diff --git a/slinky/builtins.c b/slinky/builtins.c
index 38b22a5..2fd9e6e 100644
--- a/slinky/builtins.c
+++ b/slinky/builtins.c
@@ -30,6 +30,11 @@
 #include "slinkyTypes.h"
 #include "slinkyGlobals.h"
 #include "slinkyExpressions.h"
+#include "builtins.h"
+#include "errorStuff.h"
+#include "expr.h"
+#include "link.h"
+#include "relocate.h"
 #include <string.h>
 
 #define getSymbol() ((symbolType *)getNumber())
@@ -409,7 +414,6 @@ symbolLookupBIF(argCount)
 {
 	symbolType	*symbol;
 	stringType	*symbolName;
-	symbolType	*lookupGlobalSymbol();
 
 	if (argCount < 1) {
 		tooFewArgs(argCount, "symbolLookup");
diff --git a/slinky/builtins.h b/slinky/builtins.h
new file mode 100644
index 0000000..703914e
--- /dev/null
+++ b/slinky/builtins.h
@@ -0,0 +1,24 @@
+#ifndef BUILTINS_H_
+#define BUILTINS_H_
+
+#include "slinkyTypes.h"
+
+void tooFewArgs(int argCount, stringType *name);
+void tooManyArgs(int argCount, stringType *name);
+stringType *atasciiBIF(int argCount);
+stringType *atasciiColorBIF(int argCount);
+bool isAbsoluteValueBIF(int argCount);
+bool isConditionCodeBIF(int argCount);
+bool isDefinedBIF(int argCount);
+bool isExternalBIF(int argCount);
+int nthCharBIF(int argCount);
+int printfBIF(int argCount);
+stringType *strcatBIF(int argCount);
+int strcmpBIF(int argCount);
+int strcmplcBIF(int argCount);
+int strlenBIF(int argCount);
+char *substrBIF(int argCount);
+addressType symbolLookupBIF(int argCount);
+stringType *symbolNameBIF(int argCount);
+
+#endif
diff --git a/slinky/debugPrint.c b/slinky/debugPrint.c
index 87048e9..add444b 100644
--- a/slinky/debugPrint.c
+++ b/slinky/debugPrint.c
@@ -31,7 +31,7 @@
 
 #include "slinkyTypes.h"
 #include "slinkyGlobals.h"
-
+#include "debugPrint.h"
 
 static char *modeStrings[2] = {
 		"abs",
diff --git a/slinky/debugPrint.h b/slinky/debugPrint.h
new file mode 100644
index 0000000..8112886
--- /dev/null
+++ b/slinky/debugPrint.h
@@ -0,0 +1,14 @@
+#ifndef DEBUG_PRINT_H_
+#define DEBUG_PRINT_H_
+
+#include "slinkyTypes.h"
+
+void printCode(int startAddress, int endAddress, int mode);
+void printReference(expressionReferenceType *reference);
+void printReferenceFixup(expressionReferenceType *reference);
+void printSymbol(int symbolTag, symbolType *symbol);
+void printLoadMapSymbol(symbolType *symbol);
+void printGlobalSymbols(void);
+void printExpression(expressionPCType expression, int length);
+
+#endif
diff --git a/slinky/errorStuff.c b/slinky/errorStuff.c
index 4166f81..ede5892 100644
--- a/slinky/errorStuff.c
+++ b/slinky/errorStuff.c
@@ -29,6 +29,7 @@
 
 #include "slinkyTypes.h"
 #include "slinkyGlobals.h"
+#include "errorStuff.h"
 
 #include <stdarg.h>
 
diff --git a/slinky/errorStuff.h b/slinky/errorStuff.h
new file mode 100644
index 0000000..f1ec7c5
--- /dev/null
+++ b/slinky/errorStuff.h
@@ -0,0 +1,8 @@
+#ifndef ERROR_STUFF_H_
+#define ERROR_STUFF_H_
+
+#include "slinkyTypes.h"
+
+void error(errorType theError, ...);
+
+#endif
diff --git a/slinky/expr.c b/slinky/expr.c
index 3eb59c7..6673f4b 100644
--- a/slinky/expr.c
+++ b/slinky/expr.c
@@ -30,6 +30,9 @@
 #include "slinkyTypes.h"
 #include "slinkyGlobals.h"
 #include "slinkyExpressions.h"
+#include "expr.h"
+#include "errorStuff.h"
+#include "initialize.h"
 #include "y.tab.h"
 
