checkpoint

not today

20 HP

Every note that arrives is checked against today's rules: let through, it plays; turned back, it's stamped, and the stamps make a rhythm of their own. Each day the ministry adds a rule, until almost no one gets in. Then a new month opens the border.

The CHECKPOINT panel: black, with a border wall at night in gold dots: a watchtower up each edge, wire along the wall under STRICT, a shut gate down the middle and snow at the foot. Under the name, a sheet of bare circuit board ruled into a heading and eight lines; either side of it a stamp mark of bare board; up the gate a column of eight small round windows. PAPERS and NEXT at the top corners, APPROVE and DENY under them, STRICT the big knob in the middle with DAY and MONTH either side, MERCY and SLIP below, THROUGH and DETAINED low down, APPROVED and DENIED in the bottom corners with the DAYS switch and its five dots between them. checkpoint at the top, daylight noise at the bottom.

Turn a knob: drag it or tap either side of it, roll the wheel over it or use the arrow keys; a double click puts it back. DAYS clicks from stop to stop the same ways. APPROVE and DENY are buttons: press one to let the next entrant in or turn him back, or hold it for every one. The patches step on by themselves until you touch anything.

What you hear is a rack played by CHECKPOINT: a melody into PAPERS, an entrant every sixteenth; those let through play the lead, every refusal strikes the stamp, over a kick, a hat and a dark pad. All made in the page as you listen.

example patches

The rules, verdicts, days and lights here are CHECKPOINT's engine as it's designed, running in your browser; the melody, clock, lead, stamp and drums stand in for the rest of a rack.

The border

Each gate at NEXT calls an entrant, and the note at PAPERS is who he is. If he passes every rule in force he's let through, and THROUGH and APPROVED play him. If not, he's turned back: held at DETAINED and stamped at DENIED.

PAPERS: the entrant's note, read a millisecond after NEXT rises and taken to the nearest semitone.
NEXT: every rising edge calls the next entrant; unpatched, every new note at PAPERS is one.
STRICT: how fast the rules pile up. Fully left the border stays open; at noon a rule a day; fully right the whole bulletin from the second day.
STRICT, the jack: a CV added to the knob; 5 V takes it the whole way round.

The bulletin

Day one, everyone enters; the first one through sets the root, and the ministry's scale is the minor scale on it. Then the rules come, in this order:

Only notes of the ministry's scale.
No leap past a fifth from the last one let in.
Off the beat, only the last one let in, again.
Nothing below the line: the month's first note.
Papers must match: only notes of the chord of the last one let in.
Only note names that came through yesterday.
Only the home chord: root, third and fifth.
Only the root.

Late in a strict month the rules can't all be met, and nobody gets in. On the panel a line lights for each rule in force, and the queue shows how much of today is left.

The days

DAYS: how many entrants make a day. Its five stops, left to right, are 4, 8, 16, 32 and 64. Ten days make a month.
DAY: a gate in: a new day now, whatever DAYS says.
MONTH: a gate in: a new month now, the bulletin torn down and the border open. Patched, only it ends a month.

The inspector

MERCY: what's done with one who fails. Fully left he's turned back; turned up, anyone near enough is bent to the nearest note the rules allow and let in: a semitone at noon, everyone fully right.
SLIP: his mistakes. None fully left; one verdict in eight wrong at noon; fully right, half of them. A wrong one slips through as he came, or a right one is stamped.
APPROVE and DENY: by hand. A press lets the next entrant in as he is, or turns him back; held, every one while it's down. A cap is lit while it waits.
MERCY and SLIP, the jacks: CVs added to the knobs, 5 V the whole way.

What comes out

THROUGH: the last one let in, 1 V an octave, held.
APPROVED: a gate with NEXT's for each one let in.
DETAINED: the last one turned back, 1 V an octave: the refused melody, a second voice.
DENIED: the stamp, a trigger on every refusal.

Specs

Format

Width: 20 HP
Controls: 3 knobs (STRICT's big), a five-stop switch, two lit buttons

Inputs

PAPERS: V/OCT, ±5 V
NEXT: gate, rising past 1 V, an entrant each
DAY, MONTH: gates: a new day, a new month
CVs: STRICT, MERCY, SLIP: ±5 V, added to the knobs

Outputs

THROUGH, DETAINED: V/OCT, ±5 V
APPROVED: gate, 0/5 V
DENIED: trigger, 0/5 V, 10 ms