t

t[a|c|n|s|x|z][=start_addr][count][addr]

The t command executes one or more instructions along with the default command string and then displays the decoded instruction. If you include the start_addr parameter, tracing starts at the specified address. Otherwise, the command steps through the next machine instruction and then executes the default command string.

The t command uses the hardware trace mode of the Intel microprocessor. Consequently, you can also trace instructions stored in read-only memory (ROM).

Parameters

a

Indicates that an ending address is specified for the trace. Instructions are traced until the address in addr is reached.

c

Suppresses all output and counts instructions traced. An ending address is required for this command. Instructions are traced until the address in addr is reached.

n

Suppresses the register display so just the assembly line is displayed. This works only if the default command, zd, is set to r (the normal setting).

s

Suppresses output; the instruction and count are displayed for each call and the return from that call.

x

Forces the debugger to trace regions of code known to be untraceable (_PGSwitchContext, for example).

z

Allows original trap handler address to be traced into without having to unhook the exception. Use this option instead of vcp d; t; vsp d.

start_addr

Specifies the instruction address at which to start tracing. The equal sign (=) is required.

count

Specifies the number of instructions to execute and trace.

addr

Specifies the instruction address at which to stop tracing.

Example

The following example traces the current position (04BA:011A) and uses the default command string (r command) to display registers:

t

The resulting output is similar to the following:

AX=0E00  BX=00FF  CX=0007  DX=01FF  SP=039D  BP=0000  SI=005C  DI=0000
IP=011A  CS=04BA  DS=04BA  ES=04BA  SS=04BA  NV UP DI NG NZ AC PENC
GDTR=01D700 3677  IDTR=020D7A 03FF  TR=0010  LDTR=0028 IOPL=3 MSW=PM
04BA:011A  CD21          PUSH   21

The following command causes the debugger to execute 16 (10h) instructions beginning at 011A in the current selector:

t=011A 10

The debugger executes and displays the results of the default command string for each instruction. The display is scrolled until the last instruction is executed. Press the CTRL+S key combination to stop the scrolling and CTRL+Q to resume.