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8-Bit Digital Adder

Digital

Eight full-adder cells built from XOR/AND/OR primitives. Changing an operand or carry input dispatches one synchronous logic pass; high nets glow as the carry ripples left to right.

66 components · 89 connections · event-driven Boolean solver

recommended lab 1 of 11

Trace a carry dependency through a combinational gate network.

Prerequisite: none — start here.

predict · then test

Before running 111111112+1211111111_2 + 1_2: which part of the result can settle first?

Commit before the explanation appears. This is a prediction, not a quiz score.

governing model
Si=AiBiCi    Ci+1=AiBi+Ci(AiBi)S_i = A_i \oplus B_i \oplus C_i \;\cdot\; C_{i+1} = A_iB_i + C_i(A_i \oplus B_i)
structural inventory
  • 8×8\times full-adder cell
  • 16×16\times XOR + 16×16\times AND
  • 8×8\times OR carry merge
  • A/B/CinA/B/C_{in} + Sum ports
boundaries
  • 88-bit operands · 00255255
  • sum 00511511 with carry-out
  • per-gate propagation delay
diagnosis challenge Fault identity withheld: infer it from the changed outputs first.
causal signal trace paused

Sample A, B, and CinC_{\mathrm{in}} The input register changes now; no sum output is allowed to jump ahead of the carry front.

step 1 / 10 Sample A, B, and Cᵢₙ

simulation 01 · digital Interactive ripple-carry matrix
logic network online mode=full
8-Bit Digital Adder66 components and 89 connections.CINCinA0A0B0B0X1_0XN1_0AX2_0XN2_0AO1_0OS0S0A1A1B1B1X1_1XN1_1AX2_1XN2_1AO1_1OS1S1A2A2B2B2X1_2XN1_2AX2_2XN2_2AO1_2OS2S2A3A3B3B3X1_3XN1_3AX2_3XN2_3AO1_3OS3S3A4A4B4B4X1_4XN1_4AX2_4XN2_4AO1_4OS4S4A5A5B5B5X1_5XN1_5AX2_5XN2_5AO1_5OS5S5A6A6B6B6X1_6XN1_6AX2_6XN2_6AO1_6OS6S6A7A7B7B7X1_7XN1_7AX2_7XN2_7AO1_7OS7S7COUTCout
8-Bit Digital Adder
direct manipulation enabled Click any A, B, or Cin port in the schematic

control surface

00101011
01010110

live telemetry

Σ decimal 129
binary result 010000001
carry out 0
28 high paths low paths muted propagation nominal