mirror of
https://github.com/mnaberez/py65.git
synced 2024-11-18 15:06:35 +00:00
418 lines
11 KiB
ReStructuredText
418 lines
11 KiB
ReStructuredText
***********************************************
|
|
Py65 - 6502 Microprocessor Simulation in Python
|
|
***********************************************
|
|
|
|
:Author: Mike Naberezny
|
|
:Version: |version|
|
|
|
|
.. topic:: Overview
|
|
|
|
Simulate 6502-based microcomputer systems in Python.
|
|
|
|
Using the Monitor
|
|
=================
|
|
|
|
Introduction
|
|
------------
|
|
|
|
Py65 includes a program called Py65Mon that functions as a machine language
|
|
monitor. This kind of program is sometimes also called a debugger. Py65Mon
|
|
provides a command line with many convenient commands for interacting with the
|
|
simulated 6502-based system.
|
|
|
|
The monitor is started using the ``py65mon`` command::
|
|
|
|
$ py65mon
|
|
|
|
Py65 Monitor
|
|
|
|
PC AC XR YR SP NV-BDIZC
|
|
6502: 0000 00 00 00 ff 00110000
|
|
.
|
|
|
|
Once the monitor has started, it will display a register dump and the
|
|
dot prompt. You can then enter commands for the monitor at this prompt.
|
|
|
|
Py65Mon uses commands that are very similar to those used by the monitor
|
|
included with the `VICE emulator <http://viceteam.org>`_ for Commodore
|
|
computers. You can get a list of available commands with ``help`` or
|
|
help on a specific command with ``help command``.
|
|
|
|
Number Systems
|
|
--------------
|
|
|
|
When working with Py65Mon, you will frequently need to enter numbers, addresses,
|
|
and ranges of addresses. Almost all Py65 command support entering numbers in
|
|
binary, decimal, and hexadecimal.
|
|
|
|
Numbers can be entered with a prefix to specify the radix, e.g. ``$c000``
|
|
instructs Py65Mon that the number ``c000`` is hexadecimal. The following
|
|
prefixes are supported:
|
|
|
|
- ``$c000``: The dollar sign indicates hexadecimal.
|
|
- ``+828``: The plus sign indicates decimal.
|
|
- ``%0101``: The percent sign indicates binary.
|
|
|
|
Numbers can also be entered without a prefix. Most of the time, working in
|
|
hexadecimal will be the most convenient so this is the default radix. The
|
|
number ``c000`` will be assumed to be hexadecimal unless the default radix
|
|
is changed using the ``radix`` command.
|
|
|
|
Address Ranges
|
|
--------------
|
|
|
|
Some commands accept a range of memory addresses::
|
|
|
|
.disassemble ff80:ff84
|
|
$ff80 d8 CLD
|
|
$ff81 a2 ff LDX #$ff
|
|
$ff83 9a TXS
|
|
$ff84 a0 1c LDY #$1c
|
|
|
|
The syntax for a range is ``start:end``. Each of the two parts may have
|
|
a prefix to indicate the radix, or no prefix to use the default radix.
|
|
|
|
Sometimes it is useful to have the starting and ending address in a range
|
|
be the same, such as when you want to inspect a single byte of memory. In
|
|
this case, you can enter ``ff80:ff80`` or simply ``ff80``.
|
|
|
|
Assigning Labels
|
|
----------------
|
|
|
|
Large assembly language programs may have hundreds of procedures. It is
|
|
difficult to remember the memory address of each procedure and the addresses
|
|
may change if the program is reassembled.
|
|
|
|
You can add a label for any memory address using the ``add_label`` command.
|
|
This label can then be used anywhere the address could be used::
|
|
|
|
.add_label ff80 start
|
|
|
|
.disassemble start
|
|
$ff80 d8 CLD
|
|
|
|
When using labels, you can also specify an offset (plus or minus)::
|
|
|
|
.disassemble start:start+4
|
|
$ff80 d8 CLD
|
|
$ff81 a2 ff LDX #$ff
|
|
$ff83 9a TXS
|
|
$ff84 a0 1c LDY #$1c
|
|
|
|
Offsets are interpreted like any other numbers. In the example above,
|
|
``start+4`` implies that the offset (``4``) uses the default radix. This
|
|
could also be written as ``start+$04`` for explicit hexadecimal.
|
|
|
|
Command Reference
|
|
=================
|
|
|
|
.. describe:: add_label <address> <label>
|
|
|
|
Assign a label to an address::
|
|
|
|
.add_label f000 start
|
|
|
|
Once defined, the label may be used in place of the address in other
|
|
commands. If a label already exists at the address, it will be silently
|
|
overwritten.
