PC programmers use system calls from many different sources, MS-DOS, the ROM BIOS and various APIs (application program interfaces) such as Windows 3.1, NetWare and DESQview. This updated second edition represents one of two volumes published to replace the first edition, the other being "Network Interrupts". They provide programmers with a concise description and other essential information on each system call. In addition, the books are sources of information on potential conflicts between calls from different APIS. This edition has been updated to include DOS 6, Windows 3.1, DR-DOS 7 and other APIS.