I recently came across this question: "'Flip-flops are building blocks of memory'. Comment". What should I write as answer to this question? How flip-flops are useful or their structure and stuff? Thanks!

 

It's not really a very helpful question. I think what you would be best doing is to find an answer paper and see what the exam board are looking for, how they want you to answer it and then should you be given any more open ended questions in the future you will be well prepared to answer it in the style that the exam board are looking for.

 

I think this is aimed at the history of computing. Back in the day when Apple was producing the Apple II with the 6502, memory was built with flip flops. I'm sure you can find out more.

 

'Flip-flops are building blocks of memory'

True.

But note that the statement is NOT

'Flip-flops are THE building blocks of memory'

Which would be false.

Even those that would argue for a very loose definition of a "flip-flop" would be pressed to describe dynamic RAM structures as flip-flops, but even there I can envision the argument (I just wouldn't buy it).

 

...Even those that would argue for a very loose definition of a "flip-flop" would be pressed to describe dynamic RAM structures as flip-flops, but even there I can envision the argument (I just wouldn't buy it).

May I try?

A SRAM f-f uses continuous-time feedback to enforce two stable states.
A DRAM f-f uses discrete-time feedback to enforce two (or more!) stable states.

 

That's not bad and it's basically the argument I envisioned (though actually stated more persuasively than I would have put it). Not sure I'm willing to completely buy it, though.

But it comes down to semantics (which are important) and what concept we want people to walk away with when they think of a "flip flop". Do we want it to be a pretty narrowly defined, concrete notion that matches 95% of how they will use it and see it used, or do we want to dilute its concreteness in order to expand the definition to over the remaining 5% that they may well never encounter? I think valid arguments can be made for either way. I tend to favor the narrower approach but being willing to explicitly expand the definition in contexts where it really makes sense to do so.

 

Would it be impertinent to mention that there are other types of memory that preceeded semiconductor memories that are not based on flip-flops? Hmmmm -- I thought so.

 

Would it be impertinent to mention that there are other types of memory that preceeded semiconductor memories that are not based on flip-flops? Hmmmm -- I thought so.

Do you mean core memory?