Compare DOS and BIOS call?
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.