PROM Based Synch Machines

PROM Based Synch Machines - PROM Based Synch Machines...

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PROM Based Synch Machines Password_________________ © Copyright 2009 Daniel Tylavsky
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The brain (controller) of the microprocessor you are building is a synchronous machine. Rather than using combinational logic to realize the functions that drive the flip-flop array, the controller uses a PROM to implement these functions. Recall: Programmable Read-Only Memory (PROM) is a memory storage device which can be read-from but not written-to in situ. PROM Based Synch Machines
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The other block is programmable and allows us to implement any function as a canonical SOP form. S 0 S 1 S 2 D 0 D 1 D 2 D 3 D 4 D 5 D 6 D 7 PROM Based Synch Machines Recall that a PROM is made of two functional blocks: One block is a decoder which implements every possible minterm of the input variables. 2 m 0 m 1 m 2 m 3 m 4 m 5 m 6 m 7
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We can think of the OR gates as selecting the minterms needed to implement the function(s). PROM Based Synch Machines abc c ab c b a c b a c b a m c b a F D + + + + = = = ) 7 , 6 , 5 , 2 , 0 ( ) , , ( 7 S 0 S 1 S 2 D 0 D 1 D 2 D 3 D 4 D 5 D 6 D 7 a b c
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When we program the PROM, we specify the connections associated with each minterm using hex representation. PROM Based Synch Machines H A 9 1001 1010 = S 0 S 1 S 2 D 0 D 1 D 2 D 3 D 4 D 5 D 6 D 7 a b c H 53 0011 0101 = H CD = 1101 1100 H B 5 1011 0101 = H 53 0111 0101 = H 80 0000 1000 = H A 9 1010 1001 = H D 4 0100 1101 =
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We can represent this Programmed PROM as: D7 D6 D5 8 Word D4 X 8 Bits D3 D2 D1 PROM D0 S2 S1 S0 a b c 0 1 0 1 0 0 1 1 Addr Data 0 A9 1 53 2 CD 3 5B 4 53 5 80 6 9A 7 D4 PROM Based Synch Machines S 0 S 1 S 2 D 0 D 1 D 2 D 3 D 4 D 5 D 6 D 7 a b c 1 0 0
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This note was uploaded on 10/21/2010 for the course CSE 120 taught by Professor Matar during the Spring '08 term at ASU.

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PROM Based Synch Machines - PROM Based Synch Machines...

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