DOS ain't dead - Announcement: KEEPHOOK

Announcement: KEEPHOOK (Announce)

posted by bretjohn , Rio Rancho, NM, 14.10.2021, 00:55

> A different way may be possible by installing KEEPHOOK and covering the
> same interrupt twice: once before installing the TSR and once after.
> However, I'm not sure how to avoid loops or insure that the order of the
> handlers is correct.

Yeah, that's a problem since you don't really know how the TSR handles the interrupt (preprocessing vs. post-processing vs. both, sometimes passing the interrupt through to previous handler and sometimes not, CALLing vs JMPing, IRQ handlers sometimes issuing the EOI and sometimes not, etc.). It can get really ugly. AMIS, or even just IISP, makes much of that a whole lot easier. Though I've never seen one that did this, a TSR could keep track internally (instead of using the IISP header) of, e.g., whether or not it needs to issue an EOI and changing the order around could mess that up.

> Thanks for the feedback. I may consider adding a diagram. I'd have to draw
> it with ASCII art though.

I was imagining ASCII art rather than a "real picture".

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Complete thread:

Announcement: KEEPHOOK - ecm, 12.10.2021, 18:54 (Announce)
- Announcement: KEEPHOOK - ecm, 13.10.2021, 18:26
- Announcement: KEEPHOOK - bretjohn, 13.10.2021, 21:24
  - Announcement: KEEPHOOK - ecm, 14.10.2021, 00:27
    - Announcement: KEEPHOOK - bretjohn, 14.10.2021, 00:55
      - Announcement: KEEPHOOK - ecm, 16.10.2021, 18:53
- Announcement: KEEPHOOK - andrewbird, 17.10.2021, 18:30