diff --git a/pom.xml b/pom.xml
index dfb330e6d2..da15c52446 100644
--- a/pom.xml
+++ b/pom.xml
@@ -14,6 +14,17 @@
 			<artifactId>guava</artifactId>
 			<version>18.0</version>
 		</dependency>
+		<dependency>
+			<groupId>org.slf4j</groupId>
+			<artifactId>slf4j-api</artifactId>
+			<version>1.7.12</version>
+		</dependency>
+		<dependency>
+			<groupId>org.slf4j</groupId>
+			<artifactId>slf4j-simple</artifactId>
+			<version>1.7.12</version>
+			<scope>test</scope>
+		</dependency>
 		<dependency>
 			<groupId>junit</groupId>
 			<artifactId>junit</artifactId>
diff --git a/src/main/java/net/runelite/cache/fs/DataFile.java b/src/main/java/net/runelite/cache/fs/DataFile.java
new file mode 100644
index 0000000000..384b7b2008
--- /dev/null
+++ b/src/main/java/net/runelite/cache/fs/DataFile.java
@@ -0,0 +1,203 @@
+package net.runelite.cache.fs;
+
+import java.io.Closeable;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.nio.ByteBuffer;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class DataFile implements Closeable
+{
+	private static final Logger logger = LoggerFactory.getLogger(DataFile.class);
+	
+	private static final long SECTOR_SIZE = 520L;
+	
+	private final int datafileId;
+	private final RandomAccessFile dat;
+	private final byte[] readCachedBuffer = new byte[520];
+	
+	public DataFile(int id, File file) throws FileNotFoundException
+	{
+		this.datafileId = id;
+		dat = new RandomAccessFile(file, "rw");
+	}
+	
+	@Override
+	public void close() throws IOException
+	{
+		dat.close();
+	}
+	
+	public synchronized ByteBuffer read(int archiveId, int sector, int size) throws IOException
+	{
+		if (sector <= 0L || dat.length() / 520L < (long) sector)
+		{
+			logger.warn("bad read, dat length {}", dat.length());
+			return null;
+		}
+		
+		ByteBuffer buffer = ByteBuffer.allocate(size);
+		
+		dat.seek(SECTOR_SIZE * (long) sector);
+		
+		for (int part = 0, readBytesCount = 0, nextSector;
+			size > readBytesCount;
+			sector = nextSector)
+		{
+			if (sector == 0)
+			{
+				return null;
+			}
+
+			dat.seek(SECTOR_SIZE * sector);
+			int dataBlockSize = size - readBytesCount;
+			byte headerSize;
+			int currentIndex;
+			int currentPart;
+			int currentArchive;
+			if (0xFFFF < archiveId)
+			{
+				headerSize = 10;
+				if (dataBlockSize > 510)
+				{
+					dataBlockSize = 510;
+				}
+
+				int i = dat.read(this.readCachedBuffer, 0, headerSize + dataBlockSize);
+				if (i != headerSize + dataBlockSize)
+				{
+					logger.warn("short read");
+					return null;
+				}
+				currentArchive = ((this.readCachedBuffer[1] & 255) << 16) + ((this.readCachedBuffer[0] & 255) << 24) + (('\uff00' & this.readCachedBuffer[2] << 8) - -(this.readCachedBuffer[3] & 255));
+				currentPart = ((this.readCachedBuffer[4] & 255) << 8) + (255 & this.readCachedBuffer[5]);
+				nextSector = (this.readCachedBuffer[8] & 255) + ('\uff00' & this.readCachedBuffer[7] << 8) + ((255 & this.readCachedBuffer[6]) << 16);
+				currentIndex = this.readCachedBuffer[9] & 255;
+			}
+			else
+			{
+				headerSize = 8;
+				if (dataBlockSize > 512)
+				{
+					dataBlockSize = 512;
+				}
+
+				int i = dat.read(this.readCachedBuffer, 0, headerSize + dataBlockSize);
+				if (i != headerSize + dataBlockSize)
+				{
+					logger.warn("short read");
+					return null;
+				}
+				currentArchive = (255 & this.readCachedBuffer[1]) + ('\uff00' & this.readCachedBuffer[0] << 8);
+				currentPart = ((this.readCachedBuffer[2] & 255) << 8) + (255 & this.readCachedBuffer[3]);
+				nextSector = (this.readCachedBuffer[6] & 255) + ('\uff00' & this.readCachedBuffer[5] << 8) + ((255 & this.readCachedBuffer[4]) << 16);
+				currentIndex = this.readCachedBuffer[7] & 255;
+			}
+