|
|
|
|
.. describe:: assemble <address> [<statement>]
|
|
|
|
Assemble a single statement at an address::
|
|
|
|
.assemble c000 lda $a0,x
|
|
$c000 b5 a0 LDA $a0,X
|
|
|
|
If no statement is given, interactive assembly mode will start::
|
|
|
|
.assemble c000
|
|
$c000
|
|
|
|
Enter a statement and it will be assembled at the current address. The
|
|
address will then be incremented and another statement may be entered.
|
|
Press Enter or Return without entering a statement to exit interactive
|
|
assembly mode.
|
|
|
|
If you have defined labels with add_label, you may use those labels in
|
|
the address and the operand.
|
|
|
|
.. describe:: cd <path>
|
|
|
|
Change the current working directory to the path specified::
|
|
|
|
.cd /path/to/my/files
|
|
/path/to/my/files
|
|
|
|
After changing the directory, the new working directory will be displayed.
|
|
The default working directory is the directory from which the monitor was
|
|
started.
|
|
|
|
.. describe:: cycles
|
|
|
|
Display the number of cycles that the microprocessor has run
|
|
since it was last reset::
|
|
|
|
.cycles
|
|
12
|
|
|
|
.. describe:: delete_label <label>
|
|
|
|
Delete a label that was previously defined with ``add_label``::
|
|
|
|
.delete_label foo
|
|
|
|
If the label does not exist, the command will fail silently.
|
|
|
|
.. describe:: disassemble <address_range>
|
|
|
|
Disassemble a range of memory::
|
|
|
|
.disassemble ff80:ff84
|
|
$ff80 d8 CLD
|
|
$ff81 a2 ff LDX #$ff
|
|
$ff83 9a TXS
|
|
$ff84 a0 1c LDY #$1c
|
|
|
|
The disassembly will use the instruction set of the selected MPU. For
|
|
example, the extra instructions of the 65C02 will only be displayed if
|
|
a 65C02 MPU is selected. On an NMOS 6502, those instructions would be
|
|
disassembled as ``???``.
|
|
|
|
If labels have been defined, they will be substituted for
|
|
addresses in the operands.
|
|
|
|
.. describe:: fill <address_range> <byte> [<byte> <byte> ...]
|
|
|
|
Fill a range of memory using one or more bytes from the list::
|
|
|
|
.fill c000:c003 aa bb
|
|
Wrote +4 bytes from $c000 to $c003
|
|
|
|
.mem c000:c003
|
|
c000: aa bb aa bb
|
|
|
|
If the range is larger than the number of bytes in the list, the list
|
|
will repeat as shown above.
|
|
|
|
.. describe:: goto <address>
|
|
|
|
Set the program counter to an address and resume execution::
|
|
|
|
.goto c000
|
|
|
|
.. describe:: help [<command>]
|
|
|
|
Display help for all commands or a single command. If no command is
|
|
given, a list of commands will be displayed::
|
|
|
|
.help
|
|
|
|
If a command is given, help for that comand is displayed::
|
|
|
|
.help disassemble
|
|
disassemble <address_range>
|
|
Disassemble instructions in the address range.
|
|
|
|
.. describe:: load <filename> <address>
|
|
|
|
Load a binary file into memory starting at the address specified::
|
|
|
|
.load hello.bin c000
|
|
Wrote +29 bytes from $c000 to $c01c
|
|
|
|
The file will be loaded relative to the current working directory. You
|
|
may also specify an absolute path. If the filename contains spaces, use
|
|
quotes around it::
|
|
|
|
.load "say hello.bin" c000
|
|
Wrote +29 bytes from $c000 to $c01c
|
|
|
|
.. note::
|
|
|
|
Unlike the VICE monitor, Py65Mon's ``load`` command does not expect
|
|
the first two bytes to be a Commodore-style load address. It will start
|
|
reading the data at byte 0, not byte 2.
|
|
|
|
If the filename is a URL, it will be retrieved::
|
|
|
|
.load https://github.com/mnaberez/py65/raw/0.11/examples/ehbasic.bin 0000
|
|
Wrote +65536 bytes from $0000 to $ffff
|
|
|
|
.. describe:: mem <address_range>
|
|
|
|
Display the contents of memory an address range::
|
|
|
|
.mem ff80:ffa0
|
|
ff80: d8 a2 ff 9a a0 1c b9 bb ff 99 04 02 88 d0 f7 b9 d8 ff
|
|
ff92: f0 06 20 a6 e0 c8 d0 f5 20 a3 e0 90 fb 29 df
|
|
|
|
The contents will be wrapped to the terminal width specified by the
|
|
``width`` command.
|
|
|
|
.. describe:: mpu [<mpu_name>]
|
|
|
|
Display or set the current microprocessor. If no argument is given, the
|
|
current microprocessor will be displayed::
|
|
|
|
.mpu
|
|
Current MPU is 6502
|
|
Available MPUs: 6502, 65C02, 65Org16
|
|
|
|
If an argument is given, the microprocessor will be changed::
|
|
|
|
.mpu 65C02
|
|
Reset with new MPU 65C02
|
|
|
|
The default microprocessor is ``6502``, the original NMOS 6502 from
|
|
MOS Technology.