 #define overSymbol() (pc+=sizeof(symbolType *))
@@ -41,12 +44,6 @@
 #define nextByte(byt) (byt = *pc++)
 #define intOp(byt) (byt+256)
 
-addressType evaluateExpression();
-void skipArray();
-void skipClause();
-void skipString();
-void skipExpression();
-
 static bool		hitFreturn = FALSE;
 static addressType	functionResult;
 
diff --git a/slinky/expr.h b/slinky/expr.h
new file mode 100644
index 0000000..4321f9a
--- /dev/null
+++ b/slinky/expr.h
@@ -0,0 +1,57 @@
+#ifndef EXPR_H_
+#define EXPR_H_
+
+#include "slinkyTypes.h"
+
+int getNumber(void);
+addressType evaluateArray(void);
+addressType evaluateAssert(void);
+addressType evaluateBinop(void);
+addressType evaluateBlock(void);
+addressType evaluateConditionCode(void);
+void pushSymbol(symbolType *symbol, addressType value);
+void bindFunctionArguments(functionType *theFunction, int argCount);
+void undoBindings(void);
+addressType evaluateFreturn(void);
+addressType evaluateBuiltinFunctionCall(void);
+addressType evaluateFunctionCall(void);
+addressType evaluateHere(void);
+addressType evaluateMdefine(void);
+addressType evaluateMdoUntil(void);
+addressType evaluateMdoWhile(void);
+addressType evaluateMfor(void);
+addressType evaluateMif(void);
+bool evaluateClause(addressType pattern);
+addressType evaluateMswitch(void);
+addressType evaluateMwhile(void);
+addressType evaluateMvariable(void);
+addressType evaluateNumber(void);
+addressType evaluateRelocatableNumber(void);
+addressType evaluatePerform(void);
+addressType evaluatePostop(void);
+addressType evaluatePreop(void);
+addressType evaluateString(void);
+addressType evaluateSymbol(void);
+addressType evaluateUnop(void);
+addressType evaluateExpression(void);
+void skipArray(void);
+void skipAssert(void);
+void skipBinop(void);
+void skipBlock(void);
+void skipFunctionCall(void);
+void skipMdefine(void);
+void skipMdoUntil(void);
+void skipMdoWhile(void);
+void skipMfor(void);
+void skipMif(void);
+void skipClause(void);
+void skipMswitch(void);
+void skipMvariable(void);
+void skipMwhile(void);
+void skipPostop(void);
+void skipPreop(void);
+void skipString(void);
+void skipUnop(void);
+void skipExpression(void);
+
+#endif
diff --git a/slinky/initialize.c b/slinky/initialize.c
index 3905f35..c0bfcf5 100644
--- a/slinky/initialize.c
+++ b/slinky/initialize.c
@@ -29,6 +29,12 @@
 
 #include "slinkyTypes.h"
 #include "slinkyGlobals.h"
+#include "initialize.h"
+#include "errorStuff.h"
+#include "main.h"
+
+#include <string.h>
+#include <unistd.h>
 
 static char	*outputFileName;
 
@@ -52,9 +58,6 @@ initializeStuff(argc, argv)
 	int	 mapFilesFound;
 	char	*mapFileName;
 
