BenchChapter 5: Half duplex

B28TOLERANCE

The task

P0 reads a slow triangle wave as a percent of the 5 volt supply.

Light the LED on P1 while the input is from 2 to 3 volts, and keep it dark outside.

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 2.5 V triangle at 25 Hz and V2 2.5 V
Resistors: R1 330 Ω
LEDs: D1 green
Probes: CH1 and CH2

Key idea

2 and 3 volts read as 40 and 60 percent.

Hints

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

Hint 1Show

Two tests in a row: first rule out readings under 40, then readings over 60.

Hint 2Show

After SUB 40, JL catches the low ones. A further SUB 20 and JG catch the high ones.

Solution

Reveal the Full SolutionThe complete program for TOLERANCE. 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.

The LED lights inside a window from 2 to 3 volts.

u1SC-2 standard

L: IN P0
SUB 40
JL NO
SUB 20
JG NO
MOV A, 1
OUT P1
JMP L
NO: MOV A, 0
OUT P1

CYCLES: 800; at par
ENERGY: 1600; at par
NODES: 1; at par
INSTRUCTIONS: 10; at par