MS DOS and the BIOS
•Basic Input/Output System
–Firmware in ROM
–HW initialize and test
–Hardware control routines
–Establish a low-level API
–Bootstrap
•MS DOS
–Written for IBM (PC-DOS)
–Establishes a higher-level
API for application programs
     MS DOS
              BIOS
   Hardware ( Disk drive ,printer
Keyboard, motherboard)
Figure 21.1