The role of digital components in photogrammetric instrumentations

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Monograph

Persistent identifier:: 830281363

Title:: The role of digital components in photogrammetric instrumentations

Sub title:: symposium of Torino, Italy ; 2nd - 4th October 1974

Scope:: ca. 200 Seiten in getrennter Zählung

Year of publication:: 1974

Place of publication:: Torino, Italy

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 830281363

Illustration:: Illustrationen, Diagramme

Signature of the source:: T 15 B 1280

Language:: English

Additional Notes:: Literaturangaben

Other Title:: Nebentitel: Digital components in photogrammetric devices

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Corporations:: International Society for Photogrammetry, Commission, 2

Adapter:: International Society for Photogrammetry, Commission, 2

Founder of work:: International Society for Photogrammetry, Commission, 2

Other corporate:: International Society for Photogrammetry, Commission, 2

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2015

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: TRENDS IN DESIGN OF DIGITAL EQUIPMENT FOR PHOTOGRAMMETRIC INSTRUMENTS. U. V. Helava

Document type:: Monograph

Structure type:: Chapter

5 is needed to implement sequential logic. A RAM module can fulfill this function, and also act as a PROM or ROM, if needed. PLA (Programmable Logic Array) [8] The programmable logic array may be regarded as a combination of two ROM's or a ROM in which the addresses are also programmable. In any case the PLA approach offers substantial advantages over the ROM. Spe cifically, it is feasible for a PLA to examine a great deal of input information in parallel, without having specific results for all possi ble combinations. In other words, the PLA can have "don't care" input conditions. Similarly, the PLA can present the same output from two different input combinations, and also outputs from a single input con dition. Furthermore, some PLA modules include flip-flop banks for logic feedback within the module. This increases the flexibility of the PLA even further. Microprocessor [9] A microprocessor may be defined as a complete central processor unit (CPU) of a digital computer implemented on one or on a few inte grated circuit (IC) chips. The appearance of microprocessors has caused a great deal of soul searching among designers of digital systems. The reason is that the microprocessor can be used both to put together com puters (often called microcomputers and involving CPU, ROM, and RAM, as well as some other components), and also to perform random logic. In the latter capacity the microprocessor may be considered as a universal logic module. Because of its universality, it can be manufactured in large quantities to keep its price down. This is a great advantage. Its disadvantages are, at least for the time being, that it performs the logic functions relatively slowly, and that its users must learn a new way of doing things: implementation of logic by micro-programming. TRENDS IN SYSTEM DESIGN Designers of digital systems are facing significant transitions in their mode of operation, just as are the detail designers who are be coming de facto system designers. The list of skills and tools needed by such a designer or applications engineer has grown to formidable pro portions. He must thoroughly understand the organization, operation, and performance capabilities as well as limitations of at least one, but preferably several microprocessors, RAMs, ROMs, PROMs, and PLAs; control of input and output; analog-to-digital and digital-to-analog converters; and operation of priority-interrupt systems, peripheral equipment, encoders, servos, control panel circuits, multiplexers, de coders, displays, and numerous logic families. In addition, he must now understand and have extensive knowledge of microprogramming, as well as machine language, and higher level software. On top of all that he must, of course, comprehend the requirements of the application, e.g., photo- grammetric equipment.

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