ROM files would ordinarily go here; they are copyright Apple so are not included.

Expected files:

apple2o.rom — an image at least 12kb big, in which the final 12kb is the original Apple II's ROM.
apple2.rom — an image at least 12kb big, in which the final 12kb is the Apple II+'s ROM.
apple2e.rom — a file at least 15.75kb big, in which the final 12kb is the main portion of the Enhanced IIe ROM, that is visible from $D000, and the 3.75kb before that is the portion that can be paged in from $C100.
apple2eu.rom — as per apple2e.rom, but for the Unenhanced Apple II.

apple2-character.rom — a 2kb image of the Apple IIe's character ROM.
apple2eu-character.rom — a 4kb image of the Unenhanced IIe's character ROM.
apple2e-character.rom — a 4kb image of the Enhanced IIe's character ROM.

Apologies for the wackiness around "at least xkb big", it's to allow for use of files such as those on ftp.apple.asimov.net, which tend to be a bunch of other things, then the system ROM.