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Techniques & Technology

Password Systems

Save without battery

Password systems encoded game progress into alphanumeric strings, allowing players to resume without expensive battery-backed save RAM in their cartridges.

NESSNESsega-mega-drivegame-boy programmingsavetechnique 1984–present

Overview

Write it down. Password systems encoded player progress—level reached, items collected, stats gained—into strings of letters and numbers. No battery backup needed, but players managed notebooks full of codes. Some systems were elegant (Metroid’s 24-character grid), others tedious (long alphanumeric sequences). All served the same purpose: save without hardware cost.

Fast facts

  • Purpose: Save progress without battery RAM.
  • Method: Encode state as string.
  • Cost benefit: Cheaper than battery backup.
  • Player burden: Must record passwords.

How passwords encode data

Data typeEncoding
Level numberCharacter positions
Items collectedBit flags
StatsNumeric encoding
ChecksumValidation

Famous password systems

GameFormat
Metroid24-character grid
Mega ManGrid-based
Kid Icarus24-character
Castlevania IIAlphanumeric

Password length factors

FactorEffect on length
More dataLonger password
Error checkingAdditional characters
Character setLarger set = shorter

Metroid passwords

CodeEffect
JUSTIN BAILEYSuitless Samus
NARPAS SWORDDebug mode
Regular saves24 characters

Design considerations

ChallengeSolution
Transcription errorsChecksums
ExploitsValidation
User-friendlinessReadable characters
LengthBalance data vs convenience

Character set choices

ApproachTrade-off
Alphanumeric onlyLonger, clearer
Case-sensitiveShorter, error-prone
Exclude confusablesO/0, I/1 removed

vs Battery backup

AspectPasswordBattery
CostFreeExpensive
ConvenienceManualAutomatic
ReliabilityAlways worksBattery dies
ShareabilityCan share codesCannot

Player experience

ProCon
No battery failureMust write down
Shareable progressLong sequences
Cheat codes possibleTranscription errors

See also