Chapter 2

Question 1

Cray 1

Answer 1

• Seymour Cray didn’t care about CDC’s plans for diversification and went of and started his own company Cray Research
• 1976 first Cray 1 shipped to the Los Alamos laboratory
• the OS was simple as it usually ran a single job for days
• it became the new standard for nuclear weapons labs, aircraft designers and wether forecasters
• first machine to define the term supercomputer
• much more powerful and much faster than ENIAC
• very stylish
• built to computer and nothing else
• it went from exotic and expensive versions to the everyday consumer
• it remained the fastest computer until 1982, when it was succeeded by the Cray X-MP

Question 2

701 IBM

Answer 2

• 1952 IBM announces their first electronic product, the 701
• initially rented for 15k $ a month
• known as the defence calculator within IBM
• its capabilities were comparable to UNIVAC
• it had faster memory
• less efficient tape operations
• more reliable tape driver
• it was used for various tasks, from weapon design to financial reports

Question 3

704 IBM

Answer 3

• successor of 701
• 1954
• improvements:
  1. core memory
  2. hardware support for floating point arithmetic
  3. simplified programming with three index registers

Question 4

floating point

Answer 4

• not used with ENIAC, UNIVAC and IBM 701, as they deemed it unnecessary
• it simplifies programming needs for calculations with very large and very small numbers
• represents numbers in scientific notation, using a significand and exponent
• to implement it meant adding either more code or more hardware to support it
• pros: allows for faster and simpler programs
• cons: slows down the machine and adds expenses and makes the processor more complicated and expensive

Question 5

interrupts

Answer 5

• a lot of computing time was wasted on waiting for some data to arrive, constant looping to check
• adding interrupts allowed better utilisation of the computers resources and saved time
• instead of looping and checking the computer could get on with doing something useful
• input and output channels:
  1. allowed higher data throughput
  2. introduced in the IBM’s 709
  3. enabled actions such as printing, data copying and etc. without interrupting the main processor

Question 6

drum-based computers

Answer 6

• magnetic drums were cheaper to use for temporary memory
• they reemerged after WWII as reliable and inexpensive memory devices
• ERA engineers worked on the technology and refined it
• Model 1101: a programmable electronic computer around drum memory
• ERA’s big hit was the drum not the 1101 computer
• finding reliable memory at the time was one of the biggest challenges at the time
• cons:
  1. drum memory is slow
  2. providing input and output devices was a challenge
  3. there weren’t enough resources to create advanced follow up designs
• late 1950s: better drum computers
  1. The Librascope: smaller than the UNIVAC
  2. the G-15: influenced by Turing, difficult to program , but very fast

Question 7

ERA

Answer 7

Engineering Research Associates
Howard Engstrom and William Norris

Question 8

early compilers

Answer 8

• Grace Hoper wrote the first program that could be called a compiler, called it “automatic programming”
• compilers could translate high-level language into code that the computer could execute
• users could input equations in algebraic form and the compiler would handle the rest

Question 9

fortran

Answer 9

• formula translation language
• programming language for IBM’s 704
• invented by Backus: inspired by a basic problem of economics- programming and debugging costs were exceeding the cost of running the program + he was lazy
• a system that hid the inner details of the machine, letting the user focus on solving their problem not the machines problems
• keys to its success:
  1. familiar syntax, close to actual algebra
  2. clear and easy to read user manual
  3. performance: the compiler generated code that was as efficient as that written by humans

Question 10

SHARE and the OS

Answer 10

• a platform for the user group of the IBM 704
• it allowed users to collaborate and share their experiences, as well as software expertise and solutions
• it introduced a lot f practices and features which would later be used in open source projects
  1. it had shared libraries of routines
  2. bug reporting mechanisms
  3. collaborative development
• it developed the first monitors, which allowed automation of executing programs
• it allowed batch processing: when one program finished execution the monitor would trigger the next one without the need of human intervention
• SOS project: aimed to automate operator tasks and it was the first software to be called an operating system
• SOS provide: powerful assembler, batch control, output buffering, and a large number of input and output subroutines

