You could write window App that will present the DOS program. This can be used for hard to detect pages (have no title). This way you know if you hit F1 then page F1 will occur etc. You can combine this with keyboard keystrokes detection Then rewrite it by your new page (can flicker a bit)Ĭontinue this scanning in some timer. Standard text-mode used in DOS is 80x25 characters so read the specific positions of screen and detect strings that match each page of program. Text mode VideoRAM is at B800:0000h if my memory serves well Each character is represented by 2 BYTEs (one is ASCII and one is color attributes). In DOS there are no access violations so you can do anything.ĭetect the actual screen the program is presenting Then write TSR launcher for your program (terminate and stay program) that will change the text screens for you. After that just leave those as are and edit the rest to what you need to detect which strings will broke the exe. So if the edit is bugged return to original executable and try to edit string one by one. If the program uses those texts in specific ways then some thing can be broken like search for specific character/pattern in string to do some crazy effect etc. The string size must stay the same !!! If program uses any kind of CRC then you have to override the call by nop/jump or change the comparison values to the new CRC If file is encrypted you have to try to decrypt it first. Some executables are packet by PKLITE tools so unpack them. Open it as text/hex and if no program string are present then they are in different file or the file is packed/encrypted. Very good DOS tool is HIEW (hex editor + x86 dissasembler). Under DOS both NC and VC have their own which are enough.

Best dos editor