History of Computers: From Abacus to Analytical Engine

History of Computers

Abacus or Soroban (5,000 years ago by the Chinese)
- First manual calculating device to count large numbers.
Pascaline or Arithmetic Machine (1442 - Blaise Pascal)
- Box with 8 movable wheels with each wheel having ten teeth 0-9.
- Used to calculate taxes.
- Similar to old rotary phones.
Leibniz device or Step Reckoner (Gottfried Wilhelm)
- Designed in 1671.
- Built in 1673.
- Carried out multiplication by repeated addition and shifting.
- Decimal form.
Baggage Machine (1791-1871)
- Developed by Charles Baggage (Father of the Modern Calculator).
- Difference & Analytic Engines
  - Difference engine has 2 designs: 1st in 1821 designed to calculate and tabulate polynomial functions.
  - First complete design for automatic calculating engines.
  - Improved design (1847-1849) improved version of the first one.
  - Analytical Engine (1834) a general-purpose programmable computing engine that used punched cards.
    - This engine has many essential features of modern digital computers.
Hollerith Machine (1888 Herman Hollerith)
- Consists of electrically operated components that captured and process data by reading holes on paper punched cards.
- Used for census taking.
- Sorting table.
Harvard Mark I or the IBM Automatic Sequence Controlled Calculator (ASCC)
- Electromechanical computer.
- Designed by Howard Aiken.
- Built by IBM in 1944.
- First to solve arbitrary mathematical problems.
- Inspired by the Baggage Machine.
- Used punched tape and card devices, calculate and print mathematical tables.
Electronic Numerical Integrator and Computer (ENIAC)
- Developed during WWII by Eng. J. Presper Eckert Jr, John Mauchly.
- Used for computing the values of artillery range tables.
- Introduced conditional branching.

Terms

Von Neumann Architecture
- Proposed by John von Neumann in 1954.
- Stored program computer concept.
- Features include: control unit, arithmetic & logic unit, memory unit, registers, I/O.
UNIVERSAL AUTOMATIC COMPUTER (UNIVAC)
- Built by the same team as ENIAC.
- Developed from 1947 to 1951.
- Used by government and businesses.
- Tabulated the 1950 population census.
- Tabulated the 1954 economic census.
Transistors and Microprocessors
- Transistor - Invented in 1956 by John Barden, William Shockley, Walter Braittain.
  - Replaced vacuum tubes.
- Microprocessor
  - First microprocessor Intel 4004 - 1971.
  - Developed by INTEL in 1968.
IPO - stands for Input, Process, Output.
CPU - Central Processing Unit (microprocessor)
VM - Virtual Machine
- A virtual machine takes up space.
- Virtual box = Virtual Machine
Printer:
- 1. Non-impact
  - Inkjet
  - Laser
- 1. Impact
  - 80
  - 132
  - Line printer
LED - Light Emitting Diode
LCD - Liquid Crystal Display
Capacity:
- 1. Low cap
- HD - 2. High cap
- Made frag
SSD - Solid State Drive, no need to defrag.
Linux - similar to SSD in terms of performance
Program - A set of instructions.
Operating System - Essential for a computer to function.
Interface
- a. DOS
  - Command line interface
  - Graphical user interface
- b. Windows 95
- c. Linux
- d. Android
- e. IOS
Application
- a. Word processing
  - PPT
  - Word
- b. Spreadsheet
  - Excel
- c. Presentation
- d. Database

Licensing:

Proprietary
- Does not include source code.
FOSS
- Free open source software.
Programming software
- B - Beginners
- A - All purpose
- S - Symbolic
- I - Interaction
- C - Code

Number Systems

Decimal
- Base 10.
- Uses digits 0-9.
Octal
- Base 8.
- Uses digits 0-7.
HEXADECIMAL (N16)
- Base 16.
- Uses digits 0-9 and A-F (A = 10, B = 11, C = 12, D = 13, E = 14, F = 15).
Binary (N2)
- Base 2.
- Uses digits 0 and 1.

Base Conversion

Minimum value: Base - 1
Maximum value: Base - 1
- In calculations and counting, you cannot exceed the maximum value for the base.

Division Method (for converting whole numbers)

Dividing by target base
- Divide the number repeatedly by the target base until the quotient reaches 0 (whole number).
- The remainders, read from bottom to top, form the converted number.
Example (converting 26 to binary):
- 26 / 2 = 13 (remainder 0)
- 13 / 2 = 6 (remainder 1)
- 6 / 2 = 3 (remainder 0)
- 3 / 2 = 1 (remainder 1)
- 1 / 2 = 0 (remainder 1)
- Binary equivalent of 26: 11010

Multiplication Method (for converting fractions)

Multiplying by the base
- Multiply the fraction by the base until it becomes a whole number (or until you reach a desired level of precision).
- The whole number parts from each multiplication, read from top to bottom, form the converted number.
Example (converting 0.25 to binary):
- 0.25 x 2 = 0.5 (whole number part = 0)
- 0.5 x 2 = 1.0 (whole number part = 1)
- Binary equivalent of 0.25: 0.01

Combined Approach (for converting numbers with both whole and fractional parts)

Convert the whole number part using the division method.
Convert the fractional part using the multiplication method.
Combine the results.
Example (converting 107.5 to octal):
- Whole number part (107):
  - 107 / 8 = 13 (remainder 3)
  - 13 / 8 = 1 (remainder 5)
  - 1 / 8 = 0 (remainder 1)
  - Octal equivalent of 107: 153
- Fractional part (0.5):
  - 0.5 x 8 = 4.0 (whole number part = 4)
  - Octal equivalent of 0.5: 0.4
- Combined result: 107.5 (decimal) = 153.4 (octal)