diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3d5801063..c12606ca0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,10 +21,11 @@ file(GLOB GBA_SV_SRC ${CMAKE_SOURCE_DIR}/src/gba/supervisor/*.c)
 file(GLOB UTIL_SRC ${CMAKE_SOURCE_DIR}/src/util/*.[cSs])
 file(GLOB VFS_SRC ${CMAKE_SOURCE_DIR}/src/util/vfs/*.c)
 file(GLOB RENDERER_SRC ${CMAKE_SOURCE_DIR}/src/gba/renderers/video-software.c)
+file(GLOB SIO_SRC ${CMAKE_SOURCE_DIR}/src/gba/sio/*.c)
 file(GLOB THIRD_PARTY_SRC ${CMAKE_SOURCE_DIR}/src/third-party/inih/*.c)
 list(APPEND UTIL_SRC ${CMAKE_SOURCE_DIR}/src/platform/commandline.c)
 source_group("ARM core" FILES ${ARM_SRC})
-source_group("GBA board" FILES ${GBA_SRC} ${RENDERER_SRC})
+source_group("GBA board" FILES ${GBA_SRC} ${RENDERER_SRC} ${SIO_SRC})
 source_group("GBA supervisor" FILES ${GBA_SV_SRC})
 source_group("Utilities" FILES ${UTIL_SRC} ${VFS_SRC}})
 include_directories(${CMAKE_SOURCE_DIR}/src/arm)
@@ -275,6 +276,7 @@ set(SRC
 	${GBA_SV_SRC}
 	${DEBUGGER_SRC}
 	${RENDERER_SRC}
+	${SIO_SRC}
 	${UTIL_SRC}
 	${VFS_SRC}
 	${OS_SRC}
diff --git a/src/gba/io.c b/src/gba/io.c
index 5ee548cb1..8995ae7da 100644
--- a/src/gba/io.c
+++ b/src/gba/io.c
@@ -604,6 +604,10 @@ uint16_t GBAIORead(struct GBA* gba, uint32_t address) {
 		return gba->sio.siocnt;
 	case REG_RCNT:
 		return gba->sio.rcnt;
+	case REG_JOY_RECV_LO:
+	case REG_JOY_RECV_HI:
+		gba->memory.io[REG_JOYSTAT >> 1] &= ~2;
+		break;
 
 	case REG_DMA0CNT_LO:
 	case REG_DMA1CNT_LO:
@@ -644,8 +648,6 @@ uint16_t GBAIORead(struct GBA* gba, uint32_t address) {
 	case REG_SIOMULTI3:
 	case REG_SIOMLT_SEND:
 	case REG_JOYCNT:
-	case REG_JOY_RECV_LO:
-	case REG_JOY_RECV_HI:
 	case REG_JOY_TRANS_LO:
 	case REG_JOY_TRANS_HI:
 	case REG_JOYSTAT:
diff --git a/src/gba/sio/dolphin.c b/src/gba/sio/dolphin.c
new file mode 100644
index 000000000..51afb1b76
--- /dev/null
+++ b/src/gba/sio/dolphin.c
@@ -0,0 +1,170 @@
+/* Copyright (c) 2013-2015 Jeffrey Pfau
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include "dolphin.h"
+
+#include "gba/io.h"
+
+#define CLOCK_GRAIN 2048
+#define CYCLES_PER_BIT 75
+
+const uint16_t DOLPHIN_CLOCK_PORT = 49420;
+const uint16_t DOLPHIN_DATA_PORT = 54970;
+
+enum {
+	CMD_RESET = 0xFF,
+	CMD_POLL = 0x00,
+	CMD_TRANS = 0x14,
+	CMD_RECV = 0x15,
+};
+
+// static bool GBASIODolphinInit(struct GBASIODriver* driver);
+// static void GBASIODolphinDeinit(struct GBASIODriver* driver);
+static bool GBASIODolphinLoad(struct GBASIODriver* driver);
+// static bool GBASIODolphinUnload(struct GBASIODriver* driver);
+static uint16_t GBASIODolphinWriteRegister(struct GBASIODriver* driver, uint32_t address, uint16_t value);