+			if (archiveId != currentArchive || currentPart != part || this.datafileId != currentIndex)
+			{
+				return null;
+			}
+
+			if (nextSector < 0 || dat.length() / 520L < (long) nextSector)
+			{
+				return null;
+			}
+
+			buffer.put(readCachedBuffer, headerSize, dataBlockSize);
+			readBytesCount += dataBlockSize;
+
+			++part;
+		}
+
+		return buffer;
+	}
+	
+	public synchronized int write(int archiveId, ByteBuffer data) throws IOException
+	{
+		int e;
+		int startSector;
+		
+		e = (int) ((this.dat.length() + 519L) / 520L);
+		if (e == 0)
+		{
+			e = 1;
+		}
+		startSector = e;
+
+		for (int part = 0; data.hasRemaining(); ++part)
+		{
+			int nextSector = 0;
+			int dataToWrite;
+
+			if (nextSector == 0)
+			{
+				nextSector = (int) ((dat.length() + 519L) / 520L);
+				if (nextSector == 0)
+				{
+					++nextSector;
+				}
+
+				if (nextSector == e)
+				{
+					++nextSector;
+				}
+			}
+
+			if (data.remaining() <= 512)
+			{
+				nextSector = 0;
+			}
+
+			if (0xFFFF < archiveId)
+			{
+				this.readCachedBuffer[0] = (byte) (archiveId >> 24);
+				this.readCachedBuffer[1] = (byte) (archiveId >> 16);
+				this.readCachedBuffer[2] = (byte) (archiveId >> 8);
+				this.readCachedBuffer[3] = (byte) archiveId;
+				this.readCachedBuffer[4] = (byte) (part >> 8);
+				this.readCachedBuffer[5] = (byte) part;
+				this.readCachedBuffer[6] = (byte) (nextSector >> 16);
+				this.readCachedBuffer[7] = (byte) (nextSector >> 8);
+				this.readCachedBuffer[8] = (byte) nextSector;
+				this.readCachedBuffer[9] = (byte) this.datafileId;
+				dat.seek(SECTOR_SIZE * (long) e);
+				dat.write(this.readCachedBuffer, 0, 10);
+				
+				dataToWrite = data.remaining();
+				if (dataToWrite > 510)
+				{
+					dataToWrite = 510;
+				}
+			}
+			else
+			{
+				this.readCachedBuffer[0] = (byte) (archiveId >> 8);
+				this.readCachedBuffer[1] = (byte) archiveId;
+				this.readCachedBuffer[2] = (byte) (part >> 8);
+				this.readCachedBuffer[3] = (byte) part;
+				this.readCachedBuffer[4] = (byte) (nextSector >> 16);
+				this.readCachedBuffer[5] = (byte) (nextSector >> 8);
+				this.readCachedBuffer[6] = (byte) nextSector;
+				this.readCachedBuffer[7] = (byte) this.datafileId;
+				dat.seek(SECTOR_SIZE * (long) e);
+				dat.write(this.readCachedBuffer, 0, 8);
+				
+				dataToWrite = data.remaining();
+				if (dataToWrite > 512)
+				{
+					dataToWrite = 512;
+				}
+			}
+
+			data.get(readCachedBuffer, 0, dataToWrite);
+			dat.write(readCachedBuffer, 0, dataToWrite);
+			e = nextSector;
+		}
+		
+		return startSector;
+	}
+}
diff --git a/src/test/java/net/runelite/cache/fs/DataFileTest.java b/src/test/java/net/runelite/cache/fs/DataFileTest.java
new file mode 100644
index 0000000000..e8d011e367
--- /dev/null
+++ b/src/test/java/net/runelite/cache/fs/DataFileTest.java
@@ -0,0 +1,36 @@
+package net.runelite.cache.fs;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class DataFileTest
+{
+	@Test
+	public void test1() throws IOException
+	{
+		File file = new File("d:/rs/07/test/test.dat");
+		DataFile df = new DataFile(42, file);
+		int sector = df.write(3, ByteBuffer.wrap("test".getBytes()));
+		ByteBuffer buf = df.read(3, sector, 4);
+		String str = new String(buf.array());
+		Assert.assertEquals("test", str);
+		file.delete();
+	}
+	
+	@Test
+	public void test2() throws IOException
+	{
+		byte[] b = new byte[1024];
+		for (int i = 0; i < 1024; ++i) b[i] = (byte) i;
+		
+		File file = new File("d:/rs/07/test/test.dat");
+		DataFile df = new DataFile(42, file);
+		int sector = df.write(0x1FFFF, ByteBuffer.wrap(b));
+		ByteBuffer buf = df.read(0x1FFFF, sector, b.length);
+		Assert.assertArrayEquals(b, buf.array());
+		file.delete();
+	}
+}