Wednesday, 29 February 2012

PROM


In PROM only OR array is programmable, AND array is fixed. PROM consists of decoder followed by OR array. Decoder produces all minterms. n-input PROM consists of nx2n decoder. Each OR gate consists of 2n inputs. Thus output is function of n-variables.
To implement m functions of n-variables requires a 2nxm size PROM.
Each of 2n outputs is connected to inputs of OR gates through fuses. The required min term fuses can be left as it is and remaining fuses are blown by applying high voltages. This process is referred as programming.
Boolean function implementation with PROM:
Implement Boolean function f (A, B, C) = ∑ (0, 3, 4, 6, 7)
Since the function is of 3 variables it requires 23x1 PROM 

Back                                         Contents                                   Next

No comments:

Post a Comment