Mechanical Analogue Computers & Charles Babbage

Mechanical Analogue Computers

• The differential analyser was a mechanical analog computer used for solving differential equations.
• It used wheel-and-disc mechanisms to perform integration.
• Sir William Thomson discussed the possibility of such devices but was limited by insufficient torque in ball-and-disk integrators.
• Torque amplifiers allowed these machines to function.
• Vannevar Bush and others developed mechanical differential analysers in the 1920s.
• Spanish engineer Leonardo Torres Quevedo developed analog machines to solve polynomial equations in the 1890s, published in 1901 by the Paris Academy of Sciences.

Charles Babbage

• Considered the "father of the computer", Charles Babbage is credited with originating the concept of the programmable computer.
• In the early 19th century, he conceptualised and designed the first mechanical computer.
• Babbage's Difference Engine was designed to calculate mathematical tables and aid in navigational calculations.
• In 1833 he proposed the Analytical Engine, a more general design that allowed for programmable sequences of calculations.
• The Analytical Engine was to use punched cards, similar to those used in Jacquard Looms to control designs, as input.
• Output was designed to be produced through printers, curve plotters, and a bell.
• The Analytical Engine was also intended to be able to punch numbers onto cards for later use.

Computer Architecture

• A computer consists of interconnected parts, often connected through buses made up of groups of wires.
• These parts contain thousands to trillions of electrical circuits.
• Each circuit represents a bit of information (a binary digit), representing a "1" when on, and a "0" when off.
• Circuits are arranged in logic gates allowing control of other circuits.

Input Devices

• Input devices send unprocessed data to the computer, where it is processed and sent to output devices.
• They can be either hand-operated or automated.
• Input device examples:
  • Computer keyboard
  • Digital camera
  • Graphics tablet
  • Image scanner
  • Joystick
  • Microphone
  • Mouse
  • Overlay keyboard
  • Real-time clock
  • Trackball
  • Touchscreen
  • Light pen

Output Devices

• Output devices are the means by which a computer provides results.
• Output device examples:
  • Computer monitor
  • Printer
  • PC speaker
  • Projector
  • Sound card
  • Video card

Control Unit

• The control unit (also called a control system or central controller) manages the components of a computer.
• It decodes program instructions, translating them into control signals that activate other parts of the computer.
• Control units in advanced computers can rearrange the order of instructions to improve performance.
• The program counter, a register in the CPU, keeps track of the location of the next instruction to be read from memory.
• The control unit performs the following functions:
  • Reads code from the memory location indicated by the program counter.
  • Decodes the instruction.
  • Increments the program counter to the next instruction.

Multiprocessing

• Some computers distribute work across multiple CPUs in a multiprocessing configuration.
• Multiprocessing was once common only in powerful computers such as supercomputers, mainframes, and servers.
• Now, multiprocessor and multi-core (multiple CPUs on a single integrated circuit) computers are common in personal computers and even lower-end markets.

Supercomputers

• Often have unique architectures that differ from general-purpose computers.
• Feature thousands of CPUs and specialized hardware.
• Designed for specialized tasks, like large-scale simulations, graphics rendering, and cryptography.

Software

• Software refers to the non-physical parts of a computer, such as programs, data, protocols, etc.
• It consists of encoded information or computer instructions, in contrast to the hardware.
• Includes computer programs, libraries, and data (e.g., documentation, digital media).
• Typically divided into system software and application software.
• Hardware and software are interdependent.
• When software is stored in unmodifiable hardware (e.g. BIOS ROM), it is sometimes called "firmware".

The word "computer"

• The word "computer" originated in the mid 17th century, referring to a person who performs calculations.