Registers
One handy thing about flip-flops is that we can pack them onto chips pretty tightly. When we put 8 flops onto one chip, we have what's called a register. An 8-flop register can hold one byte of digital information.
Registers are very similar to normal D-flops, with a few differences. Here's a schematic diagram for a D-register:
Naturally, the D0 input feeds the Q0 output, and so on. You'll notice that all 8 of the D-flops are driven by a single clock input, marked with the triangle. They also share a single Reset pin. Registers make it handy to work with whole bytes at a time.
Often, we'll feed a register with inputs from a Data Bus. We'll talk more about the idea of the Data Bus later, but for now, we'll see that we don't have to draw 8 seperate lines when we're feeding a byte into a register. Here's a convient schematic for an 8-bit bus:
The convention is that D0 will represent the lowest order (smallest) data bit, while D7 will represent the highest order (largest) bit.
Here's the pinout for an 74HCT273 register:
