Storage Unit
Explore how data is stored in computer memory by understanding the function of latches such as S-R latch, gated S-R latch, and D latch. Learn how these circuits store individual bits and combine to form storage units like bytes, which are essential components of computer registers.
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How is data stored in memory?
To store one bit of data in memory, we use a circuit, called a latch, that remembers or stores the previous input unless it is reset. We can create such a circuit in many different ways, shown below.
S-R latch
The S-R latch, or a set-reset latch stores one bit of memory, i.e., 0 or 1. It uses two NOR gates that are attached in a way that the output of one feeds back to the input of another. The truth table for an S-R latch is given in Table 1. Q and Q are complementary outputs. When one is 0, the other is 1 and vice versa. Q represents the bit being stored by the ...
| R | S | Q | Q’ |
|---|---|---|---|
| 0 | 0 | Latched | Latched |
| 0 | 1 | 1 | 0 |
| 1 | 0 | 0 | 1 |
| 1 | 1 | Not stable | Not stable |
Table 1. Truth table for an S-R Latch. ...