I have this task to "Design a 32 x 4 memory using two 16 x 4 chips". But on Google I can't find what a 16 x 4 RAM is. I know the basics of latch, flip-flops, TTL, CMOS etc. But I can't put this together. Where do I start?

  • \$\begingroup\$ Memory sizes are usually specified as [number of words] x [number of bits per word], so a 16 x 4 memory would have 16 words of 4 bits each. \$\endgroup\$ Feb 20, 2014 at 19:31
  • \$\begingroup\$ Where is this task from? If it's a homework assignment, surely there's some background provided... \$\endgroup\$ Feb 20, 2014 at 19:43
  • \$\begingroup\$ I have a hard time imagining you'd be able to find an "X by 4" (4-bit word) memory chip nowadays; everything will be either 8+ bits. \$\endgroup\$
    – Nick T
    Oct 5, 2014 at 16:40

1 Answer 1


As this sounds like a homework question I'll give you something to start your answer.

32 x 4 means 32 unique addresses (that is 5 bit address) with a 4 bit data lines. Similarly 16 x 4 would be 16 unique addresses (that is 4 bit address) with 4 bit data lines.

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  • \$\begingroup\$ Actually I don't understand the technology’s , Can you please give a link about the how the IC's work. And this is a exam question but professor didn't teach anything about this. \$\endgroup\$ Feb 21, 2014 at 5:27
  • \$\begingroup\$ The chip MM74C89N matches Jim Dearden's 16x4 pinouts exactly (!MEMORY ENABLE in the datasheet is the same as CE above), except the IC has separate input and output lines. But the datasheet timing diagrams and truth table should give you an idea how the chip works. \$\endgroup\$
    – tcrosley
    Feb 21, 2014 at 15:32

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