Zxdb supports the following commands for dealing with assembly language:
di: Disassemble at the current location (or a given location)
ni: Step to the next instruction, stepping over function calls.
si: Step the next instruction, following function calls.
regs: Get the CPU registers.
zxdb maintains information about whether the last command was an assembly command or a source-code
and will show that information on stepping or breakpoint hits. To switch to assembly-language mode,
disassemble, and to switch back to source-code mode, type