![]() | This text/reference provides students and practicing engineers with an introduction to the classical methods of designing electrical circuits, but incorporates modern logic design techniques used in the latest microprocessors, microcontrollers, microcomputers, and various LSI components. The book provides a review of the classical methods e.g., the basic concepts of Boolean algebra, combinational logic and sequential logic procedures, before engaging in the practical design approach and the use of computer-aided tools. The book is enriched with numerous examples (and their solutions), over 500 illustrations, and includes a CD-ROM with simulations, additional figures, and third party software to illustrate the concepts discussed in the book. |
Section 6.7 - Configurable PAL Devices
Development in the design of programmable array logic devices led to the introduction of configurable outputs enhancing the output capabilities of such devices. The configurable device architecture is achieved by providing some special circuitary at the output stage, known as macrocells. Each of the macrocells are provided with two fuses that can be programmed for four different configurations of outputs. The output configuration may be of true output without flip-flop or complemented output without flip-flop or true output with flip-flop or complemented output with flip-flop. So it may be observed that this type of device can function for sequential logic circuits as well as for combinational logic circuits and in each case outputs are available in inverted form or noninverted form.

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