diff --git a/antlr/pdp7asm.g4 b/antlr/pdp7asm.g4
new file mode 100644
index 0000000..c1d77d1
--- /dev/null
+++ b/antlr/pdp7asm.g4
@@ -0,0 +1,162 @@
+/*
+BSD License
+
+Copyright (c) 2013, Tom Everett
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+2. Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+3. Neither the name of Tom Everett nor the names of its contributors
+   may be used to endorse or promote products derived from this software
+   without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+grammar pdp7asm;
+
+prog
+    : line+
+    ;
+
+line
+    : (label? declarations? comment? eol)
+    | eol 
+    ;
+
+declarations
+    : declaration (';' declaration)*
+    ;
+
+declaration
+    : opcode argument+
+    ;
+
+argument
+    : expression
+    ;
+
+expression 
+    : multiplyingExpression ((PLUS|MINUS) multiplyingExpression)*
+    ;
+
+multiplyingExpression  
+    : atom ((TIMES|DIV) atom)*
+    ;
+
+atom 
+    : variable
+    | LOC
+    | RELOC
+    | STRING
+    | DECIMAL
+    | DECIMAL_MINUS
+    | OCTAL
+    | HEX  
+    ;
+
+eol
+    : EOL
+    ;
+
+comment
+    : COMMENT
+    ;
+
+label
+    : IDENTIFIER ':'
+    ;
+
+variable
+    : IDENTIFIER
+    ;
+
+opcode
+    : 'jms'
+    | 'dac'
+    | 'lac'
+    | 'and'
+    | 'jmp'
+    | 'tad'
+    | 'sad'
+    | 'sys'
+    | 'sna'
+    | 'spa'
+    ;
+
+LOC
+    : '.'
+    ;
+
+RELOC
+    : '..'
+    ;
+
+PLUS 
+    : '+'
+    ;
+
+MINUS 
+    : '-'
+    ;
+
+TIMES 
+    : '*'
+    ;
+
+DIV 
+    : '/'
+    ;
+
+IDENTIFIER
+    : [a-zA-Z]+
+    ;
+
+HEX
+    : [0-9a-f]+
+    ;
+
+DECIMAL
+    : 'd' [0-9]+
+    ;
+
+OCTAL
+    : 'o' [0-7]+
+    ;
+
+DECIMAL_MINUS
+    : 'dm' [0-9]+
+    ;
+
+STRING
+    : '<' [a-zA-Z0-9$*,%/]+ '>'
+    ;
+
+COMMENT
+    : '"' ~[\r\n]*
+    ;
+
+EOL
+    : [\r\n]+
+    ;
+
+WS
+    : [ \t] -> skip
+    ;