diff --git a/higan/emulator/emulator.hpp b/higan/emulator/emulator.hpp
index c143f4c1..6e403b74 100644
--- a/higan/emulator/emulator.hpp
+++ b/higan/emulator/emulator.hpp
@@ -6,7 +6,7 @@ using namespace nall;
 
 namespace Emulator {
   static const string Name = "higan";
-  static const string Version = "097.30";
+  static const string Version = "097.31";
   static const string Author = "byuu";
   static const string License = "GPLv3";
   static const string Website = "http://byuu.org/";
diff --git a/higan/sfc/GNUmakefile b/higan/sfc/GNUmakefile
index 4aa55e3e..ef037d72 100644
--- a/higan/sfc/GNUmakefile
+++ b/higan/sfc/GNUmakefile
@@ -3,7 +3,8 @@ processors += r65816 spc700 arm gsu hg51b upd96050
 objects += sfc-interface sfc-system sfc-scheduler sfc-controller
 objects += sfc-cartridge sfc-cheat
 objects += sfc-memory sfc-cpu sfc-smp sfc-dsp sfc-ppu
-objects += sfc-satellaview sfc-superdisc sfc-eboot
+objects += sfc-satellaview sfc-superdisc
+objects += sfc-21fx
 objects += sfc-icd2 sfc-mcc sfc-nss sfc-event
 objects += sfc-sa1 sfc-superfx
 objects += sfc-armdsp sfc-hitachidsp sfc-necdsp
@@ -48,7 +49,7 @@ obj/sfc-ppu.o:         sfc/$(sfcppu)/ppu.cpp $(call rwildcard,sfc/$(sfcppu)/)
 
 obj/sfc-satellaview.o: sfc/expansion/satellaview/satellaview.cpp $(call rwildcard,sfc/expansion/satellaview/)
 obj/sfc-superdisc.o:   sfc/expansion/superdisc/superdisc.cpp $(call rwildcard,sfc/expansion/superdisc/)
-obj/sfc-eboot.o:       sfc/expansion/eboot/eboot.cpp $(call rwildcard,sfc/expansion/eboot/)
+obj/sfc-21fx.o:        sfc/expansion/21fx/21fx.cpp $(call rwildcard,sfc/expansion/21fx/)
 
 obj/sfc-icd2.o:        sfc/coprocessor/icd2/icd2.cpp $(call rwildcard,sfc/coprocessor/icd2/)
 obj/sfc-mcc.o:         sfc/coprocessor/mcc/mcc.cpp $(call rwildcard,sfc/coprocessor/mcc/)
diff --git a/higan/sfc/dsp/brr.cpp b/higan/sfc/dsp/brr.cpp
index 71dd0901..710d10f3 100644
--- a/higan/sfc/dsp/brr.cpp
+++ b/higan/sfc/dsp/brr.cpp
@@ -1,15 +1,15 @@
 auto DSP::brrDecode(Voice& v) -> void {
   //state.t_brr_byte = ram[v.brr_addr + v.brr_offset] cached from previous clock cycle
-  signed nybbles = (state._brrByte << 8) + smp.apuram[(uint16)(v.brrAddress + v.brrOffset + 1)];
+  int nybbles = (state._brrByte << 8) + smp.apuram[(uint16)(v.brrAddress + v.brrOffset + 1)];
 
-  const signed filter = (state._brrHeader >> 2) & 3;
-  const signed scale  = (state._brrHeader >> 4);
+  const int filter = (state._brrHeader >> 2) & 3;
+  const int scale  = (state._brrHeader >> 4);
 
   //decode four samples
   for(auto n : range(4)) {
     //bits 12-15 = current nybble; sign extend, then shift right to 4-bit precision
     //result: s = 4-bit sign-extended sample value
-    signed s = (int16)nybbles >> 12;
+    int s = (int16)nybbles >> 12;
     nybbles <<= 4; //slide nybble so that on next loop iteration, bits 12-15 = current nybble
 
     if(scale <= 12) {
@@ -20,8 +20,8 @@ auto DSP::brrDecode(Voice& v) -> void {
     }
 
