====== MAME Debugger General Commands ======
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===== help =====
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**Syntax:** ''help <topic>''

Get help on a particular topic.
===== do =====
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**Syntax:** ''do <expression>''

The //do// command simply evaluates the given ''<expression>''. This is typically used to set or modify variables.

**Examples:**
  * ''do pc = 0'' – Sets the register ''pc'' to ''0''.

The word //do// is optional, thus

  * ''pc=0'' – will also set the ''pc'' register to ''0''.
===== symlist =====
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**Syntax:** ''symlist [<cpunum>]''

Lists registered symbols. If ''<cpunum>'' is not specified, then symbols in the global symbol table are displayed; otherwise, the symbols for ''<cpunum>'''s specific CPU are displayed. Symbols are listed alphabetically. Read-only symbols are flagged with an asterisk.

**Examples:**
  * ''symlist'' – Displays the global symbol table.
  * ''symlist 2'' – Displays the symbols specific to CPU #2.
===== softreset =====
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**Syntax:** ''softreset''

Executes a soft reset.

**Examples:**
  * ''softreset'' – Executes a soft reset.
===== hardreset =====
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**Syntax:** ''hardreset''

Executes a hard reset.

**Examples:**
  * ''hardreset'' – Executes a hard reset.
===== print =====
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**Syntax:** ''print <item>[,…]''

The //print// command prints the results of one or more expressions to the debugger console as hexadecimal values.

**Examples:**
  * ''print pc'' – Prints the value of ''pc'' to the console as a hex number.
  * ''print a,b,a+b'' – Prints a, b, and the value of a+b to the console as hex numbers.
===== printf =====
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**Syntax:** ''printf <format>[,<item>[,…]]''

The //printf// command performs a C-style printf to the debugger console. Only a very limited set of formatting options are available:

  * ''%[0][<n>]d'' – prints ''<item>'' as a decimal value with optional digit count and zero-fill
  * ''%[0][<n>]x'' – prints ''<item>'' as a hexadecimal value with optional digit count and zero-fill

All remaining formatting options are ignored. Use ''%%'' together to output a ''%'' character. Multiple lines can be printed by embedding a ''\n'' in the text.

**Examples:**
  * ''printf "PC=%04X",pc'' – Prints ''PC=<pcval>'' where ''<pcval>'' is displayed in hexadecimal with 4 digits with zero-fill.
  * ''printf "A=%d, B=%d\nC=%d",a,b,a+b'' – Prints ''A=<aval>, B=<bval>'' on one line, and ''C=<a+bval>'' on a second line.
===== logerror =====
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**Syntax:** ''logerror <format>[,<item>[,…]]''

The //logerror// command performs a C-style printf to the error log. Only a very limited set of formatting options are available:

  * ''%[0][<n>]d'' – logs ''<item>'' as a decimal value with optional digit count and zero-fill
  * ''%[0][<n>]x'' – logs ''<item>'' as a hexadecimal value with optional digit count and zero-fill

All remaining formatting options are ignored. Use two ''%'' together to output a ''%'' character. Multiple lines can be printed by embedding a ''\n'' in the text.

**Examples:**
  * ''logerror "PC=%04X",pc'' – Logs ''PC=<pcval>'' where ''<pcval>'' is displayed in hexadecimal with 4 digits with zero-fill.
  * ''logerror "A=%d, B=%d\nC=%d",a,b,a+b'' – Logs ''A=<aval>, B=<bval>'' on one line, and ''C=<a+bval>'' on a second line.
===== tracelog =====
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**Syntax:** ''tracelog <format>[,<item>[,…]]''

The //tracelog// command performs a C-style printf and routes the output to the currently open trace file (see the [[debugger:execution#trace|trace]] command for details). If no file is currently open, //tracelog// does nothing. Only a very limited set of formatting options are available. See the [[#printf|printf]] help for details.

**Examples:**
  * ''tracelog "PC=%04X",pc'' – Outputs ''PC=<pcval>'' where ''<pcval>'' is displayed in hexadecimal with 4 digits with zero-fill.
  * ''tracelog "A=%d, B=%d\nC=%d",a,b,a+b'' – Outputs ''A=<aval>, B=<bval>'' on one line, and ''C=<a+bval>'' on a second line.
===== snap =====
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**Syntax:** ''snap [[<filename>], <scrnum>]''

The //snap// command takes a snapshot of the current video display and saves it to the configured snapshot directory. If ''<filename>'' is specified explicitly, a single screenshot for ''<scrnum>'' is saved under the requested filename. If ''<filename>'' is omitted, all screens are saved using the same default rules as the “save snapshot” key in MAME proper.

**Examples:**
  * ''snap'' – Takes a snapshot of the current video screen and saves to the next non-conflicting filename in the configured snapshot directory.
  * ''snap shinobi'' – Takes a snapshot of the current video screen and saves it as ''shinobi.png'' in the configured snapshot directory.
===== source =====
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**Syntax:** ''source <filename>''

The //source// command reads in a set of debugger commands from a file and executes them one by one, similar to a batch file.

**Examples:**
  * ''source break_and_trace.cmd'' – Reads in debugger commands from ''break_and_trace.cmd'' and executes them.
===== quit =====
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**Syntax:** ''quit''

The //quit// command exits MESS immediately.