Aviation Electronics Technician 1 - Historic Naval Ships Association

implemented by simply combining the proper MSIcircuits.Large Scale Integration (LSI)LSI circuits are large and complex, and generallycontain circuitry equivalent to 100 or more typicallogic gates. LSI circuits are also functional in nature.Typical LSI ICs include memories andmicroprocessors.Very Large Scale Integration (VLSI)VLSI circuits are large, complex circuits thatcontain the equivalent of 1,000 or more logic gates.Early digital computers use a mix of SSI MSI,and LSI circuits. Over the years, the trend has beentoward the greater use of MSI, LSI, and VLSI circuits.Today, most computers are predominately MSI, LSI,and VLSI circuits. The SSI circuits are used only ininterfacing the other three larger and moresophisticated types.DIGITAL CIRCUIT CHARACTERISTICSMany factors influence the choice of logiccircuits used to implement a digital computer. Themost important of these are speed, power dissipation,and the availability of MSI, LSI, and VLSI circuits.Other factors include the cost, noise immunity, andinterface capabilities.The most important choice of a type of logicinvolves speed and power dissipation. Speed refers tothe frequency of operation or propagation delay of thelogic circuits. The higher the speed of operation, thegreater the amount of data that can be processed in agiven time. Therefore, computer designers try toachieve as much speed as possible in their designs.Many high-speed circuits and techniques areavailable. Besides choosing circuits with lowpropagation delay times, circuit reduction techniquesare used to minimize propagation delay throughproper physical layout as well as logic simplification.However, speed is always obtained at the expense ofincreased power dissipation and cost. Invariably, thedesigner faces a speed-power tradeoff, and attemptsto optimize the design for maximum speed withinrealistic power consumption and cost guidelines.Choosing ICs for use in a digital computerinvolves not only choosing a specific logic family, butalso in choosing the correct mix of the various ICtechnologies available. By being flexible in thecircuit choice of mix, a designer can more easilyoptimize the design. This means freely mixingdifferent families of bipolar and MOS, as well asVLSI, LSI, MSI, and SSI circuits.For a detailed look at bipolar and MOS theory, aswell as more information on VLSI, LSI, MSI, and SSIcircuits, refer to Aviation Electronics Technician 2(Intermediate), NAVEDTRA 12334, chapter 2.PROGRAMMING FUNDAMENTALSLearning Objective: Recognize concepts andprocedures used in the construction of acomputer program.Computer programming is the process ofplanning a solution to a problem. You can derive ageneral outline for calculating total resistance of aparallel resistance circuit by using the followingsteps:1. Take the reciprocal of the resistance in ohmsof all resistors in a circuit.2. Calculate the sum of the values from step 1.3. Compute the reciprocal of the value fromstep 2.The process of preparing a program from thisexplanation is not difficult. One basic charcteristicof the computer must be considered-it cannot think.It can only follow certain commands, which must becorrectly expressed and must cover all possibilities.If a program is to be useful, it must be broken downinto specifically defined operations or steps. Theseoperations or steps, along with other data, must becommunicated to the computer in a language that itcan understand.NOTE: The instructions are readsequentially unless otherwise stated.Generally, the steps that a computer follows in theexecution of a program are as follows:1. Locates parameters (constants) and such dataas necessary for problem solving2. Transfers the parameter and data to the pointof manipulation3. Performs the manipulation according tocertain rules of logic8-13