declined by daylight noise

The pull

A card stands in a leaning rail with its stripe against a magnetic head, and there's no motor. You're the capstan. What's on the stripe comes out at the speed of your hand, on three tracks at once, so one pull is three layers. A real stripe holds real data, and data through an audio head is a steady tone for the zeros at each end and a screech of chirps between them, different on every card. Pull slowly and it's a growl with a beat in it.

The wallet you already own is a sample library: a hotel key, a gym pass, a library card. It reads a stripe as sound and nothing else. It never decodes one, and anything it keeps is gone when the power goes off.

Slow: low and dark, because the stripe's shortest wavelengths are too short for the head. Fast: high and bright.

Stop: it stops. Back: it plays backwards. Work it to and fro over the head and it scratches.

Start high: from the top of the card you get the tone of the zeros first. A card can run past the module's foot, so it wants a bottom row.

The terminal

Every pull that leaves the head by the end of the card, at least 60 mm from where it started or last turned, is judged. In the window it's approved, and kept. Outside it, a flat two-tone buzz, and it's thrown away, and what you had stays. Pull it out the way it came and there's no verdict at all.

NEXT: plays the kept pull, and it's the terminal's clock. With a clock here it wants a pull one, two, four or eight periods long, so approved means in time, and a kept pull is then fitted to the clock exactly. With nothing here it wants a shop assistant's 0.6 s. Nothing kept, and every NEXT buzzes.

TERMINAL: how fussy, about the time, the steadiness and how straight the card ran. Fully left, anything goes. Noon, a fair till. Past three o'clock it wants a machine. It judges replays too: never up to noon, one in five at three o'clock, nine in ten at full, and the buzz is a rhythm of its own. Its jack adds to it, 5 V the whole way.

The sign: the top word is what's kept, an eighth of it a letter, each as strong as it isn't worn, and a replay runs down it at the speed of your hand. The bottom word flashes when it says no.

What it keeps

REPLAY: three stops. First, whole: a NEXT plays all of it at one steady speed, your hand's wobble taken out, and NEXTs during it are ignored, so a pull of four bars loops every four. Second, chopped: cut in eight, each NEXT the next eighth. Third, as you pulled it: stumbles, stops and scratches, and HAND with them.

RATE: the kept pull's speed, two octaves each way, noon as pulled. Its jack is 1 V an octave and moves the buzz as well. Your hand does the live pull.

WEAR: every replay wears what it reads, level and top end first, then dropouts that land in the same places each time and spread. Fully left it never does. Noon, about forty plays. Full, six or seven, and then it's gone, and the terminal declines it until you bring another card.

VOID: throws the kept pull away. It's lit for as long as something's kept.

Writing

Hold REC and pull, and what's at IN goes onto the stripe at your hand's speed, a second or two of it. A second write head sits 9 mm above the read head, so on a pull down you hear what you've just written a moment later, off the card. Read it back on another pull and it wobbles twice. A write gets no verdict. It writes over what's there, so use a blank.

TRACK: three stops: which track REC writes, A, B or C. The other two go on reading.

CHARGE: how hard the head's driven, both ways. Reading, the gain, kept pulls too. Writing, the current. Fully left it's barely there, noon is clean, and full is a square: every edge a crunch, on the card for good if you're writing.

A slow write loses the top of IN for good, because its wavelengths are too short for the stripe. A fast one keeps more and holds less.

What comes out

A, B and C: the stripe's three tracks, live and kept together.

HAND: how fast and which way the card's moving, 5 V at 500 mm/s. Replaying as you pulled it, it plays your hand back.

THANKS: a gate on every approval, and every replay that gets through.

SORRY: a gate on every decline.

Specs

Format

Width: 28 HP
Controls: a real card in a rail, 4 knobs, 2 three-way switches, 2 lit buttons

Inputs

IN: audio
NEXT: gate, rising past 1 V
RATE: 1 V an octave
TERMINAL: CV, added to the knob, 5 V the whole way

Outputs

A, B, C: audio, ±5 V
HAND: CV, ±5 V
THANKS, SORRY: gates, 5 V, 10 ms