Mega65 Wiki

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====== Remote Serial Monitor ======

{{http://gurce.net/Logs/images/img_2016_07_27_21_30.png}}

The Remote Serial Monitor is a handy tool to help you debug the MEGA65 System.

Documentation exists for it in the following locations:

  * [[https://docs.google.com/document/d/1fmEUg6hDdWRb2tFZ3n4LG7S1mNP04_SUAW5DrE8zRpk/edit#|C65GS System Notes]]
    * See the "**4.3 Remote Serial Monitor (handy for debugging)**" section
  * [[https://github.com/Ben-401/c65gs/blob/dockit/doc/monitor.md]]
    * Some extra usage info exists in this page of Ben's fork of the github repo
  * Typing "**?**" within the monitor (via your terminal app) to see a list of slightly outdated commands


===== m65dbg =====

I'm currently developing a comms tool to enhance debugging support for the mega65.

It's still early days, but some present perks are:

  * It preserves the history of past commands typed (via the readline library, eg, you can use CTRL-R to do a reverse search through past commands)
  * Pressing 'ENTER' key will repeat the last command (handy when using the 'M' command to dump out consecutive chunks of memory)
  * Can disassemble the code at the current pc as you step through
  * If you run the app in the path containing the *.list files for your project (and your *.list files were generated via a newly-tweaked version of Ophis that provided more verbose output in .list files), then you will also see the .a65 source-code line as you step through
  * If you run the app in the path containing the *.map files for your project, you can use symbol-names in-place of raw addresses for many of the m65dbg commands.

The source for the m65dbg app is available here:

  * https://github.com/MEGA65/m65dbg


==== Building ====

  * You will need to install a few pre-requisite libraries (via apt-get/yum/zypper, or cygwin's setup.exe)
    * **libreadline-devel**
  * **git clone https://github.com/MEGA65/m65dbg**
  * **cd m65dbg**
  * **make**
  * This will produce the "**m65dbg**" executable (or, "**m65dbg.exe**", in Cygwin's case)

==== Walkthrough ====

For a youtube video walkthrough, please visit:

  * https://www.youtube.com/watch?v=2VT8yB3odhg

Here's some written points below:

  * Presently, I'm building it for windows-cygwin, but I'm hopeful with a bit of tweaking of the Makefile and source (particularly relating to libreadline), it'll build fine in macosx and linux.
  * Presently, inside the "main.c" file, I've hard-coded the serial-port to point to "**/dev/ttyS4**", as that's what it appears like on my system. This probably isn't ideal, as everyone's serial-port device names will be different. So for now, please just replace that line with the device-name on your system :)
  * Try the following steps:
    * **./m65dbg**
    * **r** (to print out current registers)
    * **b<addr>** = a raw command to set a hardware breakpoint
    * **t1** (to turn trace mode on, a bit like ctrl-c breaking inside gdb)
    * **t0** (to turn trace mode off, a bit like doing 'c'/continue in gdb)
    * **n** (my 'next'/step-over command, which uses the hardware's step-into command multiple times, can be very slow)
    * **s** (my 'step-into' command, which just calls the hardware's step-into)
    * **[ENTER]** key will repeat the last command
    * **finish** (my 'step-out-of' command, which calls 'n'/next multiple times, can be very slow, depending on how busy the current function is)
    * **pb/pw/pd/ps <addr>** = prints byte/word/dword/string values at the given address
    * typing "**help**" will give you the list of m65dbg commands, while typing "**?**" will give you the list of raw commands.