โ Scribed by Theodore H. Kehl; Christine Moss; Lawrence Dunkel
No coin nor oath required. For personal study only.
In recent years biomedical research has seen the increasing use of digital logic not only in digital computer systems but in a variety of special purpose laboratory controllers. Integrated circuit technology has added impetus to the laboratory use of digital logic because of its low cost, high speed and the fact that complex functions may be purchased in single packages.
However, all too often a designer of a digital logic device will insert gates and flip-flops wherever it occurs to him; that is, he will logically design from the inputs to the outputs placing logic components in an ad hoc design. Such a.design technique should be strongly discouraged because it requires maintenance personnel and/or other designers to reinvent the original design rationale. (Usually, after a few months, even the original designer cannot retrace his own design rationale.) To overcome this difficulty many designers use state logic.
State logic represents a uniform, rigorous, and minimal solution to a design problem and has been used in the design of digital computers for several years. Its basic concept, the state diagram, derives from automata theory (a case-in-point illustrating the usefulness of basic research). It is possible to prove that the minimum state diagram for a process is the minimum logic required for that process (see Kohavi (1)). While this minimum logic is directly translated into a minimum of electronic components in the final device, it is not a minimum of components but a minimum in complexity which is sought. That is to say, given that the failure rate of TTL gates is .003 %/IO00 hours under severe test conditions (2) and the cost of a TTL gate is less than 10 cents, then most of the cost of a device is in its design and subsequent maintenance. Because state logic represents a rigorous, uniform (and simple) method of designing, both original design and maintenance costs are minimized. It makes little difference if gate count is minimized. However, state logic wilI result in both a minimum gate count and a simple, easy to understand design.
State logic is not widely used in the design of devices for the biomedical research community. This paper will present, in tutorial fashion, an introduction to state logic. Additionally a new technique for implementing state logic will be given.
๐ SIMILAR VOLUMES
A fundamental problem with run-time monitoring of parallel programs is the intrusion introduced by instrumenting the original program. In order to minimize the amount of intrusion in monitoring parallel programs, the logical clock approach (LCA) was proposed. It uses logical clocks to time and contr