- Buffer Register Definition: A buffer register is defined as a storage unit for binary words, constructed using flip-flops to store each bit.
- Data Loading: Data is loaded into a buffer register at each clock tick, with outputs matching input bits at each leading clock edge.
- Uncontrolled Outputs: Buffer registers do not control inputs, leading to uncontrolled outputs.
- Controlled Buffer Register: A controlled buffer register uses tri-state switches to control data loading and retrieval.
- Operation Control: In controlled buffer registers, control lines manage when data is stored or read from the register.
Buffer registers are used to store binary words. They are made up of flip-flops, each storing one bit. To store an n-bit word, you need an array of n flip-flops. A 4-bit synchronous buffer register, for example, uses four D flip-flops. The entire data word B1B2B3B4 loads into the register with one clock tick. At each leading clock edge, the flip-flop outputs match their input bits, shown as Q1 = B1, Q2 = B2, Q3 = B3 and Q4 = B4.
Buffer registers lack control over inputs, causing uncontrolled outputs. To fix this, controlled buffer registers are used.
In this design, tri-state switches are used to control the operation of loading and/or retrieval of the data to/from the buffer register. Here one has to pull the 
or 
control line (blue line) low in order to store the data into the register, while 
control line (red line) should be made low to read the data.
