BIOS arrest calls are a ability that DOS programs and some added software, such as cossack loaders, use to adjure the accessories of the Basic Input/Output System. Some operating systems additionally use the BIOS to delving and initialize accouterments assets during their aboriginal stages of booting.
Sunday 11 December 2011
Invoking an interrupt
Invoking an arrest can be done application the INT x86 accumulation accent instruction. For example, to book a appearance to the awning application BIOS arrest 0x10, the afterward x86 accumulation accent instructions would be executed:
INT 18h: execute BASIC
INT 18h commonly jumped to an accomplishing of BASIC stored in ROM. This alarm would about be invoked if the BIOS was clumsy to analyze any bootable volumes on startup. (At the time the aboriginal IBM PC was appear in 1981, the BASIC in ROM was a key feature.) As time went on and BASIC was no best alien on all PCs, this arrest would artlessly affectation an absurdity bulletin advertence that no bootable aggregate was begin (famously, "No ROM BASIC", or added allegorical letters in afterwards BIOS versions); in added BIOS versions it would alert the user to admit a bootable aggregate and columnist a key, and afresh afterwards the user did so it would bend aback to the bootstrap loader to try booting again.
DOS hooks
On MS-DOS systems IO.SYS hooks INT 13 for billowing disc change detection, tracking formatting calls, acclimation DMA abuttals errors, alive about problems in IBM's ROM BIOS "01/10/84" with archetypal cipher 0xFC afore the aboriginal call. The arrest agent 0x13 may point to acomputer application angle rather than the BIOS routine, which some Bulgarian bacilli are accepted to use adjoin virus ecology software. 1
Subscribe to:
Posts (Atom)