     //apply IIR filter (2 is the most commonly used)
-    const signed p1 = v.buffer[v.bufferOffset - 1];
-    const signed p2 = v.buffer[v.bufferOffset - 2] >> 1;
+    const int p1 = v.buffer[v.bufferOffset - 1];
+    const int p2 = v.buffer[v.bufferOffset - 2] >> 1;
 
     switch(filter) {
     case 0:
diff --git a/higan/sfc/dsp/counter.cpp b/higan/sfc/dsp/counter.cpp
index 42edcbe0..4a2a7537 100644
--- a/higan/sfc/dsp/counter.cpp
+++ b/higan/sfc/dsp/counter.cpp
@@ -42,7 +42,7 @@ inline auto DSP::counterTick() -> void {
 
 //return true if counter event should trigger
 
-inline auto DSP::counterPoll(unsigned rate) -> bool {
+inline auto DSP::counterPoll(uint rate) -> bool {
   if(rate == 0) return false;
-  return (((unsigned)state.counter + CounterOffset[rate]) % CounterRate[rate]) == 0;
+  return (((uint)state.counter + CounterOffset[rate]) % CounterRate[rate]) == 0;
 }
diff --git a/higan/sfc/dsp/echo.cpp b/higan/sfc/dsp/echo.cpp
index 51ce14ba..8630edfc 100644
--- a/higan/sfc/dsp/echo.cpp
+++ b/higan/sfc/dsp/echo.cpp
@@ -1,26 +1,26 @@
-auto DSP::calculateFIR(signed i, bool channel) -> signed {
-  signed s = state.echoHistory[channel][state.echoHistoryOffset + i + 1];
+auto DSP::calculateFIR(int i, bool channel) -> int {
+  int s = state.echoHistory[channel][state.echoHistoryOffset + i + 1];
   return (s * (int8)REG(FIR + i * 0x10)) >> 6;
 }
 
-auto DSP::echoOutput(bool channel) -> signed {
-  signed output = (int16)((state._mainOut[channel] * (int8)REG(MVOLL + channel * 0x10)) >> 7)
+auto DSP::echoOutput(bool channel) -> int {
+  int output = (int16)((state._mainOut[channel] * (int8)REG(MVOLL + channel * 0x10)) >> 7)
                 + (int16)((state._echoIn [channel] * (int8)REG(EVOLL + channel * 0x10)) >> 7);
   return sclamp<16>(output);
 }
 
 auto DSP::echoRead(bool channel) -> void {
-  unsigned addr = state._echoPointer + channel * 2;
+  uint addr = state._echoPointer + channel * 2;
   uint8 lo = smp.apuram[(uint16)(addr + 0)];
   uint8 hi = smp.apuram[(uint16)(addr + 1)];
-  signed s = (int16)((hi << 8) + lo);
+  int s = (int16)((hi << 8) + lo);
   state.echoHistory[channel].write(state.echoHistoryOffset, s >> 1);
 }
 
 auto DSP::echoWrite(bool channel) -> void {
   if(!(state._echoDisabled & 0x20)) {
-    unsigned addr = state._echoPointer + channel * 2;
-    signed s = state._echoOut[channel];
+    uint addr = state._echoPointer + channel * 2;
+    int s = state._echoOut[channel];
     smp.apuram[(uint16)(addr + 0)] = s;
     smp.apuram[(uint16)(addr + 1)] = s >> 8;
   }
@@ -37,16 +37,16 @@ auto DSP::echo22() -> void {
   echoRead(0);
 
   //FIR
-  signed l = calculateFIR(0, 0);
-  signed r = calculateFIR(0, 1);
+  int l = calculateFIR(0, 0);
+  int r = calculateFIR(0, 1);
 
   state._echoIn[0] = l;
   state._echoIn[1] = r;
 }
 
 auto DSP::echo23() -> void {
-  signed l = calculateFIR(1, 0) + calculateFIR(2, 0);
-  signed r = calculateFIR(1, 1) + calculateFIR(2, 1);
+  int l = calculateFIR(1, 0) + calculateFIR(2, 0);
+  int r = calculateFIR(1, 1) + calculateFIR(2, 1);
 
   state._echoIn[0] += l;
   state._echoIn[1] += r;
@@ -55,16 +55,16 @@ auto DSP::echo23() -> void {
 }
 
 auto DSP::echo24() -> void {
-  signed l = calculateFIR(3, 0) + calculateFIR(4, 0) + calculateFIR(5, 0);
-  signed r = calculateFIR(3, 1) + calculateFIR(4, 1) + calculateFIR(5, 1);
+  int l = calculateFIR(3, 0) + calculateFIR(4, 0) + calculateFIR(5, 0);
+  int r = calculateFIR(3, 1) + calculateFIR(4, 1) + calculateFIR(5, 1);
 
