Antikythera mechanical computer

 It is an acient Greek computer ,believed as first analog computer powered by Orrey. 

It was used to predict astronomical psoition and calendar in advance.

As the history says it was retrieved from the sea from a seawreck.

It was believed that it was invented by Greek scientist in 87 B.C.

Features:-

1. It contains two faces front and rear face.

   Front face:-

          ->The front face has two concentric scales.

          ->The first scale marks the Greek sign of the Zodiac.

         ->The outer scale which is moveable ring that fits the flush with the surface and runs in a channel, marked off with what appear to be days.

        ->The outer layer has been presumed to represent 365 days;however, recent reseearch shows soe evidence that it is mostly likely to divide into 354 intervals.

         ->If onesubscribes to the 354 days evidence, then most likely the interpretation is that ring is a manifestation of a 354 day lunar calendar.

      

photo credit:wikipedia.org

        ->The lunar calendar purpose was t serve daya to day indicator of successive lunations and have assisted with the interpretation of lunar  phase pointer and metonic and saros dials. 

   Rear face:

          ->This face contains five dials: two large displays the Metonic and Saros and three small indicators,called Olympiad dial.

          ->the metonic dial is the main upper dial on the rear of the mechanism. the metonic cycle defined in Physics is very closed to 19 tropical years. I

          ->It is therefore a convenient interval over which to convert between lunar and solar calendars.

        ->The metonic dial covers 235 months in five rotations of the dial.the pointer points to the synodic month,counted from new moon to new moon.

Turing Tumble

 This device was made by Alan Turing.It's a game that  demonstrates logic gates via mechanical computer. It's a teaching device primarily used for teaching on logical concept of computer programming.

It contains following major parts.

• Ball drops. The standard version uses two ramps which store a given number of balls. A switch at the bottom of the board triggers the release of the initial ball (typically blue), from the top left of the panel. The second ramp, on the right, contains red balls.
• Ramps and crossovers. The green ramp allows the balls to run down it one way and release it in only that direction, whereas the orange crossover lets balls traverse it to either side both ways, i.e. from right to left and vice versa.
• Interceptors. This black piece stops a ball.
• Bits. This is a one-bit storage: it changes direction when a ball rolls through, such that the next ball goes to the other side.
• Gear and gear bits. Gear bits are exactly like regular bits, but they can be connected to gears. The gears allow for linking state changes, thus integrally adding extra (abstract) power.

UNIVAC

 UNIVAC(UNIVersal Automatic Computer.) was made by J.P. Eckert  and J.W. Mauchly in 1961AD.

• It consisted of tape drives which could use either the old UNIVAC I metal tapes or the new PET film tapes, and some circuits that were transistorized (although it was still a vacuum tube computer)

  
  
  
  
  
  photo credit:wikipedia.org

• Its purpose was mostly for calculations of census or defense department.

• Its features are as follows:

1. It was 8 feet high,15 feet long and weighed about 15 tons.

2. The UNIVAC 90/60 Series first ran with Univac developed OS/9,

3. The UNIVAC Solid State was a 2-address, decimal computer.

EDSAC

 EDVAC(electronic delay storage automatic computer), was constructed by Maurice Wilkes and his team at the University of Cambridge Mathematical Laboratory in England.

•  It used mercury delay lines for memory, and derated vacuum tubes for logic. Input was via five-hole punched tape and output was via a teleprinter.

• It has various purposes such as to solve a differential equation relating to gene frequencies, was used to gather numerical evidence about solutions to elliptic curves, etc

Additionally it has the following features:

1. The EDSAC's memory consisted of 1024 locations, though only 512 locations were initially implemented.

2. only 17 bits were used.

   
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3. This device was the world's first practical stored program electronic computer.

4. It uses a binary number system.

5. Both input and output used paper type.

6. This machine was used to calculate a table of squares and a list of prime numbers.

EDVAC

 

EDVAC (Electronic Discrete Variable Automatic Computer) was made by J.W Mauchy and J.P. Eckert in 1952AD.

Physically, the computer comprised the following components:

• He was the first to introduce the stored program concept in a computer.

• It used a binary number system rather than decimal numbers for its operation.

• It had almost 6,000 vacuum tubes and 12, 000 diodes and consumed 56 KW of power.

• It covered 490 square foot of floor space and weighed nearly 7 tons.

• The machine requires 30 personnel to operate.

• This machine ran till 1961 at a research laboratory.

• A magnetic tape reader-recorder (describes this as a wire recorder.)

• A control unit with an oscilloscope.

• A dispatcher unit to receive instructions from the control and memory and direct them to other units.

• A computational unit to perform arithmetic operations on a pair of numbers at a time and send the result to memory after checking on a duplicate unit.

• A timer.

  
  photo credit:edn.com

• A dual memory unit consisting of two sets of 64 mercury acoustic delay lines of eight words capacity on each line.

• Three temporary tanks each holding a single word.

• The EDVAC was a binary serial computer with automatic addition, subtraction, multiplication, programmed division and automatic checking with an ultrasonic serial memory.

Additionally it was the computer with

1. EDVAC was a binary serial computer.

2. It had an ultrasonic serial memory capacity of 1,000 44-bit words.

3. It consumed 56 kW of power.

ENIAC

 

• ENIAC(electronic numerical integrator and calculator) was made during in 1946 for the U.S.Army. it was made by John William Mauchly & J.Presper Eckert.

• ENIAC contained 17,468 vacuum tubes, 7,200 crystal diodes, 1,500 relays, 70,000 resistors, 10,000 capacitors and around 5 million hand-soldered joints.

• ENIAC was designed to calculate artillery firing tables for the United States Army's Ballistic Research Laboratory.

• Its main features are as follows:

1. It is the first electronic general-purpose computer.

2. consumed 150 kW of power.

   
   photo credit: edn.com

3. It had no moving parts except the input and output.

4. ENIAC was developed for military needs and was used for many years to solve ballistics (fire weapons) achieved problems.

5. The addition of two numbers was achieved in 200 microseconds and multiplication in 2000 microseconds.

6. It weighed more than 30 short tons (27 t), was roughly 8 by 3 by 100 feet (2.4 m × 0.9 m × 30 m), took up 1800 square feet. 

ABC computer

 

• ABC, the first electronic digital computer, was invented by John v. Atanasoff and his assistant Clifford Berry during 1937-1942.

• It consisted of 18000 valves and other45 valves with wires.

• It was build for calculation of difficult equations and other mathematical equations.

• Its main features are as follows:

1. it uses binary digits to represent all numbers and data.

2. Organizing a system in which computation and memory are separated.

3. Performing all calculations using electronics rather than wheels, ratchets, or mechanical switches.

   
   
   
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4. This machine was the first to store a change on a capacitor, which is how today computers store information in their main memory (RAM).

5. It used 45 vacuum tubes for internal logic and capacitors for storage.