Copyright (C) 2017, 2018, H. Conrad Cunningham

Acknowledgements: I created these slides in Fall 2017 and revised them in Summer 2018 to accompany what is now Section 1.2, Evolving Computer Hardware Affects Programming Languages, of the book Exploring Languages with Interpreters and Functional Programming.

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Lecture Goals

• Survey the evolution of computers since the 1940’s

• Examine how this affects the evolution of programming languages

First “Modern” Computers

• ENIAC (Electronic Numerical Integrator and Computer) completed 1946

  • cost $500,000 = $7,000,000 today
  • weighed 30 tons, occupied space of small house
  • used 160 kilowatts of electricity
  • had no main memory, 20 accumulators (10 decimal digits)
  • later added 100 words of core
  • used punch cards for external memory
  • were not very reliable
  • designed for military purposes, small perceived market

Computers 70 Years Later (1)

• Processors

  • are much smaller and faster
  • use much less power
  • cost much less money (if mass produced)
  • operate much more reliably
  • are everywhere!

Computers 70 Years Later (2)

• Main memory

  • larger in capacity
  • smaller in physical size
  • faster in access speed
  • less costly
  • less power consumption
  • more reliable

Computers 70 Years Later (3)

• Processors per machine

  • from one to many per machine
  • from one to several per chip
  • from none to several specialized processors
  • trend continues because approach to physical limits

Computers 70 Years Later (4)

• External storage

  • random access
  • larger in capacity
  • smaller in size
  • faster in access time
  • less expensive

Computers 70 Years Later (5)

• Processors per person

  • from one for many people
  • to many computers per person

• Physical presence

  • from isolated in locked rooms
  • to deployed everywhere

Computers 70 Years Later (5)

• Range of applications

  • from a few specialized applications
  • to almost all aspects of human activities

• Cost of human staff to support?

  • probably increased some!

Effects on Practice (1)

• Computers versus humans

  • early computers expensive, human workers relatively inexpensive
  • current computers inexpensive, human workers relatively expensive
  • from optimizing computers to optimizing humans

• Processor time and memory

  • early computer time and memory precious
  • current computer time and memory relatively plentiful
  • THUS: devote significant computing resources to increase human productivity

Effects on Practice (2)

• Problem size

  • early computers for a few small problems (but larger than what easy manually)
  • current computers for many and much larger problems (impossible manually)
  • execution efficiency still important in production
  • THUS: devote significant computing resources to increase programmer productivity and effectiveness

Effects on Practice (3)

• Computers versus applications

  • early days many applications and users share computer
  • currently many computers can support one application or user
  • THUS: use cheap computers to increase productivity and range of application

• Security

  • early computers secure in locked rooms
  • current computers on network with diverse applications and users
  • THUS: security has become thorny issue

Programming Languages

• First using cables and switches

• Machine language

• Assembly language

• High-level languages appeared in mid-1950s

  • First compiler in 1957 (Fortran)

Languages 60 Years Later

• Allocate/deallocate memory automatically rather than manually

• Interpret rather than compiled to machine code

• Exploit multicore systems rather than just one processor

• Incorporate declarative features rather than imperative

  • to optimize programmer productivity
  • to improve reliability and security
  • to better use multicore capabilities

Key Ideas

• Computer hardware has changed greatly since the 1940’s

• Computing practice has changed as a result.

• Programming languages have evolved to accommodate the evolving hardware and usage patterns.