   state._echoIn[0] += l;
   state._echoIn[1] += r;
 }
 
 auto DSP::echo25() -> void {
-  signed l = state._echoIn[0] + calculateFIR(6, 0);
-  signed r = state._echoIn[1] + calculateFIR(6, 1);
+  int l = state._echoIn[0] + calculateFIR(6, 0);
+  int r = state._echoIn[1] + calculateFIR(6, 1);
 
   l = (int16)l;
   r = (int16)r;
@@ -82,8 +82,8 @@ auto DSP::echo26() -> void {
   state._mainOut[0] = echoOutput(0);
 
   //echo feedback
-  signed l = state._echoOut[0] + (int16)((state._echoIn[0] * (int8)REG(EFB)) >> 7);
-  signed r = state._echoOut[1] + (int16)((state._echoIn[1] * (int8)REG(EFB)) >> 7);
+  int l = state._echoOut[0] + (int16)((state._echoIn[0] * (int8)REG(EFB)) >> 7);
+  int r = state._echoOut[1] + (int16)((state._echoIn[1] * (int8)REG(EFB)) >> 7);
 
   state._echoOut[0] = sclamp<16>(l) & ~1;
   state._echoOut[1] = sclamp<16>(r) & ~1;
@@ -91,12 +91,12 @@ auto DSP::echo26() -> void {
 
 auto DSP::echo27() -> void {
   //output
-  signed outl = state._mainOut[0];
-  signed outr = echoOutput(1);
+  int outl = state._mainOut[0];
+  int outr = echoOutput(1);
   state._mainOut[0] = 0;
   state._mainOut[1] = 0;
 
-  //TODO: global muting isn't this simple
+  //todo: global muting isn't this simple
   //(turns DAC on and off or something, causing small ~37-sample pulse when first muted)
   if(REG(FLG) & 0x40) {
     outl = 0;
diff --git a/higan/sfc/dsp/envelope.cpp b/higan/sfc/dsp/envelope.cpp
index 81a10533..67f615ab 100644
--- a/higan/sfc/dsp/envelope.cpp
+++ b/higan/sfc/dsp/envelope.cpp
@@ -1,5 +1,5 @@
 auto DSP::envelopeRun(Voice& v) -> void {
-  signed envelope = v.envelope;
+  int envelope = v.envelope;
 
   if(v.envelopeMode == EnvelopeRelease) {  //60%
     envelope -= 0x8;
@@ -8,8 +8,8 @@ auto DSP::envelopeRun(Voice& v) -> void {
     return;
   }
 
-  signed rate;
-  signed envelopeData = VREG(ADSR1);
+  int rate;
+  int envelopeData = VREG(ADSR1);
   if(state._adsr0 & 0x80) {  //99% ADSR
     if(v.envelopeMode >= EnvelopeDecay) {  //99%
       envelope--;
@@ -24,7 +24,7 @@ auto DSP::envelopeRun(Voice& v) -> void {
     }
   } else {  //GAIN
     envelopeData = VREG(GAIN);
-    signed mode = envelopeData >> 5;
+    int mode = envelopeData >> 5;
     if(mode < 4) {  //direct
       envelope = envelopeData << 4;
       rate = 31;
@@ -37,7 +37,7 @@ auto DSP::envelopeRun(Voice& v) -> void {
         envelope -= envelope >> 8;
       } else {  //6, 7: linear increase
         envelope += 0x20;
-        if(mode > 6 && (unsigned)v.hiddenEnvelope >= 0x600) {
+        if(mode > 6 && (uint)v.hiddenEnvelope >= 0x600) {
           envelope += 0x8 - 0x20;  //7: two-slope linear increase
         }
       }
@@ -48,8 +48,8 @@ auto DSP::envelopeRun(Voice& v) -> void {
   if((envelope >> 8) == (envelopeData >> 5) && v.envelopeMode == EnvelopeDecay) v.envelopeMode = EnvelopeSustain;
   v.hiddenEnvelope = envelope;
 
