INT 16 U - PCIBM PC Tools v8+ VSAFE, VWATCH - GET/SET OPTIONS AX = FA02h DX = 5945h BL = new parameter flags (see #00616) Return: CF clear DI = 4559h CL = old value of parameter flags Bitfields for VSAFE/VWATCH parameter flags: Bit(s) Description (Table 00616) 7 Protect executable files 6 Protect FD boot sector 5 Protect HD boot sector 4 BootTo start up the computer or operating system. The term "boot" is a contraction of "bootstrap", which in turn comes from the expression "to lift oneself by one's boot straps." The ROM BIOS on IBMInternational Busiuness Machines PCs and compatibles reads in the first sector of the disk, which contains a short (less than 500 bytes) program that reads in a portion of the operating system, which in turn reads in the remainder of the operating system. See also IPL. sector viruses 3 Check executable files 2 General write protect 1 Resident 0 HD Low level format