|
|
|
|
.. describe:: pwd
|
|
|
|
Display the current working directory::
|
|
|
|
.pwd
|
|
/home/mnaberez
|
|
|
|
.. describe:: quit
|
|
|
|
Quit the monitor::
|
|
|
|
.quit
|
|
|
|
.. describe:: radix [<H|D|O|B>]
|
|
|
|
Display or set the default radix that is assumed for numbers that have no prefix.
|
|
If no argument is given, the default radix is displayed::
|
|
|
|
.radix
|
|
Default radix is Hexadecimal
|
|
|
|
If an argument is given, the default radix will be changed::
|
|
|
|
.radix d
|
|
Default radix is Decimal
|
|
|
|
The default radix may be changed to Hexadecimal, Decimal, Octal, or Binary.
|
|
|
|
.. describe:: registers [<name=value>, <name=value>, ...>]
|
|
|
|
Display or change the registers of the microprocessor. If no arguments are
|
|
given, the registers are displayed::
|
|
|
|
.registers
|
|
|
|
PC AC XR YR SP NV-BDIZC
|
|
6502: 0000 00 00 00 ff 00110000
|
|
|
|
Registers can changed giving ``name=value``, separated by commas if
|
|
multiple registers are to be changed::
|
|
|
|
.registers a=02, x=04
|
|
|
|
PC AC XR YR SP NV-BDIZC
|
|
6502: 0000 02 04 00 ff 00110000
|
|
|
|
.. describe:: reset
|
|
|
|
Reset the microprocessor to its default state. All memory will
|
|
also be cleared::
|
|
|
|
.reset
|
|
|
|
.. describe:: return
|
|
|
|
Continue execution and return to the monitor just before the next
|
|
RTS or RTI is executed::
|
|
|
|
.return
|
|
|
|
.. describe:: save <filename> <start_address> <end_address>
|
|
|
|
Save the specified memory range to disk as a binary file::
|
|
|
|
.save hello.bin c000 c01c
|
|
Wrote +29 bytes from $c000 to $c01c
|
|
|
|
The file will be saved relative to the current working directory. You
|
|
may also specify an absolute path. If the filename contains spaces, use
|
|
quotes around it::
|
|
|
|
.save "say hello.bin" c000 c01c
|
|
Wrote +29 bytes from $c000 to $c01c
|
|
|
|
.. note::
|
|
|
|
Unlike the VICE monitor, Py65Mon's ``save`` command does not write
|
|
the first two bytes as a Commodore-style load address. It will start
|
|
writing the data at byte 0, not byte 2.
|
|
|
|
.. describe:: show_labels
|
|
|
|
Display labels that have been defined with ``add_label``::
|
|
|
|
.show_labels
|
|
ffd2: charout
|
|
|
|
.. describe:: step
|
|
|
|
Execute a single instruction at the program counter. After the instruction
|
|
executes, the next instruction is disassembled and printed::
|
|
|
|
PC AC XR YR SP NV-BDIZC
|
|
6502: 0000 00 00 00 ff 00110000
|
|
.registers pc=c000
|
|
|
|
PC AC XR YR SP NV-BDIZC
|
|
6502: c000 00 00 00 ff 00110000
|
|
.step
|
|
$c002 a9 42 LDA #$42
|
|
|
|
PC AC XR YR SP NV-BDIZC
|
|
6502: c002 00 00 00 ff 00110000
|
|
.
|
|
|
|
In the example above, the instruction at ``$C000`` executes and the monitor
|
|
prompt returns.
|
|
|
|
.. note::
|
|
|
|
After the instruction executes, the disassembly of the **next** instruction
|
|
is printed. This allows you to see what will be executed on the next step.
|
|
|
|
.. describe:: tilde
|
|
|
|
Display a number in the supported number systems::
|
|
|
|
.~ c000
|
|
+49152
|
|
$c000
|
|
140000
|
|
1100000000000000
|
|
|
|
The number will be displayed in this order: decimal, hexadecimal, octal,
|
|
and then binary.
|
|
|
|
.. describe:: version
|
|
|
|
Display version information::
|
|
|
|
.version
|
|
|
|
Py65 Monitor
|
|
|
|
.. describe:: width [<columns>]
|
|
|
|
Display or set the terminal width. The width is used to wrap the output
|
|
of some commands like ``mem``. With no argument, the current width is
|
|
displayed::
|
|
|
|
.width
|
|
Terminal width is 78
|
|
|
|
If a column count is given, the width will be changed::
|
|
|
|
.width 130
|
|
Terminal width is 130
|
|
|
|
The number of columns is always specified as a decimal number.
|