-  //unsigned cast because linear decrease underflowing also triggers this
-  if((unsigned)envelope > 0x7ff) {
+  //uint cast because linear decrease underflowing also triggers this
+  if((uint)envelope > 0x7ff) {
     envelope = (envelope < 0 ? 0 : 0x7ff);
     if(v.envelopeMode == EnvelopeAttack) v.envelopeMode = EnvelopeDecay;
   }
diff --git a/higan/sfc/dsp/gaussian.cpp b/higan/sfc/dsp/gaussian.cpp
index 55f0a6a3..8bc0873c 100644
--- a/higan/sfc/dsp/gaussian.cpp
+++ b/higan/sfc/dsp/gaussian.cpp
@@ -33,14 +33,14 @@ const int16 DSP::GaussianTable[512] = {
   1299, 1300, 1300, 1301, 1302, 1302, 1303, 1303, 1303, 1304, 1304, 1304, 1304, 1304, 1305, 1305,
 };
 
-auto DSP::gaussianInterpolate(const Voice& v) -> signed {
+auto DSP::gaussianInterpolate(const Voice& v) -> int {
   //make pointers into gaussian table based on fractional position between samples
-  signed offset = (v.gaussianOffset >> 4) & 0xff;
+  int offset = (v.gaussianOffset >> 4) & 0xff;
   const int16* forward = GaussianTable + 255 - offset;
   const int16* reverse = GaussianTable       + offset;  //mirror left half of gaussian table
 
   offset = v.bufferOffset + (v.gaussianOffset >> 12);
-  signed output;
+  int output;
   output  = (forward[  0] * v.buffer[offset + 0]) >> 11;
   output += (forward[256] * v.buffer[offset + 1]) >> 11;
   output += (reverse[256] * v.buffer[offset + 2]) >> 11;
diff --git a/higan/sfc/dsp/misc.cpp b/higan/sfc/dsp/misc.cpp
index d96c00ec..31434815 100644
--- a/higan/sfc/dsp/misc.cpp
+++ b/higan/sfc/dsp/misc.cpp
@@ -25,7 +25,7 @@ auto DSP::misc30() -> void {
 
   //noise
   if(counterPoll(REG(FLG) & 0x1f)) {
-    signed feedback = (state.noise << 13) ^ (state.noise << 14);
+    int feedback = (state.noise << 13) ^ (state.noise << 14);
     state.noise = (feedback & 0x4000) ^ (state.noise >> 1);
   }
 }
diff --git a/higan/sfc/dsp/modulo-array.hpp b/higan/sfc/dsp/modulo-array.hpp
index c03de4dd..85e8b1b8 100644
--- a/higan/sfc/dsp/modulo-array.hpp
+++ b/higan/sfc/dsp/modulo-array.hpp
@@ -1,14 +1,14 @@
-template<typename T, unsigned size>
+template<typename T, uint size>
 struct ModuloArray {
-  inline auto operator[](signed index) const -> T {
+  inline auto operator[](int index) const -> T {
     return buffer[size + index];
   }
 
-  inline auto read(signed index) const -> T {
+  inline auto read(int index) const -> T {
     return buffer[size + index];
   }
 
-  inline auto write(unsigned index, const T value) -> void {
+  inline auto write(uint index, const T value) -> void {
     buffer[index] =
     buffer[index + size] =
     buffer[index + size + size] = value;
diff --git a/higan/sfc/dsp/voice.cpp b/higan/sfc/dsp/voice.cpp
index 3dbe2cd4..baa9abdd 100644
--- a/higan/sfc/dsp/voice.cpp
+++ b/higan/sfc/dsp/voice.cpp
@@ -1,6 +1,6 @@
 inline auto DSP::voiceOutput(Voice& v, bool channel) -> void {
   //apply left/right volume
-  signed amp = (state._output * (int8)VREG(VOLL + channel)) >> 7;
+  int amp = (state._output * (int8)VREG(VOLL + channel)) >> 7;
 
   //add to output total
   state._mainOut[channel] += amp;
@@ -77,7 +77,7 @@ auto DSP::voice3c(Voice& v) -> void {
   }
 
   //gaussian interpolation
-  signed output = gaussianInterpolate(v);
+  int output = gaussianInterpolate(v);
 
