Mostek z80 - Examples, S Command

3-40
Fonnat (4) is used to change the display mode for single-step operation. The
system powers up in the disassembly. If the third operand "m" is "D" the
disassembly mode is specified, otherwise the register mode is specified.
Once a particular mode is specified, the mode is used until changed by the
user. When the disassembly mode is used, instead of printing the Z80
registers each step, the Program Counter and Accumulator/Flags (before
execution), the instruction opcode disassembled, and the Program Counter and
AccLmulator/Flags (after execution of the instruction) is printed for each
step.
Interrupts (maskable or non-maskable) can occur during single-step
execution. When an interrupt occurs, the program will begin single-step
execution in the interrupt handling routine. WAIT states and DMA operations
can also occur during single step execution. 'Ihese occur at full speed and
are transparent to the user.
3.61 EXAMPLES, S COMMAND
,S !tCR)
< step from address 0
PC AF I IF BC DE HL DISASSEMBLY
0000 FFAS 0040 0101 FFFF 0200 LD A,0
0002 00A8 0040 0101 FFFF 0200 INC A
0003 0100 0040 0101 FFFF 0200 INC A
0004 0200 0040 0101 FFFF 0200 CPL
,S (CR) < resume stepping
19-USEC
IX IY SP
BFt'F
FFFF 01F0
BFFF FFFF 01F0
BFFF FFFF 01F0
BFFF FFFF 01F0
7 USEC
11 USEC(CR)
15 USEC(CR)
0005 FD3A 0040 0101 FFFF 0200 INC A
0006 FEAS 0040 0101 FFFF 0200 INC A
BFFF FFFF 01F0 23 USEC(CR)
BFFF FFFF 01F0 •
,S 0,4(CR) < multi-step
- -- < see R command for addi tiona1 example
PC AF I IF BC DE HL DISASSEMBLY IX IY SP
0000 0100 0040 0101
FFFF 0200 LD A,0 BFFF FFFF 01F0
0002 0000 0040 0101 FFFF 0200 INC A BFFF FFF'F 01F0
0003 0100 0040 0101
FFFF 0200 INC A BFFF FFFF 01F0
0004 0200 0040 0101
FFFF 0200 CPL BFFF FFFF 01F0
0005
FD3A 0040 0101 FFFF 0200 INC A BFFF FFFF 01F0
,
,
7 USEe
11 USEe
15 USEC
19 USEe