Reading the archive
This site is a rearrangement of soundings, an archive of measurements taken off hardware MIDI sound modules. The archive is written by measurement stage — one directory per command that produced it — because that is the order the work happens in. A reader arrives with an address instead, so the site cuts the same records the other way: one page per address, gathered from every stage that touched it.
Nothing is added in the process. Every figure on every page came out of a file in the archive, and every page says which one.
What a measurement is here
The archive records what one unit did, on one measurement path, on one day. It does not transcribe specifications, and it does not generalise. Three consequences follow, and they shape every page on this site.
An address has no name. 40 11 30 is not labelled "vibrato rate", because that label would come from a document rather than from the instrument. What the site can say is what was measured: that an NRPN was found to land there, that it accepts 00 to 7F, and that a struck note sounded different at the two ends of that range.
An absence is not a negative. An address the archive has nothing for is one no run has reached. The site shows that as not measured, never as zero, blank, or absent from the unit. The distinction matters most where a run stopped early: 40 40 00 answers, and the four addresses after it answer, and then the unit went quiet — so what the archive holds for that block is a record of a run that stopped, not of a block that ends.
A finding belongs to a unit. roland-sc8850-01 is one SC-8850, identified in its own record. Another unit of the same model may differ, and nothing here says otherwise.
The four states
Colour on this site carries exactly four meanings, and no page introduces a fifth.
| State | What it means |
|---|---|
| heard | The parameter reached the signal path: two settings of it sounded different by more than the unit fails to repeat itself by. |
| silent | It was asked under a named stimulus and nothing came back. Read this as a fact about the question as much as about the address. |
| refused | The unit would not take the value, or would not answer the read. |
| not measured | No run has put the question. An absence in the archive, drawn hollow so it cannot be mistaken for a finding. |
An address, field by field
Power-on value — what the address held immediately after a power cycle, before anything but a read request had been sent.
Accepts — what the write probe found. The probe writes a ladder of values rather than all 128 and reads each one back, so "5 of the 15 values written" is the honest form: the unit accepted five of the fifteen it was given. The classification beside it is one of four. Accepts takes the value verbatim. Clamps pulls an out-of-range value to the nearest end. Refuses out of range leaves the address alone. Unchanging means the address never moved at all, which makes a clamp and a refusal indistinguishable from outside.
Neighbours — whether the addresses either side of it are separate addresses. This is measured by giving a whole run different values before reading any of them back, which is the only way to tell a store from a window: a window answers with whatever it was given last, so writing and reading one address at a time makes every window look like a store.
Reached by — which MIDI message was measured to land in this address. A control change, an NRPN and a system-exclusive write can all reach the same byte. That an address stores a message's value says where the value is kept; it does not say that anything uses it.
Resets — what each of the unit's resets put back. The probe writes a mark into every writable address first, so an address a reset leaves alone reads as the mark rather than as its default.
Heard — whether two settings of the address changed the sound. Each verdict names the stimulus it was reached under, because a null is a fact about the note as much as about the parameter: a filter asked with a note that decays in a fifth of a second may be inaudible there and plain under a sustained one.
Blocks that hold nothing
Twelve blocks of the SC-8850 have no storage of their own. An address in one of them is not a place a value is kept: reading or writing it reaches one of two drum setup stores instead, whichever of the two was addressed last.
The catch is that the write points it there and the read follows. Write 7F to such an address, read it straight back, and it answers 7F — so it passes every test for being a store, while what actually happened is that 7F went into a different block and came back out of it. Address it again after touching the other store and the same address answers something else, with nothing having been written to it.
The site marks those blocks wherever they appear. Anything a record says about an address in them describes what is being reached through it.
Stimulus names
Names like struck, struck_vibrato and unpitched are identifiers, not prose, and they are not translated in any language on this site. What each one is — the note, the velocity, how long it was held, what it can see and what it is blind to — is recorded in the archive and shown beside it on the observations page.
The emulator
The emulator is a model of the unit's control surface built from these same measurements and nothing else. Send it a message and it answers the way the archive says the unit answered — including the ways it failed: ask it for 256 bytes and it stops responding until you power-cycle it, because that is what the unit did.
Where the archive has nothing, the emulator says so instead of producing a plausible reply. That restriction is the point of it. A model that filled its gaps in would be a guess about the instrument wearing the archive's authority.