Compare DOS and BIOS call

Answer 1

BIOS is the basic input output system provides a routine procedure, and use a program written in BIOS features simple, readable, and easy to transplant.

PC-DOS is the most important operating system, as it includes nearly a BIOSdevice management, directory management and file management procedures, is a fully featured, easy to use collection of the interrupt routine. Using the DOS operatingusing the appropriate functions of the BIOS than the operation more simple and lessdependent on some of the hardware.

BIOS functions and DOS functions are called by software interrupts. Need tointerrupt the function number before the call into the AH register, handle the function number into the AL register, besides, usually need to register in the CPU to provide specialized call parameters. In general, DOS or BIOS function calls, has the followingbasic steps:

1, the call parameters into the specified register;

2, for the function number, put it into the AH;

3, for sub-function number, put it into the AL;

4, according to interruption of DOS or BIOS interrupt call;

5, check the return parameters are correct.

BIOS and DOS interrupt interrupt the relationship shown in Figure 9.1.

In the memory system, starting from the address 0FE000H 8K ROM (read-only memory) is equipped with a BIOS (Basic Iuput / output System) routine. Reside in theROM BIOS in the PC series of different microprocessors to provide a compatible system POST, boot loader, the main I / O devices and the interface control processfunction modules to handle all system interrupts. Use BIOS calls that bring great convenience to the programmer programming, programmers do not understand the details of hardware operation, the direct use of instruction set parameters, and thencall the BIOS interrupt the sub-function, so programs written using simple BIOSfunction can be Reading is good, and easy to transplant.

DOS (Disk Operating System) is the most important PC, operating system, which isprovided by the floppy or hard disk. Its two DOS BIOS module IBMBIO.COM andIBMDOS.COM the more convenient to use because more and DOS module providesthe necessary tests, the DOS operating the corresponding functions of the BIOS than the use of more simple operation, but the hardware DOS Dependence less.