The GATE Grind

GATE 2013 CS (CS1) – Question 56

Digital Logic · Combinational Circuits · 2 marks · Multiple choice

A RAM chip stores 1024 eight-bit words. How many 2-to-4 decoders with enable are needed to build 16K×16 RAM from 1K×8 chips?

  1. 4
  2. 5
  3. 6
  4. 7

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (B) 5

Explanation

Two chips in parallel create a 1K×16 bank, and sixteen banks supply the required depth. Bank selection needs a 4-to-16 decoder, built from one first-stage 2-to-4 decoder enabling four second-stage decoders. Therefore five decoders suffice, B; the ten low address bits go to all chips.

More Combinational Circuits questions

All Combinational Circuits questions →