COMPUTER

Typical Number in Hospital: 20

Cost Bands: 3,4,5

References: 3,6

Many types of computer now exist in hospitals and may include dedicated machines dealing with one job (such as calculating results from the output of a laboratory analyser) to those handling many tasks simultaneously (such as patient records and hospital financial information). The main types of computer may be classified as follows.

1. Mainframe computers. These are large digital computers usually remote from the sites of input and output and are staffed by specialist operators and programmers. They usually handle many jobs simultaneously and often in different languages and are used for financial information (salaries, sales and purchase ledgers, budgets) and for personnel and patient records.

2. Minicomputers. Usually these are in a single cabinet at the site of use and are operated by the people who require the results, although they can often be used by several people at once. Typical applications are calculating and presenting the results of dynamic isotope studies in the nuclear medicine department and for controlling process control apparatus such as the energy usage in a large hospital. Minicomputers often do the jobs which used to be performed on mainframe machines but the smaller jobs are now commonly performed on microcomputers.

3. Microcomputers. The central processor (arithmetic and logic unit) on these machines is contained on a single integrated circuit (microprocessor chip), and the whole computer (including memories, peripheral interface units and disc controllers) may be contained on a single printed circuit board. Some of these are extremely powerful and fast computers but their low cost permits them to be used on a single and often relatively trivial application such as converting the results of a single machine into a more useful form. They have an increasingly important application in the handling of text information (word processors) and at the other end of the scale may be used within medical equipment to control the operation of the equipment and manage the display of results. These are appearing now in the most basic equipment such as infusion pumps and cardiac monitors in which they have a fixed internal program.

4. Calculators. It is not easy to draw a distinction between an electronic calculator and a microcomputer but in general a calculator is not fully programmable in that the range of functions is limited by the internal program and design, whereas a microcomputer is normally taken to mean a device which can be programmed to a variety of tasks and usually can deal with different computer languages if these are fed into it by an external device (keyboard, tape cassette, or disc drive).

5. Analogue computer. High-speed mathematical computation can be performed without converting the signals into a digital code. Instead the mathematical functions (e.g. addition, subtraction, multiplication, differentiation and integration) are performed by a series of operational amplifiers. However, the high working speeds of modern digital computers has almost removed the need for analogue machines even for real-time working such as required for process control and simulators.