   //noise
   if(state._non & v.vbit) {
diff --git a/higan/sfc/expansion/21fx/21fx.cpp b/higan/sfc/expansion/21fx/21fx.cpp
new file mode 100644
index 00000000..aed5f56e
--- /dev/null
+++ b/higan/sfc/expansion/21fx/21fx.cpp
@@ -0,0 +1,143 @@
+#include <sfc/sfc.hpp>
+
+namespace SuperFamicom {
+
+S21FX s21fx;
+
+auto S21FX::Enter() -> void {
+  while(true) scheduler.synchronize(), s21fx.main();
+}
+
+auto S21FX::main() -> void {
+  if(linkInit) linkInit(
+    {&S21FX::quit, this},
+    {&S21FX::usleep, this},
+    {&S21FX::readable, this},
+    {&S21FX::writable, this},
+    {&S21FX::read, this},
+    {&S21FX::write, this}
+  );
+  if(linkMain) linkMain({});
+  while(true) step(10'000'000);
+}
+
+auto S21FX::step(uint clocks) -> void {
+  clock += clocks * (uint64)cpu.frequency;
+  if(CPU::Threaded) {
+    if(clock >= 0 && !scheduler.synchronizing()) co_switch(cpu.thread);
+  } else {
+    while(clock >= 0) cpu.main();
+  }
+}
+
+auto S21FX::init() -> void {
+}
+
+auto S21FX::load() -> void {
+  resetVector.byte(0) = bus.read(0xfffc, 0x00);
+  resetVector.byte(1) = bus.read(0xfffd, 0x00);
+
+  for(auto& byte : ram) byte = 0xdb;  //stp
+  ram[0] = 0x6c;  //jmp ($fffc)
+  ram[1] = 0xfc;
+  ram[2] = 0xff;
+
+  bus.map({&S21FX::read, &s21fx}, {&S21FX::write, &s21fx}, 0x00, 0x00, 0xfffc, 0xfffd);
+  bus.map({&S21FX::read, &s21fx}, {&S21FX::write, &s21fx}, 0x00, 0x3f, 0x2184, 0x21ff);
+  bus.map({&S21FX::read, &s21fx}, {&S21FX::write, &s21fx}, 0x80, 0xbf, 0x2184, 0x21ff);
+
+  if(auto buffer = file::read({interface->path(ID::System), "21fx.rom"})) {
+    memory::copy(ram, sizeof(ram), buffer.data(), buffer.size());
+  }
+
+  string filename{interface->path(ID::SuperFamicom), "21fx.so"};
+  if(link.openAbsolute(filename)) {
+    linkInit = link.sym("fx_init");
+    linkMain = link.sym("fx_main");
+  }
+}
+
+auto S21FX::unload() -> void {
+  if(link.open()) link.close();
+  linkInit.reset();
+  linkMain.reset();
+}
+
+auto S21FX::power() -> void {
+}
+
+auto S21FX::reset() -> void {
+  create(S21FX::Enter, 10'000'000);
+  booted = false;
+}
+
+auto S21FX::read(uint24 addr, uint8 data) -> uint8 {
+  addr &= 0x40ffff;
+
+  if(addr == 0xfffc) return booted ? resetVector.byte(0) : (uint8)0x84;
+  if(addr == 0xfffd) return booted ? resetVector.byte(1) : (booted = true, (uint8)0x21);
+
+  if(addr >= 0x2184 && addr <= 0x21fd) return ram[addr - 0x2184];
+
+  if(addr == 0x21fe) return (
+    (linkBuffer.size() >     0) << 7  //1 = readable
+  | (snesBuffer.size() < 65536) << 6  //1 = writable
+  | (link.open())               << 5  //1 = connected
+  );
+
+  if(addr == 0x21ff) {
+    if(linkBuffer.size() > 0) {
+      data = linkBuffer.takeFirst();
+    }
+  }
+
+  return data;
+}
+
+auto S21FX::write(uint24 addr, uint8 data) -> void {
+  addr &= 0x40ffff;
+
+  if(addr == 0x21ff) {
+    if(snesBuffer.size() < 65536) {
+      snesBuffer.append(data);
+    }
+  }
+}
+
+auto S21FX::quit() -> bool {
+  step(1);
+  return false;
+}
+
+auto S21FX::usleep(uint microseconds) -> void {
+  step(10 * microseconds);
+}
+
+auto S21FX::readable() -> bool {
+  step(1);
+  return snesBuffer.size() > 0;
+}
+
+auto S21FX::writable() -> bool {
+  step(1);
+  return linkBuffer.size() < 65536;
+}
+
+//SNES -> Link
+auto S21FX::read() -> uint8 {
+  step(1);
+  if(snesBuffer.size() > 0) {
+    return snesBuffer.takeFirst();
+  }
+  return 0x00;
+}
+
+//Link -> SNES
+auto S21FX::write(uint8 data) -> void {
+  step(1);
+  if(linkBuffer.size() < 65536) {
+    linkBuffer.append(data);
+  }
+}
+
+}
diff --git a/higan/sfc/expansion/21fx/21fx.hpp b/higan/sfc/expansion/21fx/21fx.hpp
new file mode 100644
index 00000000..a71308e9
--- /dev/null
+++ b/higan/sfc/expansion/21fx/21fx.hpp
@@ -0,0 +1,41 @@
+struct S21FX : Thread, Memory {