-	void	 queueInputFile();
-	void	 queueLoadAddress();
-
 	currentFileName = "<command line>";
 	errorFlag = FALSE;
 	packFlag = FALSE;
diff --git a/slinky/initialize.h b/slinky/initialize.h
new file mode 100644
index 0000000..2d3de4a
--- /dev/null
+++ b/slinky/initialize.h
@@ -0,0 +1,11 @@
+#ifndef INITIALIZE_H_
+#define INITIALIZE_H_
+
+#include "slinkyTypes.h"
+
+void chokePukeAndDie(void);
+void initializeStuff(int argc, char **argv);
+void queueInputFile(char *name);
+void queueLoadAddress(char *addressString);
+
+#endif
diff --git a/slinky/instantiate.c b/slinky/instantiate.c
index 65fc4b1..05bc646 100644
--- a/slinky/instantiate.c
+++ b/slinky/instantiate.c
@@ -31,6 +31,9 @@
 #include "slinkyTypes.h"
 #include "slinkyGlobals.h"
 #include "slinkyExpressions.h"
+#include "errorStuff.h"
+#include "expr.h"
+#include "instantiate.h"
 #include "y.tab.h"
 
 #define overFunction() (pc+=sizeof(functionType *))
@@ -38,10 +41,6 @@
 #define overByte() pc++
 #define nextByte(byt) (byt = *pc++)
 
-void putSymbolPointersIntoArray();
-void putSymbolPointersIntoClause();
-void putSymbolPointersIntoExpression();
-
   void
 putNumber(number)
   int	number;
diff --git a/slinky/instantiate.h b/slinky/instantiate.h
new file mode 100644
index 0000000..78571ca
--- /dev/null
+++ b/slinky/instantiate.h
@@ -0,0 +1,29 @@
+#ifndef INSTANTIATE_H_
+#define INSTANTIATE_H_
+
+#include "slinkyTypes.h"
+
+void putNumber(int number);
+void instantiateSymbol(void);
+void instantiateFunction(void);
+void putSymbolPointersIntoArray(void);
+void putSymbolPointersIntoAssert(void);
+void putSymbolPointersIntoBinop(void);
+void putSymbolPointersIntoBlock(void);
+void putSymbolPointersIntoBuiltinFunctionCall(void);
+void putSymbolPointersIntoFunctionCall(void);
+void putSymbolPointersIntoMdefine(void);
+void putSymbolPointersIntoMdoUntil(void);
+void putSymbolPointersIntoMdoWhile(void);
+void putSymbolPointersIntoMfor(void);
+void putSymbolPointersIntoMif(void);
+void putSymbolPointersIntoClause(void);
+void putSymbolPointersIntoMswitch(void);
+void putSymbolPointersIntoMvariable(void);
+void putSymbolPointersIntoMwhile(void);
+void putSymbolPointersIntoPostop(void);
+void putSymbolPointersIntoPreop(void);
+void putSymbolPointersIntoUnop(void);
+void putSymbolPointersIntoExpression(void);
+
+#endif
diff --git a/slinky/link.c b/slinky/link.c
index 2900ef6..5059186 100644
--- a/slinky/link.c
+++ b/slinky/link.c
@@ -29,6 +29,15 @@
 
 #include "slinkyTypes.h"
 #include "slinkyGlobals.h"
+#include "link.h"
+#include "debugPrint.h"
+#include "errorStuff.h"
+#include "instantiate.h"
+#include "poke.h"
+#include "read.h"
+#include "relocate.h"
+#include "write.h"
+
 /*#define readWord(f,fn) ((getc(f) & 0xFF) | ((getc(f) & 0xFF)<<8))*/
 
 /*
@@ -102,7 +111,6 @@ internalizeOneObjectFile(objectFile)
 	int		 mode;
 	addressType	 startAddress;
 	addressType	 endAddress;
-	bool		 compareSymbolValues();
 
