With the increasing popularity of the Windows environment, advent of 32-bit CPUs, a shift in the PC market and increasing popularity of the Internet came the need for a completely different antivirus approach as well. Besides the virus scanning and cleaning functionality it only featured heuristic analysis. Due to the limitations of the OS (lack of multitasking among others) it didn't feature any on-demand/on-access protection nor most of the other features of the current versions. It was created in 1987 by Miroslav Trnka and Peter Paško at the time when computer viruses started to become increasingly prevalent on PCs running DOS. The first version of NOD32 - called NOD-ICE - was a DOS-based program. The acronym NOD stands for Nemocnica na Okraji Disku ('Hospital at the end of the disk'), a pun related to the Czechoslovak medical drama series Nemocnice na kraji města ( Hospital at the End of the City). 2.3 NOD32 for Mac OS X and Linux Desktop.2.1 File Security for Microsoft Windows Server.1.2 Mail Security for Microsoft Exchange Server.