How to Run ThinkTank (2.0) from a Harddisk without Program Modifications If you wish to run "ThinkTank" (2.0) from a hard disk, but are annoyed by the requirement for having the original disk 1 in drive A, then read on.... Part of this ARC file is the program "THINKFIX.COM". All you have to do is to include this program in your "autoexec" file when running ThinkTank. For instance, your "autoexec.bat" might look like this: DATE TIME THINKFIX TANK That's all there is to it. ThinkTank will no longer look for the key disk in drive A. The protection logic for ThinkTank is quite simple. On side 1, track 27 (hex), sector 01 (hex) of the original disk 1 is a string of 128 bytes of hex D6. The program looks for this string and, if it can't be found, you are returned to DOS. THINKFIX is a resident interrupt handler (or "demon") which screens disk I/O calls. When a call occurs to the special sector mentioned above, THINKFIX sends back the required string to ThinkTank. (Calls to any other sector are processed normally by the BIOS INT 13h code). Voila, ThinkTank thinks it has successfully read the original disk 1 and processing continues normally!