CODEWITHSUNDEEP
assemblydosx86-16microprocessors
wasim anabtawi
wasim anabtawi

Reputation: 1

Where is the actual code for interrupt service routine found in?

I know that the ISR is found in the interrupt vector table , But where is the actual code for it found in , Is it in MSDOS.sys or IO.sys?

Upvotes: 0

Views: 285

Answers (1)

pbies
pbies

Reputation: 724

Each interrupt has its own handler. Vector (which is just memory address in hex form 1234:5678) can point to:

  1. BIOS which is read-only
  2. any other .sys or program which has been loaded later after system boot-up
  3. additionaly to 2 - when returning from custom handler it can call the original (previous) handler, what is common practice in MS-DOS

Upvotes: 1

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