SignalChapter 10: Meshes

76SIDE WIRE

The task

X runs from 0 to 7. Below 4, P must receive X cubed; from 4 up, 100 minus X squared.

c and s are SC-2Ls: 2 cycles an instruction, at half the energy.

h and j are SC-1s: register A only, 8 lines.

The board

The board as the puzzle screen lays it out. Cyan pins read, lemon pins write, violet pins go both ways. On a narrow screen, scroll the board sideways to see all of it.

Key idea

A decision travels on a wire of its own: the dealer tells the collector which lane each value took.

Hints

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

Hint 1Show

The middle wire lets h tell j which lane each value took, so j knows where to read.

Hint 2Show

h can send X minus 4: its sign picks the lane, and each lane adds the 4 back.

Hint 3Show

Send the value to its lane before you tell j, so the lane can start while j still waits.

Solution

Reveal the Full SolutionThe complete program for SIDE WIRE. 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.

hSC-1 lite

S: IN P0
SUB 4
JL K
OUT P3
OUT P2
JMP S
K: OUT P1
OUT P2

cSC-2L low power

IN P0
ADD 4
MOV B, A
MUL A
MUL B
OUT P1

sSC-2L low power

IN P0
ADD 4
MUL A
NEG
ADD 100
OUT P1

jSC-1 lite

S: IN P1
JL K
IN P2
OUT P3
JMP S
K: IN P0
OUT P3

CYCLES: 446; at par
ENERGY: 1881; at par
NODES: 4; at par
INSTRUCTIONS: 27; at par

Another way: One lane

A second program that also passes. It beats par on ENERGY, NODES, and INSTRUCTIONS and gives some back on CYCLES.

C does both jobs itself and the middle wire stays idle: one core fewer, far fewer lines and less energy, but one slow lane does all the work.

hSC-1 lite

IN P0
OUT P1

cSC-2L low power

IN P0
SUB 4
JL K
ADD 4
MUL A
NEG
ADD 100
JMP O
K: ADD 4
MOV B, A
MUL A
MUL B
O: OUT P1

jSC-1 lite

IN P0
OUT P3

CYCLES: 713; over par
ENERGY: 1468; under par
NODES: 3; under par
INSTRUCTIONS: 17; under par