Programmable logic university of california, berkeley. The or array allows any combination of product terms to be included in each sum term. Sequential programmable devices sequential programmable logic device spld includes andor array pal or pla and flipflops complex programmable logic device cpld collection of plds on a single integrated circuit and io blocks. F 0 i 0 i 1 i 15 p 0 p 1 p 47 s 0 s 1 s 7 f 1 f 7 fuse. Fareed yousuf jawwad khatri muhammad afnan smi university 2. Generic array logic was introduced by lattice semiconductor co. The kowalski definition of logic programming is abstracted to. The inputs in true and complementary form drive an and array, which produces implicants, which in turn are ored together to form the outputs. One is called the and plane and the other is called or plane.
Programmable logic devices plds combinatorial circuits. Cmps375 class notes chap03 page 10 26 by kuopao yang. Pla shares single product term across multiple ors array, so highest logic density is available to the user. Plds programmable logic devices pld general purpose chip for implementing circuits can be customized using programmable switches main types of plds pla pal rom cpld fpga custom chips. Other paradigms we might compare it to are imperative programming or functional programming. The fpla had a fixed number of inputs, outputs and product terms that consisted of and and or arrays that contained programmable inputs. Home page jj j i ii ilfp go back full screen close 2 of 280 quit contents 1 lecture 1. It is cheap compared to pla as only the and array is programmable. Programmable logic array pla programmable logic array is a programmable logical device. A militaryaerospace programmable logic users group is being formed.
The idea began from read only memories rom that were just an organized array of gates and has evolved into system on programmable chips sopc that use programmable devices, memories and configurable logic all on one chip. The goal of the organization is, similar to other disciplines, promote sharing of ideas, techniques, information, product announcements, alerts, and experiences between users of the technology, parts and reliability engineers, and vendors. Gal offered cmos electrically erasable prom eprom, e2prom variations on the pal concept. Pals comprise of an and gate array followed by an or gate array as shown by figure 1. It is generally used to implement combinational logic circuits. So he invented a symbolic algebra for logic in the. This applet shows the structure of a pla or programmable logic array. By programming the and section, we generate only those boolean product terms that. Constructive logic frank pfenning lecture october, 2009 1 computation vs. Array logic n a typical programmable logic device may have hundreds to millions of gates interconnected through hundreds to thousands of internal paths. The fieldprogrammable gate array fpga is a generalpurpose semiconductor device containing a large number of digital logic building blocks. Introduction to programmable logic devices 2015 kael hanson. Lecture 32 design using programmable logic devices.
Programmable array logic pal is a type of programmable logic device pld used to realize a particular logical function. Programmable logic devices department of electrical and. The main advantage of the pla structure is that a very compact and spaceefficient realization is possible in nmos technology. Max 3000a programmable logic device family data sheet macrocells max 3000a macrocells can be individually configured for either sequential or combinatorial logic operation. The processor accepts input data from various sensing devices, executes the stored user program, and sends appropriate output commands to control devices. For known combinational functions, programmable logic devices pld are often used.
Arrays and how they occupy computer memory manipulating an array to replace nested decisions using constants with arrays searching an array using parallel arrays. Gal architecture has reprogrammable and array, a fixed or array and reprogrammable output logic. Pdf reversible programmable logic array rpla using. There are three kinds of plds based on the type of array s, which has programmable feature. A typical pla consists of two major sections or planes. In a pla, both the and section and the or section can be programmed. Logically, a pla is a circuit that allows implementing boolean functions in sumofproduct form.
Introduction to programmable logic devices ppd stfc. How to design sequential circuit using pla programmable. Pdf unit 5 course notes on plds ayoush johari academia. A programmable logic array pla is a type of logic device that can be programmed to implement various kinds of combinational logic circuits. A prom comprises a fixed and array and a programmable or array, as illustrated in fig. Plas are built from an and array followed by an or array, as shown in figure 5. The design entry tool for the earlier pal was in the form. It has much in common with the modern algebra of sets, and has diverse application in many. Introduction to programmable logic controllers plcs. A programmable logic array pla maps a set of boolean functions in canonical, twolevel sumofproduct form into a geometrical structure. Programmable logic devices plds are the integrated circuits.
