Compile-time configuration

One header decides what a reader build contains. Flags off here are absent from the binary, not disabled in it: the fare module compiles to nothing at all in a Fluid gate, and there is no runtime switch that could turn it back on.

The module flags

cardrom_config.h, reader firmware
Flag	Here	Adds	Flash
CARDROM_FARE	off	Fare tables, the section-to-fare lookup, and the value field in the record. Turning it on changes what a record means and needs your own network to agree.	18 KiB
CARDROM_PURSE	off	A stored value area in the EEPROM at 0x0010, its counters, and the deduct and top-up commands. Requires CARDROM_FARE.	26 KiB
CARDROM_HOLDER_AREA	on	READ_FREE and WRITE_FREE, and the 7.6 KB the holder writes.	4 KiB
CARDROM_MERGE	on	MERGE over the contact pads, and the transfer of records between two cards.	7 KiB
CARDROM_MERGE_FOREIGN	on	Taking in a library, tool lending or membership card, which lands in the holder's area.	3 KiB
CARDROM_CLOSED_GATE	off	The door logic for a gate that stands shut and opens on a valid presentation. A Fluid gate is half-open, so this is absent.	11 KiB
CARDROM_INSPECTION	off	The handheld inspection mode, for a network that checks cards aboard. No service here is inspected.	9 KiB
CARDROM_PANEL_FULL	on	All twelve languages in the panel. Off, the build comes with two and falls back.	62 KiB
CARDROM_UNVERIFIED_COUNT	on	Counting a record whose seal cannot be checked, and marking it in the log. Off, such a record is ignored.	1 KiB

CARDROM_FARE and CARDROM_PURSE are part of the standard and pass the conformance suite. They are compiled out of every reader and every personalisation run in the Republic, because travel here takes no fare and Article 69(2) leaves nothing for a purse to hold.

Limits and sizes

Compile-time constants
Constant	Here	Meaning
CARDROM_DEADLINE_MS	300	The transaction deadline. The door task refuses a transaction that missed it.
CARDROM_RECORD_DAYS	90	What EXPIRE cuts at.
CARDROM_MAX_COUNT	9	People one record may cover.
CARDROM_AUTH_RETRIES	3	Failures before the key reference is refused for 200 ms.
CARDROM_FRAME_COIL	264	Largest frame over the coil, bytes.
CARDROM_FRAME_PADS	1032	Largest frame over the contact pads, bytes.
CARDROM_NETWORK_KEYS	8	Foreign network keys a gate holds, for checking seals written elsewhere.
CARDROM_LOG_ENTRIES	4096	Entries a gate keeps before it rolls. Identifiers are dropped from the log within seven days.

Personalisation

A card is personalised once, at the mint, and the same header drives it. PERSO_PURSE_AREA leaves the sixteen reserved bytes at 0x0010 zero here; a fork that compiles the purse in claims them. PERSO_HOLDER_AREA sets the size of the holder's area, 7,782 bytes here, and zero on a card that offers none.

Everything else on the card is fixed by the standard: the ROM block, the record ring, the wear reserve and the commit journal. A personalisation run that changes those produces a card the conformance suite rejects.