Question 11

mathematical software

Answer 11

• 1960s fortran became essential for scientists and engineers involved in a lot of scientific computing
• there was a need for a efficient compilers
• WATFOR: fortran compiler, fast in-core compilation with good error diagnostics, especially useful for students debugging and speeding up execution
• challenge: ensuring mathematical accuracy of results obtained by scientific computing
  -> the computer being millions of times faster also meant it could make errors just as fast; scientist used outdated hand calulations methods which when ran on a computer result in errors
  -> it was important to have accurate results for real life approximations
• Eispack and Linpack software packages: offered ready to use subroutines for linear algebra
• challenge: ensuring effective execution of those subroutines on different computer architectures
• solution: seperate machine specific code into seperate libraries

Question 12

ALGOL

Answer 12

• algorithmic language
• it had major influence on computer research
• novelties:
  1. block structure (begin and end tags)
  2. recursion: procedures can call themselves
  3. nested procedures
  4. variable passing
  5. BNF notation: used to describe syntax of programming langauges
• introduced in 1958, in Zurich
• improved versio 1960
• compiler for ALGOL60: Dijkstra

Question 13

stacks

Answer 13

• Dijkstra generalised the stack data strcuture into a fundamental feature of a computer hardware and software (in ALGOL)
• the stack was used to store ALGOL procedures as well as local varaibles and data they needed
• when a procedure finished the procedure was automatically removed from the stack
• stack overflow: badly designed code
• implementing the stack on the computers at the time slowed them down alot
• useful for compiling programs into machine instructions
• Burroughs 5000: completely designed around the stack, it influenced computer architecture and software design

Question 14

transistors

Answer 14

• introduced by Bell Laboratories, replaced vacuum tubes
• pros:
  1. faster
  2. used less power
  3. more reliable
  4. smaller
• cons:
  1. expensive
• Philco’s SOLO: UNIVAC architecture but used transistors, first general-purpose transistorized computer to operate in the US
• Univac later delivered a smaller transistorised computer Solid State 80
• they marked the second generation of computers

Question 15

IBM 7090

Answer 15

• the air force insisted on transistorised machined, so IBM made a version of 709

Question 16

NASA, Ames

Answer 16

• Ames research center, California
• center for high-speed aerodynamics research
• served NASA in the space race
• IBM 7040 and IBM 7090

Question 17

IBM’s Stretch

Answer 17

• IBM wanted to beat UNIVAC, so they promised Los Alamos a much faster machine than the current IBM 704
• fetaures
  1. transistors
  2. assembled from a relatively small number of standard units
  3. instruction pipelining
  4. supplied with the biggest and fastest hard disk drives that IBM could provide
  5. first IBM computer to have multiprogramming
• 1960: announced it as IBM 7030 and set an initially very high price, however it didn’t live up to the promised fetaures and the price was halved
• first it seemed like a huge failure, but later most stretch machines went to the heaviest users of computer simulation

Question 18

virtual memory and the atlas

Answer 18

• ATLAS: designed at Manchester univeristy and built by Ferranti
• one of the most influential and fastest computers of the era
• it pioneered virtual memory
• virtual memory
  1. makes the computer faster
  2. makes the main memory seem bigger, by swapping data with a slower but larger storage medium like a disk
• atlas was designed for multiprogramming, so it could go on with a program while a page of memory was being loaded

Question 19

CDC

Answer 19

Control Data Corportoin
- founded by former members of ERA
- took over the supercomputer market after IBM announced the Stretch
- their first model 1604 was delivered to the US navy in 1960
- the CDC 6600 outperformed the Stretch
1. minimalistic design
2. faster
3. cooling pipes to stop overheating
4. excelled at arithmetic operations