The catalogue was hidden by placing a VDU21 control code in the last character of the title string. This effectively disables VDU output. In addition the first file name was ![12][3]AVP[21]. The control codes cleared the screen, switched off printer output and disabled the VDU.

Additionally the disk had only the first 20 tracks formatted, thus preventing *BACKUP.

*COPY *.* was prevented by the control codes in the first file.

A new 40T disk was formatted. The file names were read from track 0 sector 0 of the original disk using ADI. Using *COPY 01 B* copied the files beginning with B and this method was used for all the files on the original disk. !BOOT was also copied using *COPY 01 !BOOT. The boot option was set to RUN using *OPT 4 2 and the disc worked and could be archived.


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