Chapter  IMPLEMENTATION OF COMBINATIONAL LOGIC BY STANDARD ICs and PROGRAMMABLE ROM MEMORIES  ChLDigital Principles and Design Raj Kamal Pearson Education   Lesson  Programmed Read Only Memory PROM
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Chapter IMPLEMENTATION OF COMBINATIONAL LOGIC BY STANDARD ICs and PROGRAMMABLE ROM MEMORIES ChLDigital Principles and Design Raj Kamal Pearson Education Lesson Programmed Read Only Memory PROM

Output bits for the multiple Boolean functions are at data output pins Number of Boolean literal variables Number of address bits in the input Number of Boolean functions Implemented Number of output databits brPage 6br Ch12L3Digital Principles an

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Chapter IMPLEMENTATION OF COMBINATIONAL LOGIC BY STANDARD ICs and PROGRAMMABLE ROM MEMORIES ChLDigital Principles and Design Raj Kamal Pearson Education Lesson Programmed Read Only Memory PROM




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Presentation on theme: "Chapter IMPLEMENTATION OF COMBINATIONAL LOGIC BY STANDARD ICs and PROGRAMMABLE ROM MEMORIES ChLDigital Principles and Design Raj Kamal Pearson Education Lesson Programmed Read Only Memory PROM"— Presentation transcript:


Page 1
Chapter 12 IMPLEMENTATION OF COMBINATIONAL LOGIC BY STANDARD ICs and PROGRAMMABLE ROM MEMORIES
Page 2
Ch12L3-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 2 Lesson 3 Programmed Read Only Memory (PROM)
Page 3
Ch12L3-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 3 Outline PROM Example 3 2 PROM
Page 4
Ch12L3-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 4 PROM Programmable read only memory It stores the output(s) of combinational circuit(s) for different input conditions given in

truth table rows for the circuit
Page 5
Ch12L3-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 5 Input Address and Output Data Bits When a PROM used for the implementation of the combinational circuits, the Boolean variables are the inputs at the address input pins. Output bits for the multiple Boolean functions are at data output pins Number of Boolean literal variables = Number of address bits in the input Number of Boolean functions Implemented = Number of output data-bits
Page 6
Ch12L3-"Digital Principles and Design", Raj Kamal, Pearson Education,

2006 6 PROM PROM is a previously programmed by fused OR links in AND-OR arrays based logic device The Boolean variables are the input to the PROM Output is as per present and fused links to the OR gates
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Ch12L3-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 7 PROM Block Diagram n1 n1 AND gates m0 m1 OR gate links Fused and not-fused
Page 8
Ch12L3-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 8 Outline PROM Example 3 2 PROM
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Ch12L3-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 9 3 2

PROM AND-OR Array with Fusible OR Links D0 D1 m0 m7 Column of 6-input ANDs Two number 8-input ORs
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Ch12L3-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 10 AND INPUTS in 3 2 PROM Six inputs: Three variables A1, A2, A3 and their complements Each AND connects to the inputs such that 8 number AND generate 8 outputs for miniterms m0, M1, m2, ..., m7.
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Ch12L3-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 11 OR INPUTS in 3 2 PROM Two ORs Each OR has 8 inputs from 8 fusible links Each fusible link connects to

one AND output line m0 or m1 or .. m7
Page 12
Ch12L3-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 12 OR INPUT FUSIBLE LINKS in 3 2 PROM If a miniterm is present in a Boolean function, the output of which appears at D0 or D1, then link is not fused and is present If miniterm is not present then the link is fused.
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Ch12L3-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 13 Summary
Page 14
Ch12L3-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 14 PROM is a programmable combination circuit from

AND-OR arrays in which OR gate input links are programmed There are 2 = 8 ANDs to implement 8 miniterms for 2 Boolean functions in 3 PROM
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Ch12L3-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 15 8 outputs of the 3 PROM ANDs are given to two OR gates to obtain two outputs = 2 outputs, D and D . Total 16 fusible links exist with 8 fuses per OR gate in 3 PROM Fusing the links generates the outputs as per Boolean expression and its truth table.
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Ch12L3-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 16 End of Lesson 2

Programmed Read Only Memory (PROM)
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Ch12L3-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 17 THANK YOU