Prior to the launch of Microsoft Windows 95, most computer viruses were compact programs written in assembly language. Computer viruses written in Ada, BASIC, C, C++. Delphi, FORTH, Visual BASIC and other programming languages were called HLL (High Level Languages) viruses. Viruses written in high level programming languages were larger than those written in assembly language and tended to function more simply. However, their larger size often made them more complicated to analyze and innocent programs written in the same language as the HLL computer virus were sometimes incorrectly flagged as malicious (a 'false positive').