 	currentFileName = objectFile->name;
 	if ((objectFildes = fopen(objectFile->name, "r")) == NULL) {
diff --git a/slinky/link.h b/slinky/link.h
new file mode 100644
index 0000000..2eceb1e
--- /dev/null
+++ b/slinky/link.h
@@ -0,0 +1,19 @@
+#ifndef LINK_H_
+#define LINK_H_
+
+#include "slinkyTypes.h"
+
+bool internalizeOneObjectFile(objectFileListType *objectFile);
+bool strcmplc(char *s1, char *s2);
+bool compareSymbols(symbolType **symbol1, symbolType **symbol2);
+void buildGlobalSymbolTable(objectFileListType *inputFileList);
+bool readem(void);
+codeSegmentHeaderType *locateConflictingSegment(codeSegmentHeaderType *codeSegment);
+void reserveSegment(addressType start, addressType end);
+codeSegmentHeaderType *allocateAbsolute(codeSegmentHeaderType *codeSegment);
+void reserveReservations(void);
+void installSegment(codeSegmentHeaderType *codeSegment);
+void installAbsoluteCodeSegment(codeSegmentHeaderType *codeSegment);
+void linkem(void);
+
+#endif
diff --git a/slinky/main.c b/slinky/main.c
index abcc6a9..89455e7 100644
--- a/slinky/main.c
+++ b/slinky/main.c
@@ -29,7 +29,11 @@
 
 #include "slinkyTypes.h"
 #include "slinkyGlobals.h"
+#include "main.h"
+#include "initialize.h"
+#include "link.h"
 
+int
 main(argc, argv)
   int	argc;
   char *argv[];
@@ -38,8 +42,7 @@ main(argc, argv)
 	linkem();
 	if (errorFlag)
 		chokePukeAndDie();
-	else
-		exit(0);
+	return 0;
 }
 
   void
diff --git a/slinky/main.h b/slinky/main.h
new file mode 100644
index 0000000..c102f42
--- /dev/null
+++ b/slinky/main.h
@@ -0,0 +1,8 @@
+#ifndef MAIN_H_
+#define MAIN_H_
+
+#include "slinkyTypes.h"
+
+void printVersion(void);
+
+#endif
diff --git a/slinky/map.c b/slinky/map.c
index 41f0c5c..dab44a1 100644
--- a/slinky/map.c
+++ b/slinky/map.c
@@ -30,11 +30,9 @@
 
 #include "slinkyTypes.h"
 #include "slinkyGlobals.h"
-
-typedef struct {
-	symbolType	*symbol;
-	stringType	*fileName;
-		      } loadMapTableEntryType;
+#include "map.h"
+#include "debugPrint.h"
+#include "link.h"
 
   int
 compareLoadMapEntries(entry1, entry2)
diff --git a/slinky/map.h b/slinky/map.h
new file mode 100644
index 0000000..294344f
--- /dev/null
+++ b/slinky/map.h
@@ -0,0 +1,14 @@
+#ifndef MAP_H_
+#define MAP_H_
+
+#include "slinkyTypes.h"
+
+typedef struct {
+	symbolType	*symbol;
+	stringType	*fileName;
+		      } loadMapTableEntryType;
+
+int compareLoadMapEntries(loadMapTableEntryType *entry1, loadMapTableEntryType *entry2);
+void outputLoadMap(void);
+
+#endif
diff --git a/slinky/poke.c b/slinky/poke.c
index 94b7b27..89fac42 100644
--- a/slinky/poke.c
+++ b/slinky/poke.c
@@ -31,6 +31,10 @@
 
 #include "slinkyTypes.h"
 #include "slinkyGlobals.h"
+#include "poke.h"
+#include "debugPrint.h"
+#include "errorStuff.h"
+#include "expr.h"
 
   bool
 isWordSized(value)
diff --git a/slinky/poke.h b/slinky/poke.h
new file mode 100644
index 0000000..94c69bd
--- /dev/null
+++ b/slinky/poke.h
@@ -0,0 +1,15 @@
+#ifndef POKE_H_
+#define POKE_H_
+
+#include "slinkyTypes.h"
+
+bool isWordSized(int value);
+bool isByteSized(int value);
+bool isByteOffset(int value);
+int computeRelativeValue(int valueToPoke, codeSegmentHeaderType *codeSegment, int offset);
+int getBaseValue(byte *codeBuffer, int offset, int referenceKind);
+void pokeValue(int value, byte *codeBuffer, int offset, int referenceKind, int trueAddress);
+void fixupReference(expressionReferenceType *reference, codeSegmentHeaderType *codeSegment);
+void pokem(void);
+
+#endif
diff --git a/slinky/read.c b/slinky/read.c
index 242cc4a..aab35b0 100644
--- a/slinky/read.c
+++ b/slinky/read.c
@@ -31,6 +31,12 @@
 
