The original computer developed by UNIVAC was funded by the military to solve problems such as the trajectories of shells. Sperry thought the demand was 4 and so did not push the marketing of computers. IBM saw the business possibilities of computers and developed its reputation not so much by product innovation, but by service and support. The computer market developed in the Fortune 500 companies and has progressively moved to smaller and smaller companies. Currently, the computer is entering the smallest of businesses. The computer is now even entering the home as a mass market item. The economics of the expansion are simple: as the market expands, the manufacturing costs fall which makes the computer a useful device to a larger and larger market and promotes further software development which in turn fuels the expansion by providing more application software to run on cheaper machines.
Today there is a vast array of different sized computers from small personal computers able to process a million or so instructions per second to giant supercomputers which can process tens of billions of instructions per second. A heuristic hierarchy might be personal computers, workstations, minicomputers, mainframes and supercomputers. In addition, special purpose computers act as control devices for numerous industrial activities such as chemical plants and communication exchanges. In new cars, a microprocessor controls the combustion process.
Because of Moore's Law concerning the increase in the number of electronic components on a chip, each new generation of computer is much more powerful than the last. When a new computer is designed it is designed with an existing microprocessor. After six months to a year, the computer comes to market. To sell the computer the manufacturer makes sure that the computer is backwards compatible which means that it can run all the previous software for previous company machines. For example, 80486 personal computers can run all 80386 software, and likewise the Pentium chip was designed to run both 80486 and 80386 software. After several years the software industry catches up and creates software which explicitly uses the power of the new machine. For example, the new operating systems for the PC clone world are just now taking advantage of the power of the 80386 chip. In the meantime new machines are developed on the next generation of microprocessor. Again there will be a lag of several years before software is developed which fully exploits the capabilities of the new machine.
Advances in computing involve considerably more than ever more powerful von Neumann design computers. An important development is the parallel processor, a computer with many CPUs. While parallel processors are potentially much faster the von Neumann designs in that all processors can be working on the program simultaneously, it is a very difficult programming problem to coordinate all the processors to achieve their potential performance. It should be noted that some programs are inherently sequential and can not take advantage of a parallel processor. There are numerous architectures for parallel processors each best suited for a particular type of job. In my opinion the type which is likely to gain in market share are computers that use thousands of personal-computer type microprocessors. Designs vary in whether each processor shares memory with other processors or whether each processor has its own memory. In designs where each processor has its own memory, performance is increased by connecting all the microprocessors into a network. One successful design where the number of processors is 2 to the nth is a N-hypercube where each processor is connected to n other processors. This means that a message between two processors must travel through no more than n nodes in the network.
Another computing concept is a neural network which approximates the operation of biological neural networks( a very large number of links between the microprocessors). Neural networks excel in pattern recognition, a task for which von Neumann computers are not very efficient. Instead of being programmed, neural networks are trained by adjusting internal weights to match their output to specified targets. Neural networks can be software which runs on a von Neumann computer or specially designed computers.
Originally corporations had standalone computers which were fed input from cards and magnetic tapes. Early evolution was towards more powerful mainframes. The next step were systems of terminals connected to the corporate mainframe. Then came the explosion of personal computers. At first personal computers were standalone units on employees desks. Because these PCs were not linked to the corporate mainframe, employees had a difficult time obtaining corporate data for their work. This difficulty created incentives to link these personal computers into networks.
A rapidly growing type of computer network is a client-server network, which is a network of clients, which are PCs, MAC or workstations used by employees, connected to a server which furnishes clients with such thing as huge disk drives, databases, or connections to a network. Servers can be mainframes, minicomputers, workstations, or powerful PCs. More than one server can supply services to the clients. In creating a client-server network, it is frequently efficient to replace an expensive corporate mainframe with a much less costly, powerful workstation. This is known as (downsizing).
A client-server network has many advantages. If a client machine fails, the network remains operational. Such a network has tremendous computer power at a low cost because powerful workstations are as powerful as older mainframes at 1/10th cost. You can pick and choose hardware, software, and services from various vendors because these networks are open systems. Such systems can easily be expanded or modified to suit individual users and departments. The difficulties of such systems are that they are difficult to maintain, lack support tools, and require retraining the corporate programming staff.