In this paper, a new realization for logic functions, namely reversible programmable logic array rpla, has been proposed. Programmable logic device it is an electronic component used to build reconfigurable digital circuits unlike a logical gates which have fixed function a pld has an undefined function at the time manufacture, before pld can be used in a circuit it must be programmed that is reconfigured. The pla using the prom structure turned out to be the first field programmable logic array fpla. Programmable logic arrays plas implement twolevel combinational logic in sumofproducts sop form. A third set of fuses in the output inverters allows th e output function to be inverted if required. The process of entering the information into these devices is known as programming. Field programmable gate array fpga consists of lookup tables, multiplexers, gates and flipflops. Cmps375 class notes page 10 23 by kuopao yang note that this fulladder is composed of two halfadder figure 3. Deduction logic programming is a particular way to approach programming. Designed so the desired circuit can be entered in relay ladder logic form. Field programmable gate arrays fpga many copies of common building block each block can be configured for.
This chapter shows the evolution of basic array structures like roms into. The pla programmable logic array has programmable connections for both and and or arrays. Boole was a mathematician and logician who developed ways of expressing logical processes using algebraic symbols, thus creating a branch of mathematics known assymbolic logic, or boolean algebra. Spld architectures pal the architecture had a mesh of horizontal and vertical interconnect tracks. Programmable logic devices programmable logic devices plds are the integrated circuits.
How logic programming works logic programming uses facts and rules to represent information. This makes him the father of modern symbolic logic. Programmable array logic n x k fuses n inverters k and gates m or gates n inputs m outputs similar to pla only the connection inputs to ands are programmable easier to program than but not as exible as pla there are feedback connections logic expressions for content information to be stored in pal must be obtained. Gal is similar to pal with output logic macrocells olmcs, which provide more. The rom read only memory or prom programmable read only memory. Programmable array logic pal a a compact form of the internal logic of plds can be referred to as array logic when designing with a pal, the boolean functions must be simplified unlike the pla, a product term cannot be shared among two or more or gates.
Programmable array logic the pal device is a special case of pla which has a programmable and array and a fixed or array. A programmable logic array pla is a kind of programmable logic device used to implement combinational logic circuits. Note for example that for output y, only transistors on rows m2, m5, and m6 are. Example old signetics fpla 82s100 field programmable logic array 82s100 is 16x48x8 fuse programmable. Programming logic and design sixth edition array data. The op section can be programmed according to our design needs. In terms of speedtomarket, design flexibility, and cost, fpgas are hardware used when a traditional softwareprogrammable processor system is not enough, but a customer application specific integrated. The pal architecture consists of two main components.
Note that output f1 is the normal or true output even though a c for. The device has a number of and and or gates which are linked together to give output or further combined with more gates or logic circuits. The typical implementation consists of input buffers for all inputs, the programmable andmatrix followed by the programmable ormatrix, and output buffers. Programmable logic arrays plas prefabricated building block of many andor gates actually nor or nand personalized by making or breaking connections among gates programmable array block diagram for sum of products form. The input lines to the and array are hardwired and the output lines to the or array are programmable. Chapter 6 arrays objectives in this chapter, you will learn about. The pla has a set of programmable and gate planes, which link to a set of programmable or gate planes, which can then be conditionally complemented to produce an output. It has 2 n and gates for n input variables, and for m outputs from pla, there should. Programmable logic array pla the pla combines the characteristics of the prom and the pal by providing both a programmable or array and a programmable and array, i. The pla has a set of programmable and planes and array, which link to a set of programmable or planes or array, which can then be provisionally complemented to produce an output. Media in category programmable array logic the following 21 files are in this category, out of 21 total. In the late 1970s the programmable array logic pal architecture was introduced that increased the use of programmable logic. With the aid of software tools, designers could select which junctions would not be connected by blowing all unwanted fuses. However it is to be noted that here only the and gate array is programmable unlike the or gate array which has a fixed logic.
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