INT 21 - Turbo Debug HARDWARE BREAKPOINTS - READ STATUS BLOCK AH = 3Fh BX = handle for character device "TDHDEBUG" CX = number of bytes to read DS:DX -> buffer for status block (see #01406) Return: CF clear if successful AX = number of bytes actually read CF set on error AX = error code (05h,06h) (see #01680 at AH=59h/BX=0000h) SeeAlso: AH=40h"Turbo Debug" (Table 01405) 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 01406) 00h BYTE status of command (see #01405) ---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 #01407) 07h BYTE supported breakpoint types (see #01408) 08h WORD supported addressing match modes (see #01409) 0Ah WORD supported data matches (see #01410) 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 01407) 0 CPU(Central Processing Unit) The microprocessor which executes programs on your computer. and DMAsee Direct Memory Access accesses are distinct 1 can detect DMAsee Direct Memory Access 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 01408) 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 01409) 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 01410) 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