Analog vs Digital Computer
A computer is a device that can be programmed to execute a finite set of instructions in arithmetic or logical domains. Computers operate by sequentially executing the instructions, and these instructions can be changed when needed, giving the computer capability to solve problems general in nature rather than specific problem.
Computers can be operating based on mechanical or electrical principles and components. Generally a computer has a processing unit for performing logical or arithmetic operations and a memory to store the instructions.
More about Analog Computers
In analog computer, a continuously varying physical property is used to model the problem to be solved. The development of analog computers runs thousand years back in the human history. Oldest analog computer known to man is the Antikythera machine which is a device used to measure astronomical positions and its dated to 100BC. Astrolabes and slide rules are also examples of analog computers.
The analog computers reached its pinnacle during the late 18th century and early 19th century, where technological revolution inspired many analog computing devices. In the WWII, the new analog computers were used for encryption and gunfire assistance.
The electrically operated analog computers use the magnitude of continuous electrical signals such as voltage, current, and signal frequency for the operations and consist of circuits built with operational amplifiers, capacitors resistor and fixed function generators. These circuits performed summation, integration with respect to time, inversion, multiplication, exponentiation, logarithms, and division as basic mathematical operation to derive higher order results as the output.
Even today, the analog computers are used, but for much simpler task mainly due to the cost factors.
More about Digital Computers
Digital computers operate using discrete electric signals rather than continuous electric signals and have become the most predominant form of computers today because of their versatility and power. The first electronic digital computers were developed in the early 1940’s, in the United Kingdom and United States. They were large machines consuming large amounts of electric power and hence expensive, and mechanical computers had the advantage over digital computers.
When the smaller computers were built, the machines were designed for specific tasks, hence lacked the versatility. With the advancement of the semiconductor technology, the building blocks of the large computers were replaced with small less power consuming devices and digital computers advanced rapidly from there onwards.
Modern digital computers are built using integrated circuits, which houses billions of nano meter scale components in a small silicon piece not larger than a thumbnail, yet with the computational power of several thousand computers built in the early 20th century. Therefore, digital computers are used for all the advanced aspects of problem solving or computing.
What is the difference between Analog computers and Digital Computers?
• Analog computers work on measurement of continuous physical property hence the operating is most of the time linear and continuous, while digital computers use discrete electrical signals with two possible states.
• Analog computer may have no memory at all, while digital computers definitely require memory for its operation.
• Analog computers are slower in operation that the digital computers.
• Analog computers provide exact computation results while the digital computers lose the accuracy in the operations due to the discrete nature of signals.
• Analog computers are designed for specific single purpose, while digital computers are designed for general purposes.
Mark Shoemaker, BSEE, MBA, Six Sigma Black Belt says
I am a electrical engineer with 30 years experience. I have a comment on this statement:
“Analog computers provide exact computation results while the digital computers lose the accuracy in the operations due to the discrete nature of signals.”
The computation results of analog computers is not exact, depending on the tolerances of the electrical or mechanical components. Digital computers can have 20 or more bits per computed value. With 20 bits, the lsb for full scale of 10 volts is ~9.5u volt. Far better than analog. In addition, analog computers slow speed, slew rate do not provide an instant answer for inputs changing. Fast analog computers require high speed analog circuits to keep response time fast