+static int32_t GBASIODolphinProcessEvents(struct GBASIODriver* driver, int32_t cycles);
+
+void GBASIODolphinCreate(struct GBASIODolphin* dol) {
+	dol->d.init = 0;
+	dol->d.deinit = 0;
+	dol->d.load = GBASIODolphinLoad;
+	dol->d.unload = 0;
+	dol->d.writeRegister = GBASIODolphinWriteRegister;
+	dol->d.processEvents = GBASIODolphinProcessEvents;
+
+	dol->data = INVALID_SOCKET;
+	dol->clock = INVALID_SOCKET;
+}
+
+void GBASIODolphinDestroy(struct GBASIODolphin* dol) {
+	if (!SOCKET_FAILED(dol->data)) {
+		SocketClose(dol->data);
+		dol->data = INVALID_SOCKET;
+	}
+
+	if (!SOCKET_FAILED(dol->clock)) {
+		SocketClose(dol->clock);
+		dol->clock = INVALID_SOCKET;
+	}
+}
+
+bool GBASIODolphinConnect(struct GBASIODolphin* dol, const struct Address* address, short dataPort, short clockPort) {
+	if (!SOCKET_FAILED(dol->data)) {
+		SocketClose(dol->data);
+		dol->data = INVALID_SOCKET;
+	}
+	if (!dataPort) {
+		dataPort = DOLPHIN_DATA_PORT;
+	}
+
+	if (!SOCKET_FAILED(dol->clock)) {
+		SocketClose(dol->clock);
+		dol->clock = INVALID_SOCKET;
+	}
+	if (!clockPort) {
+		clockPort = DOLPHIN_CLOCK_PORT;
+	}
+
+	dol->data = SocketConnectTCP(dataPort, address);
+	if (SOCKET_FAILED(dol->data)) {
+		return false;
+	}
+
+	dol->clock = SocketConnectTCP(clockPort, address);
+	if (SOCKET_FAILED(dol->clock)) {
+		SocketClose(dol->clock);
+		return false;
+	}
+
+	SocketSetBlocking(dol->data, false);
+	SocketSetBlocking(dol->clock, false);
+	return true;
+}
+
+static bool GBASIODolphinLoad(struct GBASIODriver* driver) {
+	struct GBASIODolphin* dol = (struct GBASIODolphin*) driver;
+	dol->nextEvent = 0;
+	return true;
+}
+
+uint16_t GBASIODolphinWriteRegister(struct GBASIODriver* driver, uint32_t address, uint16_t value) {
+	struct GBASIODolphin* dol = (struct GBASIODolphin*) driver;
+	switch (address) {
+	case REG_JOYCNT:
+		return (value & 0x0040) | (dol->d.p->p->memory.io[REG_JOYCNT >> 1] & ~(value & 0x7) & ~0x0040);
+	case REG_JOYSTAT:
+		return (value & 0x0030) | (dol->d.p->p->memory.io[REG_JOYSTAT >> 1] & ~0x30);
+	case REG_JOY_TRANS_LO:
+	case REG_JOY_TRANS_HI:
+		dol->d.p->p->memory.io[REG_JOYSTAT >> 1] |= 8;
+		break;
+	}
+	return value;
+}
+
+int32_t GBASIODolphinProcessEvents(struct GBASIODriver* driver, int32_t cycles) {
+	struct GBASIODolphin* dol = (struct GBASIODolphin*) driver;
+	dol->nextEvent -= cycles;
+	if (dol->nextEvent <= 0) {
+		uint8_t command;
+		int32_t nextEvent = CLOCK_GRAIN;
+		uint32_t clocks = 0;
+		uint32_t clockSlice;
+		while (SocketRecv(dol->clock, &clockSlice, 4) == 4) {
+			clocks += ntohl(clockSlice);
+		}
