At first every game was copied out of eXoDOS into a bundle next to the code. Fine for SkyRoads, silly for a 456 MB CD game already sitting on the disk.

js-dos accepts a list of zips, so now a game boots from two: a few hundred bytes generated on the spot, then the eXoDOS zip itself, untouched. The generated one has the dosbox.conf and an entry for every folder, because eXoDOS zips have none and js-dos only creates a file's parent folder, not its grandparent. Without that Wolfenstein 3D never started. Everything else comes from the zip's file list and eXoDOS's own launch script: which CD image to mount, with the file name's real case (Guy Spy's cd\GuySpy.cue lives in CD/, and js-dos cares), which drive and folder to start from, whether call run means RUN.BAT or RUN.EXE.

Memory is the limit. A game takes about five times its zip size while it runs. The Last Bounty Hunter's 194 MB ran in 1.1 GB, Space Ace CD's 541 MB in 3 GB. The 1 GB discs don't fit.