To single-step from one machine instruction to the next machine instruction, use the nexti command or the stepi command
The nexti command and the stepi command behave the same as their source-code level counterparts: the nexti command steps over functions, the stepi command steps into a function called by the next instruction, stopping at the first instruction in the called function. The command forms are also the same.
The output from the nexti command and the stepi command differ from the corresponding source level commands in two ways:
The output includes the address of the instruction at which the program is stopped (instead of the source code line number).
The default output contains the disassembled instruction instead of the source code line.
For example:
(dbx) func hand::ungrasp (dbx) nexti ungrasp +0x18: call support (dbx)
For more information, see nexti Command and stepi Command.