History of Computing Devices

Long before electronic machines, people built calculating aids. Exams ask who made each device, in which year and what was new about it. Learn the table, then read the notes below it.

Timeline at a glance

Manual aids

• Abacus: the name comes from the Greek abax, "calculating board". The earliest form used pebbles on sand or dust. The Chinese Suanpan has 2 upper and 5 lower beads on each rod; the Japanese Soroban has 1 upper and 4 lower. It has been used for over 4,000 years, needs no electricity, and cannot store data or print results.
• Napier's Bones: ten rods numbered 0 to 9, laid side by side. They use the lattice method to reduce multiplication and division (and even square and cube roots) to simple addition and subtraction. Napier described them in Rabdologiae.

Mechanical machines

• Pascaline: built by Pascal as a teenager to help his father, a tax official. Interlocking gear wheels held the digits (up to 8 digits). Its Sautoir was the first automatic carry mechanism. Addition was direct; multiplication meant repeated addition. It inspired Leibniz and Babbage.
• Jacquard Loom: a hole in a card lifts the thread and makes a pattern; no hole leaves it down. Each card is one row of the design, and a chain of cards is a complete program. Changing the cards changes the output, exactly as changing software changes a modern computer. It ended the need for skilled assistants called drawboys and inspired Babbage.
• Punched card: used from 1801 to the 1970s as the main way to feed in and store data. Hollerith made it practical for the 1890 US census. The standard IBM card had 80 columns and 12 rows (80 characters). Magnetic tape, floppy disks and later media replaced it.
• Difference Engine: works by the method of finite differences, so it needs only addition. It could tabulate polynomials to 20 or more decimal places and printed its output, which cut copying errors. It was not programmable and had no memory. No. 1 (about 25,000 parts) was never finished because the engineering of the day could not match the precision needed; No. 2 was built correctly in 1991 at the Science Museum, London.
• Analytical Engine: four parts that match a modern computer.

It was the first design to join program control, memory, processing and output. It was never built for lack of money and technology. Ada Lovelace wrote its first algorithm (for Bernoulli numbers), which is why she is called the first programmer (and sometimes the "Mother of the Computer"), while Babbage is the Father of the Computer. She also guessed that such machines could one day handle symbols and even compose music.

Electromechanical and electronic machines

• Tabulating Machine: each card held one person's data (age, sex, occupation). Pins passed through the holes and dipped into mercury cups, completing a circuit that moved a counter forward; no hole meant no signal. The 1880 census had taken about eight years to tally, and this machine cut the time sharply. Hollerith's firm (1896) became IBM in 1924.
• Harvard Mark I: built at Harvard University with IBM engineers. It ran pre-set sequences automatically using relays, not vacuum tubes, and did scientific and wartime calculations. It is the bridge between mechanical and electronic machines.
• ENIAC: built for the US Army to compute ballistic tables. It used vacuum tubes throughout. It was not stored-program: to change the job, the operators had to rewire patch cables and set switches.
• EDVAC: put the program and data in the same memory and used binary instead of decimal. This is the von Neumann architecture, still used in every laptop and phone, and the reason one machine can run any software.
• EDSAC: the first stored-program machine to run a real program successfully. It used mercury delay-line memory (bits stored as sound pulses) and influenced LEO, the first business computer.
• UNIVAC I: sold to businesses and government for payroll and records. It stored data on magnetic tape rather than cards, and became famous for correctly predicting Eisenhower's win in the 1952 US election.