Two vacuum tubes of approximately the right vintage for use in the ENIAC

Women with Data Registers

• Patsy Simmers (ENIAC), Gail Taylor (EDVAC), Milly Beck (ORDVAC) and Norma Stec (BRLESC-I)

Why So Big?

• Console for IBM 7030 “Stretch” ~ 1957

The EDSAC-I

• This was built in England as a research project. Note the racks of vacuum tubes.

Pluggable Tube Module

• This is a vacuum tube module from the IBM 701 (1952).

Discrete Transistors

• Transistors were mounted on a module that could be plugged into a backplane.

• Note the “wiring” etched on the back of the module.

Another Circuit Board

• A Burroughs Computer of the late 1950’s.

Printed Circuit Board

Circuit Boards on a Backplane

Three Generations

• A plug module from the IBM 650 (1953)

• A transistor module from the 7090 (1956)

• A SSI module from the IBM 360 (1964).

PDP-10 Backplane

A Modern Motherboard

Wire Traces on Back

The EDSAC Memory

• Maurice Wilkes and a set of 16 mercury delay lines, each storing 32 words of 16-bits & parity.

Magnetic Core Memory

• This from an IBM Type 405 in 1952. Note the ferrite cores mounted on a 2-D wire mesh.

Core Memory on a PDP-8E

Modern Semiconductor Memory

The First Disk Drive

• IBM 305 RAMAC with IBM 350 Disk Drive • Fifty 24” disk drives held 5 million 7-bit words (total) • Introduced in September 1956.

IU (Instrument Unit) for Saturn V

• IBM Technicians in Huntsville AL at work. The man in the center is Mr. Joe Williams.

The IBM System 360

Installing the IBM 360/91 in 1969

Some Design Goals for the

System/360 • 1. To replace a number of very successful, but

incompatible, computer lines with a single computer family.

• 2. To provide “an expandable system that would serve every data processing need”. It was to excel at all “360 degrees of data processing”.

• 3. To provide a “strictly program compatible” family of processors, which would “ensure that the user’s expanding needs be easily accommodated by any model [in the System/360 family]”.

• The System/360 was announced on April 7, 1964.

Strict Program Compatibility

• IBM issued a precise definition for its goal that all models in the S/360 family be “strictly program compatible” .

• A family of computers is defined to be strictly program compatible if and only if a valid program that runs on one model will run on any model, with a few restrictions.

1. The program must be valid. “Invalid programs, i.e., those which violate the programming manual, are not constrained to yield the same results on all models”.

2. The program cannot require more primary memory storage or types of I/O devices not available on the target model.

3. The logic of the program cannot depend on the time it takes to execute. The smaller models are slower than the bigger models.

The Term “Architecture”

• The introduction of the IBM System/360 produced the creation and definition of the term “computer architecture”. According to IBM

• “The term architecture is used here to describe the attributes of a system as seen by the programmer,, i.e., the conceptual structure and functional behavior, as distinct from the organization of the data flow and controls, the logical design, and the physical implementation.”

• The IBM engineers realized that “logical structure (as seen by the programmer) and physical structure (as seen by the engineer) are quite different. Thus, each may see registers, counters, etc., that to the other are not at all real entities.”

Resource & Time Sharing

• In the 1970’s, computers were very expensive.

• The idea of “time sharing” was that many programmers could be connected to the computer at once, using video terminals.

• Allowing this drove several innovations: SPOOL for I/O devices, virtual memory, and process scheduling by the Operating System.

VM Shares the Computer Memory

• VM (Virtual Memory) is a service of the Operating System to allow sharing of the physical memory.

• Each process uses logical addresses which the OS maps to addresses in real physical memory.

• At left is the logical address space for MIPS.

Simultaneous Peripheral Operation On Line (SPOOL)

• Each process writes directly to the shared disk. The print manager controls the printer.

Time Sharing

• Each process runs for a fixed time or until it issues an I/O request. The CPU is shared.

A Modern Computer as a System

• A modern computer must be seen as a complete system: software & hardware.

• The hardware and software must be designed as a complete system.

• Software includes the operating system and compilers to convert higher level languages to the primitive assembly language.

“Home Computer of 2004”

• This is claimed to be taken from a 1954 edition of Popular Mechanics. It is a hoax. It is an altered picture of a trainer for submariners.

The Museum Display