Unidad0 Componentes

Functional Blocks of a Computer: Understanding Flip-Flops

Introduction to Flip-Flops

• The functional blocks of a computer consist of circuits, with flip-flops being fundamental components that store a single bit of data.

• A specific type of flip-flop has an output controlled by an "output enable" signal, allowing the stored value to be available at the output labeled 'Q'.

Output States and Control Signals

• The auxiliary output 'Q with output enable' passes through a tri-state buffer, which determines if the value at 'Q' is connected or disconnected (high impedance state).

• The preset input can force the flip-flop to store a value of 1 unless overridden by a reset signal, which takes priority and sets it to 0.

Data Input and Clock Signal

• To change the stored value in the flip-flop using data inputs, an edge-triggered clock signal is required; changes occur only on rising edges.

• Clock signals are distributed throughout sequential logic circuits but do not continuously update flip-flops without control from an "enable" signal.

Updating Flip-Flop Values

• The process for updating involves setting the clock enable high so that on the next rising edge, the current input is captured into the flip-flop.

• Once updated, even if inputs change or clock signals are removed, the last captured value remains stored within the flip-flop.

Outputs and High Impedance State

• There are two outputs: 'Q', representing internal values, and 'Q with output enable', which can be set to high impedance when not enabled.

• When 'output enable' is low (0), it indicates that no valid connection exists at this output; it's as if physically disconnected.

From Single Flip-Flops to Registers

Limitations of Individual Flip-Flops

• A single flip-flop has limited memory capacity as it can only store one bit. Multiple flip-flops are grouped together in structures called registers.

Register Structure and Functionality

• An example register (Latch type CR zero), may contain multiple flip-flops (e.g., 8 bits would have eight individual D-type flip-flops).

• Each flip-flop shares common control signals like clock enable and output enable while maintaining separate data paths for each bit.

Conclusion on Functional Blocks

Combinational Circuits and Their Functions

Overview of Combinational Circuits

• Combinational circuits do not have memory but are essential components in computers. An example is the full adder, which takes two one-bit inputs and a carry from a previous stage to produce an output value and a carry-out.

• The truth table of the full adder completely describes its operation. For instance, with input 000, the output will always be 00; with input 110, the output will be 10. This behavior is defined by the truth table.

• Once implemented using logic gates, the full adder becomes a functional block that can be integrated into CPUs or other functional blocks within a computer system.

Multiplexers: A Key Component

• Another important combinational component is the multiplexer (MUX). It has multiple inputs (which can be wires or integers of n bits) and uses a single bit selection line to determine which input connects to the output.