+  static auto Enter() -> void;
+  auto main() -> void;
+  auto step(uint clocks) -> void;
+  auto init() -> void;
+  auto load() -> void;
+  auto unload() -> void;
+  auto power() -> void;
+  auto reset() -> void;
+
+  auto read(uint24 addr, uint8 data) -> uint8;
+  auto write(uint24 addr, uint8 data) -> void;
+
+private:
+  auto quit() -> bool;
+  auto usleep(uint) -> void;
+  auto readable() -> bool;
+  auto writable() -> bool;
+  auto read() -> uint8;
+  auto write(uint8) -> void;
+
+  bool booted = false;
+  uint16 resetVector;
+  uint8 ram[122];
+
+  nall::library link;
+  function<void (
+    function<bool ()>,      //quit
+    function<void (uint)>,  //usleep
+    function<bool ()>,      //readable
+    function<bool ()>,      //writable
+    function<uint8 ()>,     //read
+    function<void (uint8)>  //write
+  )> linkInit;
+  function<void (lstring)> linkMain;
+
+  vector<uint8> snesBuffer;  //SNES -> Link
+  vector<uint8> linkBuffer;  //Link -> SNES
+};
+
+extern S21FX s21fx;
diff --git a/higan/sfc/expansion/eboot/eboot.cpp b/higan/sfc/expansion/eboot/eboot.cpp
deleted file mode 100644
index 237d147b..00000000
--- a/higan/sfc/expansion/eboot/eboot.cpp
+++ /dev/null
@@ -1,49 +0,0 @@
-#include <sfc/sfc.hpp>
-
-namespace SuperFamicom {
-
-eBoot eboot;
-
-auto eBoot::init() -> void {
-}
-
-auto eBoot::load() -> void {
-  resetVector.byte(0) = bus.read(0xfffc, 0x00);
-  resetVector.byte(1) = bus.read(0xfffd, 0x00);
-
-  for(auto& byte : ram) byte = 0xdb;  //stp
-  ram[0] = 0x6c;  //jmp ($fffc)
-  ram[1] = 0xfc;
-  ram[2] = 0xff;
-
-  bus.map({&eBoot::read, &eboot}, {&eBoot::write, &eboot}, 0x00, 0x00, 0xfffc, 0xfffd);
-  bus.map({&eBoot::read, &eboot}, {&eBoot::write, &eboot}, 0x00, 0x3f, 0x2184, 0x21ff);
-  bus.map({&eBoot::read, &eboot}, {&eBoot::write, &eboot}, 0x80, 0xbf, 0x2184, 0x21ff);
-
-  if(auto buffer = file::read({interface->path(ID::System), "eboot.rom"})) {
-    memory::copy(ram, sizeof(ram), buffer.data(), buffer.size());
-  }
-}
-
-auto eBoot::unload() -> void {
-}
-
-auto eBoot::power() -> void {
-}
-
-auto eBoot::reset() -> void {
-  booted = false;
-}
-
-auto eBoot::read(uint24 addr, uint8 data) -> uint8 {
-  addr &= 0x40ffff;
-  if(addr == 0xfffc) return booted ? resetVector.byte(0) : (uint8)0x84;
-  if(addr == 0xfffd) return booted ? resetVector.byte(1) : (booted = true, (uint8)0x21);
-  if(addr >= 0x2184 && addr <= 0x21ff) return ram[addr - 0x2184];
-  return data;
-}
-
-auto eBoot::write(uint24 addr, uint8 data) -> void {
-}
-
-}
diff --git a/higan/sfc/expansion/eboot/eboot.hpp b/higan/sfc/expansion/eboot/eboot.hpp
deleted file mode 100644
index c7254131..00000000
--- a/higan/sfc/expansion/eboot/eboot.hpp
+++ /dev/null
@@ -1,17 +0,0 @@
-struct eBoot : Memory {
-  auto init() -> void;
-  auto load() -> void;
-  auto unload() -> void;
-  auto power() -> void;
-  auto reset() -> void;
-
-  auto read(uint24 addr, uint8 data) -> uint8;
-  auto write(uint24 addr, uint8 data) -> void;
-
-private:
-  bool booted = false;
-  uint16 resetVector;
-  uint8 ram[124];
-};
-
-extern eBoot eboot;
diff --git a/higan/sfc/expansion/expansion.hpp b/higan/sfc/expansion/expansion.hpp
index f5bd1714..9f42ca4e 100644
--- a/higan/sfc/expansion/expansion.hpp
+++ b/higan/sfc/expansion/expansion.hpp
@@ -1,3 +1,3 @@
 #include <sfc/expansion/satellaview/satellaview.hpp>
 #include <sfc/expansion/superdisc/superdisc.hpp>
-#include <sfc/expansion/eboot/eboot.hpp>
+#include <sfc/expansion/21fx/21fx.hpp>
diff --git a/higan/sfc/interface/interface.cpp b/higan/sfc/interface/interface.cpp
index bf1190f3..60d6039f 100644
--- a/higan/sfc/interface/interface.cpp
+++ b/higan/sfc/interface/interface.cpp
@@ -121,7 +121,7 @@ Interface::Interface() {
     this->device.append(device);
   }
 
