BenchChapter 8: Scarcity

B55IDEAL DIODE

The task

Two diodes joined at their cathodes pass whichever input is higher, less 0.6 volts.

Do it without the loss: put out the higher of P0 and P1 on CH3 through the PWM pin P2.

The board

The chip's ports, each with its kind and the parts its signal reaches. Cyan reads, lemon writes. On a narrow screen, scroll the board sideways to see all of it.

Sources: V1 2 V sine at 25 Hz, V2 2.5 V, and V3 3 V square at 10 Hz
Resistors: R1 1 kΩ
Capacitors: C1 1 µF
Probes: CH1, CH2, and CH3

Key idea

MOV B, A keeps the first reading.

Hints

Each hint goes a step further than the one before. Open them one at a time.

Hint 1Show

The second reading minus the first is above 0 only when the second is higher.

Hint 2Show

If it is not, start from 0. Either way, ADD B gives the higher reading.

Solution

Reveal the Full SolutionThe complete program for IDEAL DIODE. Open it only when you want the answer.

The reference program

The game's own solution. It passes every test and scores exactly par on every benchmark.

Put out the higher of two inputs, with no drop.

u1SC-2 standard

IN P0
MOV B, A
IN P1
SUB B
JG W
MOV A, 0
W: ADD B
OUT P2

CYCLES: 1000; at par
ENERGY: 2000; at par
NODES: 1; at par
INSTRUCTIONS: 8; at par