➕ Somador de 8 Bits

The Input A and Input B panels each show eight bit buttons running from bit 7 down to bit 0; clicking one toggles it between 0 and 1. The Sum panel displays the result in binary, decimal and hex, plus an overflow indicator. The Reset button clears both numbers to zero, and the Random button fills both with random bits.

Adding two 8-bit numbers can produce a value larger than 255, the maximum an 8-bit register holds. The extra ninth bit captures the final carry out of bit 7. Since each operand can reach 255, the largest possible sum is 510, which needs nine bits to represent fully.

The overflow flag shows the carry out of the most significant bit, labelled C₈. When the unsigned sum exceeds 255 it sets to "Yes (C₈=1)", meaning the answer no longer fits in 8 bits. In a real CPU this carry bit is stored in the status register and used for multi-byte arithmetic and comparisons.

Yes, the logic is faithful: it implements true full-adder Boolean equations and a left-to-right carry chain exactly as a hardware ripple-carry adder would. The main simplification is timing; the animation flashes the carry path for clarity rather than reproducing real gate propagation delays measured in nanoseconds.

Because each stage must wait for the carry from the stage below it, the worst-case delay grows linearly with the number of bits, giving O(n) propagation time. For wide words this critical path through the carry chain limits how fast the circuit can be clocked.

Carry-lookahead adders compute carries in parallel from generate and propagate signals, reaching all carries in roughly O(log n) time. Other fast designs include carry-select, carry-save, and parallel-prefix adders such as Kogge-Stone, all of which trade extra logic for shorter delay. Modern processors rely on these instead of plain ripple-carry.

Computers subtract by adding the two's complement of the second operand: invert its bits and add 1. The same adder hardware handles subtraction once the input is negated, which is why a single ripple-carry adder, combined with inverters and a carry-in, can perform both addition and subtraction in an ALU.