+		while (SocketRecv(dol->data, &command, 1) == 1) {
+			int bitsOnLine = 8 + 1;
+			uint8_t buffer[5];
+
+			switch (command) {
+			case CMD_RESET:
+				dol->d.p->p->memory.io[REG_JOYCNT >> 1] |= 1;
+				if (dol->d.p->p->memory.io[REG_JOYCNT >> 1] & 0x40) {
+					GBARaiseIRQ(dol->d.p->p, IRQ_SIO);
+				}
+				// Fall through
+			case CMD_POLL:
+				buffer[0] = 0x00;
+				buffer[1] = 0x04;
+				buffer[2] = dol->d.p->p->memory.io[REG_JOYSTAT >> 1];
+				SocketSend(dol->data, buffer, 3);
+				bitsOnLine += 24 + 1;
+				break;
+			case CMD_RECV:
+				dol->d.p->p->memory.io[REG_JOYCNT >> 1] |= 2;
+				dol->d.p->p->memory.io[REG_JOYSTAT >> 1] |= 2;
+				SocketRecv(dol->data, &buffer, 4);
+				dol->d.p->p->memory.io[REG_JOY_RECV_LO >> 1] = buffer[0] | (buffer[1] << 8);
+				dol->d.p->p->memory.io[REG_JOY_RECV_HI >> 1] = buffer[2] | (buffer[3] << 8);
+				buffer[0] = dol->d.p->p->memory.io[REG_JOYSTAT >> 1];
+				SocketSend(dol->data, buffer, 1);
+				if (dol->d.p->p->memory.io[REG_JOYCNT >> 1] & 0x40) {
+					GBARaiseIRQ(dol->d.p->p, IRQ_SIO);
+				}
+				bitsOnLine += 40 + 1;
+				break;
+			case CMD_TRANS:
+				dol->d.p->p->memory.io[REG_JOYCNT >> 1] |= 4;
+				dol->d.p->p->memory.io[REG_JOYSTAT >> 1] &= ~8;
+				buffer[0] = dol->d.p->p->memory.io[REG_JOY_TRANS_LO >> 1];
+				buffer[1] = dol->d.p->p->memory.io[REG_JOY_TRANS_LO >> 1] >> 8;
+				buffer[2] = dol->d.p->p->memory.io[REG_JOY_TRANS_HI >> 1];
+				buffer[3] = dol->d.p->p->memory.io[REG_JOY_TRANS_HI >> 1] >> 8;
+				buffer[4] = dol->d.p->p->memory.io[REG_JOYSTAT >> 1];
+				SocketSend(dol->data, buffer, 5);
+				if (dol->d.p->p->memory.io[REG_JOYCNT >> 1] & 0x40) {
+					GBARaiseIRQ(dol->d.p->p, IRQ_SIO);
+				}
+				bitsOnLine += 40 + 1;
+				break;
+			}
+			nextEvent = bitsOnLine * CYCLES_PER_BIT;
+		}
+		dol->nextEvent += nextEvent;
+	}
+	return dol->nextEvent;
+}
diff --git a/src/gba/sio/dolphin.h b/src/gba/sio/dolphin.h
new file mode 100644
index 000000000..2ba4e53b6
--- /dev/null
+++ b/src/gba/sio/dolphin.h
@@ -0,0 +1,30 @@
+/* Copyright (c) 2013-2015 Jeffrey Pfau
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef SIO_LOCKSTEP_H
+#define SIO_LOCKSTEP_H
+
+#include "gba/sio.h"
+
+#include "util/socket.h"
+
+extern const uint16_t DOLPHIN_CLOCK_PORT;
+extern const uint16_t DOLPHIN_DATA_PORT;
+
+struct GBASIODolphin {
+	struct GBASIODriver d;
+
+	Socket data;
+	Socket clock;
+
+	int32_t nextEvent;
+};
+
+void GBASIODolphinCreate(struct GBASIODolphin*);
+void GBASIODolphinDestroy(struct GBASIODolphin*);
+
+bool GBASIODolphinConnect(struct GBASIODolphin*, const struct Address* address, short dataPort, short clockPort);
+
+#endif