First post, by fargo
Microsoft cooperated with a Canadian company in 1987 to release a localized version of MS-DOS 3.30 (Arabic). The operating system supports MDF and CGA cards with Arabic ROM fonts. It can also load fonts into memory for Hercules+, EGA and VGA cards.
An archived copy can be found here: https://archive.org/details/msdos-330-ar . This copy doesn't boot. It displays an error message saying "Security Device failure" as it needs a parallel-port dongle.
I compared the files with a regular DOS 3.30 (English) and found that protection was implemented in IO.SYS file. Replacing the IO.SYS file with one from the regular DOS version allows the localized OS to boot, but breaks the locatiolizaion features such as changing charset and loading fonts.
I tried tracing the IO.SYS execution while booting, using QEMU and GDB, but couldn't figure out how to bypass the dongle protection.