Card e-Reader

The e-Reader is a Game Boy Advance cartridge with a scanner in it. Nintendo printed dotcodes along the edges of trading cards — whole little games, Animal Crossing NES titles, extra levels for Super Mario Advance 4 — and you swiped the card through the slot to load one.

In RetroXR you do exactly that, as of v0.6.0. Push the reader into the handheld, then take a card and slide it through the slit, dotcode edge first. There is no bay and nothing to seat: the card is never held, because a card that could be seated would be captured half way through a swipe.

Three readers, and they are not interchangeable

RetroXR carries all three revisions — Card e-Reader (Japan), Card e-Reader+ (Japan) and e-Reader (USA). A reader is its dump, and cards are region-locked: a Japanese reader answers an American card with its own Region Error screen, exactly as the hardware did. Spawn the one that matches your cards.

The reader’s program comes from your library

The e-Reader’s cartridge dump is an ordinary GBA ROM, so RetroXR does not treat it as firmware or ask you to install a second copy under a name of its choosing. Put it where you would keep it anyway:

• roms/game_boy_advance/ — the shelf it belongs on, or
• roms/ereader/ — beside the cards it reads, which is also reasonable.

It is recognised by the ROM’s own header — the GBA game code — not by its filename, so renaming your dump does not hide it. The library then stops offering that file as a game, since it is hardware rather than something you play.

Card names must follow No-Intro

This is the one thing that will bite you. A card is one or two .raw dotcode strips, and RetroXR groups the strips of a card by filename, using the No-Intro naming. Get the names wrong and every two-strip card is silently split into two half-cards.

Both No-Intro conventions are understood:

<card> (Strip 1).raw     +  <card> (Strip 2).raw       two long strips
<card> (Long Strip).raw  +  <card> (Short Strip).raw   a long and a short
<card>.raw                                             a single strip

Why the name matters and the file cannot tell us

Which edge a strip is printed on is not recorded anywhere — not in the dotcode itself (a card’s per-block headers are byte-identical between its strips), not in the core, and not reliably in a scan. Only the strip’s size is certain: 2912 bytes is a long strip and 1872 a short one.

So the pairing has to come from the name. A card whose two strips are not recognised as a pair presents the wrong edge, and swiping it reads nothing.

Cards go in roms/ereader/. A .gba dump sitting in that folder is ignored by the card grouping, which only ever looks at .raw — so keeping the reader beside its cards is safe.

Which edge you present

Every e-Reader card is the same portrait trading card, so there is no card shape to work out — only which of its edges carry a dotcode. A long strip goes on a long (side) edge and a short strip on a short (bottom) edge, because a 2912-byte dotcode does not fit across 63 mm of card.

Present an uncoded edge and nothing is read, which is what should happen — that is a card offered the wrong way round, not a failure.

Scanning, and what a good scan looks like

The scanner has to be powered and waiting for a card. In practice: start the e-Reader software, choose its scan option, and swipe once it is asking for a card. A card offered to an unpowered scanner is simply dropped.

A two-strip card is swiped twice — one strip, then the other — and the software tells you when it is satisfied:

Scanning of Dot Code(s) complete.

"Already Scanned" means the strips were paired wrongly

If a correctly-swiped second strip comes back as Already Scanned, that is the pairing being wrong rather than a read error. Check the two filenames against the No-Intro forms above.

One power-up is one card

The card leaves the scanner when it powers down. A scan session is short — power up, a few sweeps, give up, power down — so swipe within that window rather than lining a card up in advance.