-  { Device device{10, ID::ExpansionPort, "eBoot"};
+  { Device device{10, ID::ExpansionPort, "21fx"};
     this->device.append(device);
   }
 
diff --git a/higan/sfc/system/device.hpp b/higan/sfc/system/device.hpp
index ef69c8ab..b8289e3d 100644
--- a/higan/sfc/system/device.hpp
+++ b/higan/sfc/system/device.hpp
@@ -20,7 +20,7 @@ struct Device {
     //expansion port devices
     Satellaview,
     SuperDisc,
-    eBoot,
+    S21FX,
   };
 
   Device();
diff --git a/higan/sfc/system/system.cpp b/higan/sfc/system/system.cpp
index 452e1c82..ccfc6cff 100644
--- a/higan/sfc/system/system.cpp
+++ b/higan/sfc/system/system.cpp
@@ -33,7 +33,7 @@ auto System::init() -> void {
 
   satellaview.init();
   superdisc.init();
-  eboot.init();
+  s21fx.init();
 
   icd2.init();
   mcc.init();
@@ -83,7 +83,7 @@ auto System::load() -> void {
 
   if(expansionPort() == Device::ID::Satellaview) satellaview.load();
   if(expansionPort() == Device::ID::SuperDisc) superdisc.load();
-  if(expansionPort() == Device::ID::eBoot) eboot.load();
+  if(expansionPort() == Device::ID::S21FX) s21fx.load();
 
   if(cartridge.hasICD2()) icd2.load();
   if(cartridge.hasMCC()) mcc.load();
@@ -112,7 +112,7 @@ auto System::unload() -> void {
   if(!loaded()) return;
   if(expansionPort() == Device::ID::Satellaview) satellaview.unload();
   if(expansionPort() == Device::ID::SuperDisc) superdisc.unload();
-  if(expansionPort() == Device::ID::eBoot) eboot.unload();
+  if(expansionPort() == Device::ID::S21FX) s21fx.unload();
 
   if(cartridge.hasICD2()) icd2.unload();
   if(cartridge.hasMCC()) mcc.unload();
@@ -147,7 +147,7 @@ auto System::power() -> void {
 
   if(expansionPort() == Device::ID::Satellaview) satellaview.power();
   if(expansionPort() == Device::ID::SuperDisc) superdisc.power();
-  if(expansionPort() == Device::ID::eBoot) eboot.power();
+  if(expansionPort() == Device::ID::S21FX) s21fx.power();
 
   if(cartridge.hasICD2()) icd2.power();
   if(cartridge.hasMCC()) mcc.power();
@@ -178,7 +178,7 @@ auto System::reset() -> void {
 
   if(expansionPort() == Device::ID::Satellaview) satellaview.reset();
   if(expansionPort() == Device::ID::SuperDisc) superdisc.reset();
-  if(expansionPort() == Device::ID::eBoot) eboot.reset();
+  if(expansionPort() == Device::ID::S21FX) s21fx.reset();
 
