There are several methods for hiding the catalogue from the casual observer. These may be used in isolation or combined for a greater effect.
- One or more characters in the disc title are control codes. The usual one is to place Ctrl-U (ASCII code 21) at the start or end of the disc title.
- One or more dummy files containing ACSII code 21 in their file name(s). Such a file at the start and at the end of the files in the catalogue is commonly used.
As a protection method on its own this is rarely found but is quite common when used with unformatted tracks. A disk sector editor can be used to examine sector 0 of track 0. This will show what codes have been used to hide the programs and whether the top bit of characters is set.
Selective use of *COPY can assemble a working disk on a new, formatted disk and the hidden catalogue will be removed.
If the top bit is set in file names, the command *INFO can be used to find the load address, length and execution address of the file. The file can be *LOADed and then *SAVEd with its original load and execution addresses and length.