 #include "slinkyTypes.h"
 #include "slinkyGlobals.h"
+#include "read.h"
+#include "debugPrint.h"
+#include "errorStuff.h"
+#include "initialize.h"
+#include "instantiate.h"
+#include "link.h"
 
 #define isAbsolute(symbol) (((symbol)->symbolClass & SYMBOL_ABSOLUTE) != 0)
 #define isRelocatable(symbol) (((symbol)->symbolClass &SYMBOL_RELOCATABLE)!=0)
@@ -520,7 +526,6 @@ readReservations(objectFile, objectFildes)
   FILE			*objectFildes;
 {
 	addressType		 startAddress;
-	reservationListType	*buildReservation();
 
 	if (debug)
 		printf("	reservations\n");
diff --git a/slinky/read.h b/slinky/read.h
new file mode 100644
index 0000000..a88557a
--- /dev/null
+++ b/slinky/read.h
@@ -0,0 +1,28 @@
+#ifndef READ_H_
+#define READ_H_
+
+#include "slinkyTypes.h"
+
+void fileCheck(FILE *fildes, char *fileName);
+wordType readWord(FILE *file, char *fileName);
+byte readByte(FILE *file, char *fileName);
+bigWord readBigword(FILE *file, char *fileName);
+bigWord read3ByteWord(FILE *file, char *fileName);
+int readString(char *buffer, FILE *fildes, char *fileName);
+void readChunk(byte *buffer, int numberOfBytes, FILE *fildes, char *fileName);
+void readCode(addressType startAddress, addressType endAddress, int mode, objectFileListType *objectFile, FILE *objectFildes);
+bool compareReferences(expressionReferenceType *reference1, expressionReferenceType *reference2);
+void sortReferences(expressionReferenceType *theReferences, int numberOfReferences);
+void readReference(expressionReferenceType *reference, FILE *fildes, char *fileName);
+void readReferences(objectFileListType *objectFile, FILE *objectFildes);
+bool compareSymbolValues(symbolType **symbol1, symbolType **symbol2);
+void readSymbols(objectFileListType *objectFile, FILE *objectFildes);
+expressionPCType readOneExpression(objectFileListType *objectFile, FILE *objectFildes);
+void readExpressions(objectFileListType *objectFile, FILE *objectFildes);
+argumentListType *readArgumentList(objectFileListType *objectFile, FILE *objectFildes);
+void readFunctions(objectFileListType *objectFile, FILE *objectFildes);
+void instantiateExpressionAndSymbolPointers(objectFileListType *objectFile);
+void readReservations(objectFileListType *objectFile, FILE *objectFildes);
+reservationListType *buildReservation(addressType startAddress, int blockSize, reservationListType *nextReservation);
+
+#endif
diff --git a/slinky/relocate.c b/slinky/relocate.c
index c04f95b..a108d8a 100644
--- a/slinky/relocate.c
+++ b/slinky/relocate.c
@@ -30,6 +30,11 @@
 
 #include "slinkyTypes.h"
 #include "slinkyGlobals.h"
+#include "relocate.h"
+#include "debugPrint.h"
+#include "errorStuff.h"
+#include "link.h"
+#include "map.h"
 
