diff --git a/sourcepawn/include/sp_file_headers.h b/sourcepawn/include/sp_file_headers.h
index c7bd81ae..b83fff38 100644
--- a/sourcepawn/include/sp_file_headers.h
+++ b/sourcepawn/include/sp_file_headers.h
@@ -52,7 +52,7 @@ typedef struct sp_file_hdr_s
 	uint32_t	disksize;	/* size on disk */
 	uint32_t	imagesize;	/* size in memory */
 	uint8_t		sections;	/* number of sections */
-	uint32_t	stringtab;	/* offset to string table aa*/
+	uint32_t	stringtab;	/* offset to string table */
 	uint32_t	dataoffs;	/* offset to file proper (any compression starts here) */
 } sp_file_hdr_t;
 
diff --git a/sourcepawn/include/sp_vm_types.h b/sourcepawn/include/sp_vm_types.h
index 52019b07..9569b924 100644
--- a/sourcepawn/include/sp_vm_types.h
+++ b/sourcepawn/include/sp_vm_types.h
@@ -12,6 +12,9 @@ typedef int32_t		cell_t;
 #define SP_ERR_NONE					0
 #define SP_ERR_FILE_FORMAT			1	/* File format unrecognized */
 #define SP_ERR_DECOMPRESSOR			2	/* A decompressor was not found */
+#define SP_ERR_HEAPLOW				3	/* Not enough space left on the heap */
+#define SP_ERR_PARAM				4	/* Invalid parameter */
+#define SP_ERR_INVALID_ADDRESS		5	/* A memory address was not valid */
 
 /**********************************************
  *** The following structures are reference structures.
@@ -183,9 +186,10 @@ typedef struct sp_context_s
 	SPVM_EXEC		exec;		/* execution base */
 	cell_t			pri;		/* PRI register */
 	cell_t			alt;		/* ALT register */
-	cell_t			*data;		/* data chunk */
-	cell_t			*heap;		/* pointer after data for start of heap */
-	cell_t			*sp;		/* stack pointer */
+	uint8_t			*data;		/* data chunk */
+	cell_t			heapbase;	/* heap base */
+	cell_t			hp;			/* heap pointer */
+	cell_t			sp;			/* stack pointer */
 	ucell_t			memory;		/* total memory size; */
 	int32_t			err;		/* error code */
 	uint32_t		pushcount;	/* push count */
diff --git a/sourcepawn/vm/msvc8/vm.vcproj b/sourcepawn/vm/msvc8/vm.vcproj
index c7aaedd7..66fe7b10 100644
--- a/sourcepawn/vm/msvc8/vm.vcproj
+++ b/sourcepawn/vm/msvc8/vm.vcproj
@@ -41,13 +41,13 @@
 				Name="VCCLCompilerTool"
 				Optimization="0"
 				AdditionalIncludeDirectories="..\..\include"
-				PreprocessorDefinitions="WIN32;_DEBUG;_CONSOLE"
+				PreprocessorDefinitions="WIN32;_DEBUG;_CONSOLE;_CRT_SECURE_NO_DEPRECATE"
 				MinimalRebuild="true"
 				BasicRuntimeChecks="3"
 				RuntimeLibrary="3"
 				UsePrecompiledHeader="0"
 				WarningLevel="3"
-				Detect64BitPortabilityProblems="true"
+				Detect64BitPortabilityProblems="false"
 				DebugInformationFormat="4"
 			/>
 			<Tool
@@ -176,7 +176,7 @@
 			UniqueIdentifier="{4FC737F1-C7A5-4376-A066-2A32D752A2FF}"
 			>
 			<File
-				RelativePath="..\test.c"
+				RelativePath="..\sp_vm.c"
 				>
 			</File>
 		</Filter>
diff --git a/sourcepawn/vm/sp_vm.c b/sourcepawn/vm/sp_vm.c
new file mode 100644
index 00000000..2c668530
--- /dev/null
+++ b/sourcepawn/vm/sp_vm.c
@@ -0,0 +1,107 @@
+#include <limits.h>
+#include <assert.h>
+#include "sp_vm.h"
+
+#define CELLBOUNDMAX	(INT_MAX/sizeof(cell_t))
+#define STACKMARGIN		((cell_t)(16*sizeof(cell_t)))
+
+int main()
+{
+	/** temporary testing area */
+	sp_context_t ctx;
+	cell_t l, *p;
+
+	ctx.data = (uint8_t *)malloc(50000);
+	ctx.memory = 50000;
+	ctx.heapbase = 200;
+	ctx.hp = ctx.heapbase;
+	ctx.sp = 45000;
+
+	assert(SP_HeapAlloc(&ctx, 500, &l, &p) == SP_ERR_NONE);
+	assert(SP_HeapPop(&ctx, l) == SP_ERR_NONE);
+	assert(SP_HeapRelease(&ctx, l) == SP_ERR_NONE);
+	assert(SP_HeapRelease(&ctx, 4) == SP_ERR_INVALID_ADDRESS);
+	assert(SP_HeapAlloc(&ctx, 500, &l, &p) == SP_ERR_NONE);
+	assert(SP_HeapRelease(&ctx, l) == SP_ERR_NONE);
+
+	return 0;
+}
+
+int SP_HeapAlloc(sp_context_t *ctx, unsigned int cells, cell_t *local_addr, cell_t **phys_addr)
+{
+	cell_t *addr;
+	ucell_t realmem;
+
+#if 0
+	if (cells > CELLBOUNDMAX)
+	{
+		return SP_ERR_PARAM;
+	}
+#else
+	assert(cells < CELLBOUNDMAX);
+#endif
+
+	realmem = cells * sizeof(cell_t);
+
+	/**
+	 * Check if the space between the heap and stack is sufficient.
+	 */
+	if ((cell_t)(ctx->sp - ctx->hp - realmem) < STACKMARGIN)
+	{
+		return SP_ERR_HEAPLOW;
+	}
+
+	addr = (cell_t *)(ctx->data + ctx->hp);
+	/* store size of allocation in cells */
+	*addr = (cell_t)cells;
+	addr++;
+	ctx->hp += sizeof(cell_t);
+
+	*local_addr = ctx->hp;
+
+	if (phys_addr)
+	{
+		*phys_addr = addr;
+	}
+
+	ctx->hp += realmem;
+
+	return SP_ERR_NONE;
+}
+
+int SP_HeapPop(sp_context_t *ctx, cell_t local_addr)
+{
+	cell_t cellcount;
+	cell_t *addr;
+
+	/* check the bounds of this address */
+	local_addr -= sizeof(cell_t);
+	if (local_addr < ctx->heapbase || local_addr >= ctx->sp)
+	{
+		return SP_ERR_INVALID_ADDRESS;
+	}
+
+	addr = (cell_t *)(ctx->data + local_addr);
+	cellcount = (*addr) * sizeof(cell_t);
+	/* check if this memory count looks valid */
+	if (ctx->hp - cellcount - sizeof(cell_t) != local_addr)
+	{
+		return SP_ERR_INVALID_ADDRESS;
+	}
+
+	ctx->hp = local_addr;
+
+	return SP_ERR_NONE;
+}
+
+int SP_HeapRelease(sp_context_t *ctx, cell_t local_addr)
+{
+	if (local_addr < ctx->heapbase)
+	{
+		return SP_ERR_INVALID_ADDRESS;
+	}
+
+	ctx->hp = local_addr - sizeof(cell_t);
+
+	return SP_ERR_NONE;
+}