BenchChapter 4: Stars and hubs

B20CLIPPER

The task

Z1 is a zener diode. It holds CH1 at 3.3 volts at most and lets lower levels pass.

P1 ticks every 40 cycles. On each tick, step the duty on P0 up a quarter:

25, 50, 75, then 100 percent, and back to 25. The top steps come out flat.

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.

Resistors: R1 1 kΩ
Capacitors: C1 1 µF
Zener diodes: Z1, a zener diode
Probes: CH1

Key idea

Without Z1, 75 and 100 percent would give 3.75 and 5 volts.

Hints

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

Hint 1Show

Above 3.3 volts Z1 conducts and takes the extra current from R1.

Hint 2Show

Four blocks of three lines: IN P1, MOV A with the duty, OUT P0.

Solution

Reveal the Full SolutionThe complete program for CLIPPER. 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.

A staircase whose top steps the zener flattens.

u1SC-2 standard

IN P1
MOV A, 25
OUT P0
IN P1
MOV A, 50
OUT P0
IN P1
MOV A, 75
OUT P0
IN P1
MOV A, 100
OUT P0

CYCLES: 34; at par
ENERGY: 68; at par
NODES: 1; at par
INSTRUCTIONS: 12; at par