The casino computer virus

Computer virus

A computer virus is a computer program that can replicate itself and spread from one computer to another. The term "virus" is also commonly but erroneously used to refer to other types of malware, including but not limited to adware and spyware programs that do not have the reproductive ability...

 is a malicious

Malware

Malware, short for malicious software, consists of programming that is designed to disrupt or deny operation, gather information that leads to loss of privacy or exploitation, or gain unauthorized access to system resources, or that otherwise exhibits abusive behavior...

 virus that upon running the infected file, copies the FAT to RAM, then deletes the FAT from the hard disk. It challenges you to a game of Jackpot of which you have 5 credits to play with, hence the name. If you fail to win, the computer shuts down, thereby making you have to reinstall MS-DOS

MS-DOS

MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...

. The message it shows when it challenges you reads:
The casino computer virus activates on the 15th of April and may activate on other dates.