The discs

A disc is the one part of this machine a reader puts there. Everything else the page builds — the processor, the memory, the picture — is the machine being itself; a disc is somebody else’s object pushed into a slot, and it leaves the way it came in, changed by whatever ran off it.

<colophon-disc> is the two drawers: drive A, which is the machine’s own, and drive B, which is the connector for a second. It shows what is in each, and it is where a disc goes in, comes out, and is written back to a file.

<colophon-disc></colophon-disc>

What each drawer says

A drawer holds a name, which is the player’s own: an image carries none, so what stands there is the file it was read from. Beside it is the disc’s shape and what has become of it.

The three controls

+ opens the reader’s own file picker and puts what it finds in that drive. ↓ writes the disc out and hands it to the browser to save. × takes it out. The last two are dark while the drawer is empty, because there is nothing there to write or to take.

A disc goes in the moment the picker closes, and the machine keeps running while it does. That is what a drive door is: the operating system finds a disc where a moment ago it found none, and says so on the next thing it is asked.

When a disc is refused

An image is somebody else’s file and is trusted for nothing. The reader proves every offset lies inside it before reading it, and a defect that would make the rest unsafe refuses the whole image rather than handing back half a disc that looks whole.

A refusal is printed under the drawers in the reader’s own words — a sector's data runs past the end of the image, the image does not begin like a disc image — and it leaves that drawer empty. It has to: the bytes the picker just delivered are the very bytes the disc that was in there was reading from, so the old disc cannot survive a new image being laid over it.

A disc named in the element’s own attributes is refused on another road. It is read while the machine is being built, so a bad one stops the building: no machine arrives, no panel begins watching, and the page stands empty with the reason thrown into the browser’s console. That is what a bad snapshot does too.

One sentence there is the player’s own rather than the machine’s. A disc is given a megabyte of room, which is five times what a CPC’s own discs need and enough for the extended images of protected ones; an image past it is refused before a byte of it is written anywhere.

Writing a disc back

↓ writes the disc as it stands now, in the extended layout and always with the sector positions, so an image written here and read again is the same disc to the byte. It is offered whether or not anything was written, because a disc that was only read is still a disc worth keeping.

Two kinds of disc cannot be written out at all, and both say so instead of writing a broken image: one holding a track the format has no way to record, and one needing more room than a megabyte. A drawer with nothing in it says that too.

The disc is not in the record

The drive and the controller rewind with everything else; the medium does not. A rewind therefore puts the head back where it was and leaves the bytes where they are, so a moment before a sector was written can be stood in, and the sector there will already hold what the write put in it. written stays lit once it has lit.

Without a disc interface

The 664 and the 6128 have the interface built in. A 464 does not, and gets one plugged into it — with the AMSDOS ROM it brings — only when the element is given a disc to start with. A machine with no interface says so under its drawers, and a disc put into one does not even turn: the motor line runs from a port only the interface answers at, so nothing can start it.