DOS ain't dead

Confusing DEBUG (Miscellaneous)

posted by Japheth , Germany (South), 19.08.2010, 00:52

> On return, the G command of DEBUG just looks whether the current CS:(E)IP
> fits, i.e. points behind one of the breakpoints it set.

I don't think this is the correct description of what - at least - FD Debug does. It's more complicated. After G returned, it does:

- read the byte at CS:E/IP-1
- restore its BPs
- if the byte it has read is 0CCh AND entry into Debug was through interrupt 3, then it again reads the byte at CS:E/IP-1. If its value is NO LONGER 0CCh, then Debug assumes one of its BPs were hit and decrements E/IP.

---
MS-DOS forever!

Complete thread:

• Confusing DEBUG - ecm, 16.08.2010, 04:11 (Miscellaneous)
  • Confusing DEBUG - Japheth, 19.08.2010, 00:52
    • Confusing DEBUG - EDIT - ecm, 19.08.2010, 01:19
      • Confusing DEBUG - EDIT - Japheth, 19.08.2010, 10:17
        • Confusing DEBUG - ecm, 19.08.2010, 11:00