Hi everybody,

Could you please help me with the following things,

A 4-bit register uses 4 flip-flops. (each flip-flop stores a bit).
SRAM uses 6 transistors to store a bit, whereas DRAM uses 1 transistor and 1 capacitor to store a bit. My question is why SRAM and DRAM do not use flip-flop to store a bit?

(I am sorry for my English, and I am not a native speaker, and also I am a newbie)

Regards
Feli

 

A flip flop needs much more components to be made. It needs approximately 14 flip flops, so it's a matter of economy.
I 'll try to be more specific on the number and find a schematic too.

 

Hi everybody,

Could you please help me with the following things,

A 4-bit register uses 4 flip-flops. (each flip-flop stores a bit).
SRAM uses 6 transistors to store a bit, whereas DRAM uses 1 transistor and 1 capacitor to store a bit. My question is why SRAM and DRAM do not use flip-flop to store a bit?

(I am sorry for my English, and I am not a native speaker, and also I am a newbie)

Regards
Feli

Actually, an SRAM does use flip-flops constructed of 4 transistors. The other two are used for reading/writing data. If it didn't use flip-flops...it wouldn't be static.

 

You could call it a flip flop, but the construction of a standard flip flop is much different than a 6t SRAM.

 

You could call it a flip flop, but the construction of a standard flip flop is much different than a 6t SRAM.

Ahhh...but there are many ways a flip-flop can be constructed...relays, DTL, vacuum tubes, transistors...just because the circuit doesn't look like a typical flip-flop, doesn't mean it isn't one. To be technically precise, these should all be called "bistable multi-vibrators". The term "flip-flop", according to wikipedia, wasn't even well defined, historically:

• 1942 – multivibrator implies astable: "The multivibrator circuit (Fig. 7-6) is somewhat similar to the flip-flop circuit, but the coupling from the anode of one valve to the grid of the other is by a condenser only, so that the coupling is not maintained in the steady state."[8]
• 1942 – multivibrator as a particular flip-flop circuit: "Such circuits were known as 'trigger' or 'flip-flop' circuits and were of very great importance. The earliest and best known of these circuits was the multivibrator."[9]
• 1943 – flip-flop as one-shot pulse generator: "It should be noted that an essential difference between the two-valve flip-flop and the multivibrator is that the flip-flop has one of the valves biased to cutoff."[10]
• 1949 – monostable as flip-flop: "Monostable multivibrators have also been called 'flip-flops'."[11]
• 1949 – monostable as flip-flop: "... a flip-flop is a monostable multivibrator and the ordinary multivibrator is an astable multivibrator."[12]

I submit for the jury that a SRAM cell is, indeed, a flip-flop.

 

BTW, I can (and I have) build a practical SR flip-flop with two cmos inverters and two resistors.

 

Well, ok. It is a flip flop since it can have only two states. What I wanted to point is that it's not your classic 7474 flip flop.