Int 21 Fn 3F  - Turbo Debug Hardware Breakpoints - Read Status Block       [G]

   AH = 3Fh
   BX = handle for character device "TDHDEBUG"
   CX = number of bytes to read
   DS:DX -> buffer for status block (see #1093)

Return: CF clear if successful
       AX = number of bytes actually read
   CF set on error
       AX = error code (05h,06h) (see #1366 at AH=59h/BX=0000h)

See Also: AH=40h"Turbo Debug"

(Table 1092)
Values for status of Turbo Debugger command:
 00h   successful
 01h   invalid handle
 02h   no more breakpoints available
 03h   hardware does not support specified breakpoint type
 04h   previous command prevents execution
 05h   debugger hardware not found
 06h   hardware failure
 07h   invalid command
 08h   driver not initialized yet
 FEh   recursive entry (hardware breakpoint inside hw bp handler)

Format of Turbo Debugger status block:
Offset Size    Description (Table 1093)
 00h   BYTE    status of command (see #1092)
---status for command 01h---
 01h   WORD    device driver interface version number (currently 1)
 03h   WORD    device driver software version
 05h   BYTE    maximum simultaneous hardware breakpoints
 06h   BYTE    configuration bits (see #1094)
 07h   BYTE    supported breakpoint types (see #1095)
 08h   WORD    supported addressing match modes (see #1096)
 0Ah   WORD    supported data matches (see #1097)
 0Ch   BYTE    maximum data match length (01h, 02h, or 04h)
 0Dh   WORD    size of onboard memory (in KB)
 0Fh   WORD    maximum number of trace-back events
 11h   WORD    hardware breakpoint enable byte address segment (0000h if not
         supported)
---status for command 04h---
 01h   BYTE    handle to use when referring to the just-set breakpoint

Bitfields for Turbo Debugger configuration bits:
Bit(s) Description (Table 1094)
 0 CPU and DMA accesses are distinct
 1 can detect DMA transfers
 2 supports data mask
 3 hardware pass counter on breakpoints
 4 can match on data as well as addresses

Bitfields for Turbo Debugger supported breakpoint types:
Bit(s) Description (Table 1095)
 0 memory read
 1 memory write
 2 memory read/write
 3 I/O read
 4 I/O write
 5 I/O read/write
 6 instruction fetch

Bitfields for Turbo Debugger supported addressing match modes:
Bit(s) Description (Table 1096)
 0 any address
 1 equal to test value
 2 not equal
 3 above test value
 4 below test value
 5 below or equal
 6 above or equal
 7 within range
 8 outside range

Bitfields for Turbo Debugger supported data matches:
Bit(s) Description (Table 1097)
 0 any data
 1 equal to test value
 2 not equal
 3 above test value
 4 below test value
 5 below or equal
 6 above or equal
 7 within range
 8 outside range