 #define isUndefined(symbol) (((symbol)->symbolClass & ~SYMBOL_EXTERNAL) == 0)
 
diff --git a/slinky/relocate.h b/slinky/relocate.h
new file mode 100644
index 0000000..ebdcf9f
--- /dev/null
+++ b/slinky/relocate.h
@@ -0,0 +1,22 @@
+#ifndef RELOCATE_H_
+#define RELOCATE_H_
+
+#include "slinkyTypes.h"
+
+void removeZeroPageFromFreeList(void);
+addressType align(addressType address, int alignment);
+addressType constrain(addressType address, int size, addressType constraint);
+void moveRelocationBase(addressType newBase);
+addressType allocateRelocatable(codeSegmentHeaderType *codeSegment);
+void relocateOneCodeSegment(codeSegmentHeaderType *codeSegment, addressType targetLocation);
+void relocatem(void);
+codeSegmentHeaderType *matchModes(symbolType *symbol, codeSegmentHeaderType *codeSegment);
+bool matchedModes(symbolType *symbol, codeSegmentHeaderType *codeSegment);
+codeSegmentHeaderType *synchronizeCodeSegment(symbolType *symbol, codeSegmentHeaderType *codeSegment);
+void handleGlobalSymbol(symbolType *symbol);
+void valueSymbol(symbolType *symbol, codeSegmentHeaderType *codeSegment);
+symbolType *lookupGlobalSymbol(char *symbolName);
+void valueUndefinedSymbol(symbolType *symbol);
+void valuem(void);
+
+#endif
diff --git a/slinky/slinkyTables.c b/slinky/slinkyTables.c
index d4ecc71..6146fb5 100644
--- a/slinky/slinkyTables.c
+++ b/slinky/slinkyTables.c
@@ -28,23 +28,7 @@
 */
 
 #include "slinkyTypes.h"
-
-addressType	atasciiBIF();
-addressType	atasciiColorBIF();
-addressType	isAbsoluteValueBIF();
-addressType	isConditionCodeBIF();
-addressType	isDefinedBIF();
-addressType	isExternalBIF();
-addressType	nthCharBIF();
-addressType	printfBIF();
-addressType	strcatBIF();
-addressType	strcmpBIF();
-addressType	strcmplcBIF();
-addressType	strlenBIF();
-addressType	substrBIF();
-addressType	symbolDefineBIF();
-addressType	symbolLookupBIF();
-addressType	symbolNameBIF();
+#include "builtins.h"
 
 /* Used to initialize symbols representing built-in functions */
 struct {
diff --git a/slinky/slinkyTables.h b/slinky/slinkyTables.h
new file mode 100644
index 0000000..30ca7e3
--- /dev/null
+++ b/slinky/slinkyTables.h
@@ -0,0 +1,7 @@
+#ifndef SLINKY_TABLES_H_
+#define SLINKY_TABLES_H_
+
+#include "slinkyTypes.h"
+
+
+#endif
diff --git a/slinky/slinkyTypes.h b/slinky/slinkyTypes.h
index 2f41f51..161a143 100644
--- a/slinky/slinkyTypes.h
+++ b/slinky/slinkyTypes.h
@@ -26,6 +26,8 @@
 
 	8-March-1985
 */
+#ifndef SLINKY_TYPES_H_
+#define SLINKY_TYPES_H_
 
 #include <stdlib.h>
 #include <stdio.h>
@@ -188,3 +190,5 @@ typedef enum {
 
 #define typeAlloc(type) 		(type *)malloc(sizeof(type))
 #define typeAllocBlock(type, size)	(type *)malloc(sizeof(type) * (size))
+
+#endif
diff --git a/slinky/write.c b/slinky/write.c
index b73b8e9..740e923 100644
--- a/slinky/write.c
+++ b/slinky/write.c
@@ -30,6 +30,7 @@
 
 #include "slinkyTypes.h"
 #include "slinkyGlobals.h"
+#include "write.h"
 
 #define writeWord(aWord) putc(aWord & 0xFF, loadFileOutput);\
 			putc((aWord >> 8) & 0xFF, loadFileOutput)
diff --git a/slinky/write.h b/slinky/write.h
new file mode 100644
index 0000000..e4b616c
--- /dev/null
+++ b/slinky/write.h
@@ -0,0 +1,10 @@
+#ifndef WRITE_H_
+#define WRITE_H_
+
+#include "slinkyTypes.h"
+
+void writeEntryPoint(void);
+void writeCodeSegment(codeSegmentHeaderType *codeSegment);
+void writem(void);
+
+#endif