   if(cartridge.hasICD2()) icd2.reset();
   if(cartridge.hasMCC()) mcc.reset();
@@ -210,6 +210,7 @@ auto System::reset() -> void {
   if(cartridge.hasSPC7110()) cpu.coprocessors.append(&spc7110);
   if(cartridge.hasMSU1()) cpu.coprocessors.append(&msu1);
   if(expansionPort() == Device::ID::SuperDisc) cpu.coprocessors.append(&superdisc);
+  if(expansionPort() == Device::ID::S21FX) cpu.coprocessors.append(&s21fx);
 
   scheduler.reset();
   device.connect(0, (Device::ID)settings.controllerPort1);
diff --git a/higan/ws/cpu/interrupt.cpp b/higan/ws/cpu/interrupt.cpp
index f888452d..5b0c91b7 100644
--- a/higan/ws/cpu/interrupt.cpp
+++ b/higan/ws/cpu/interrupt.cpp
@@ -11,6 +11,7 @@ auto CPU::poll() -> void {
 }
 
 auto CPU::raise(Interrupt irq) -> void {
+  if(!r.interruptEnable.bit((uint)irq)) return;
   r.interruptStatus.bit((uint)irq) = 1;
 }
 
diff --git a/higan/ws/cpu/io.cpp b/higan/ws/cpu/io.cpp
index d9500b98..ee9a199a 100644
--- a/higan/ws/cpu/io.cpp
+++ b/higan/ws/cpu/io.cpp
@@ -50,18 +50,17 @@ auto CPU::portRead(uint16 addr) -> uint8 {
   if(addr == 0x00a0) {
     bool model = system.model() != Model::WonderSwan;
     return (
-      1 << 7      //1 = built-in self-test passed
-    | 1 << 2      //0 = 8-bit bus width; 1 = 16-bit bus width
+      1     << 0  //0 = BIOS mapped; 1 = cartridge mapped
     | model << 1  //0 = WonderSwan; 1 = WonderSwan Color or SwanCrystal
-    | 1 << 0      //0 = BIOS mapped; 1 = cartridge mapped
+    | 1     << 2  //0 = 8-bit bus width; 1 = 16-bit bus width
+    | 1     << 7  //1 = built-in self-test passed
     );
   }
 
   //INT_BASE
-  if(addr == 0x00b0) {
-    if(system.model() == Model::WonderSwan) return r.interruptBase | 3;
-    return r.interruptBase;
-  }
+  if(addr == 0x00b0) return (
+    r.interruptBase | (system.model() == Model::WonderSwan ? 3 : 0)
+  );
 
   //SER_DATA
   if(addr == 0x00b1) return r.serialData;
@@ -92,42 +91,38 @@ auto CPU::portRead(uint16 addr) -> uint8 {
 
 auto CPU::portWrite(uint16 addr, uint8 data) -> void {
   //DMA_SRC
-  if(addr == 0x0040) { r.dmaSource.byte(0) = data & ~1; return; }
-  if(addr == 0x0041) { r.dmaSource.byte(1) = data; return; }
-  if(addr == 0x0042) { r.dmaSource.byte(2) = data; return; }
+  if(addr == 0x0040) r.dmaSource.byte(0) = data & ~1;
+  if(addr == 0x0041) r.dmaSource.byte(1) = data;
+  if(addr == 0x0042) r.dmaSource.byte(2) = data;
 
   //DMA_DST
-  if(addr == 0x0044) { r.dmaTarget.byte(0) = data & ~1; return; }
-  if(addr == 0x0045) { r.dmaTarget.byte(1) = data; return; }
+  if(addr == 0x0044) r.dmaTarget.byte(0) = data & ~1;
+  if(addr == 0x0045) r.dmaTarget.byte(1) = data;
 
   //DMA_LEN
-  if(addr == 0x0046) { r.dmaLength.byte(0) = data & ~1; return; }
-  if(addr == 0x0047) { r.dmaLength.byte(1) = data; return; }
+  if(addr == 0x0046) r.dmaLength.byte(0) = data & ~1;
+  if(addr == 0x0047) r.dmaLength.byte(1) = data;
 
   //DMA_CTRL
   if(addr == 0x0048) {
-    r.dmaEnable = data.bit(7);
     r.dmaMode   = data.bit(0);
+    r.dmaEnable = data.bit(7);
     if(r.dmaEnable) dmaTransfer();
-    return;
   }
 
   //WSC_SYSTEM
   if(addr == 0x0062) {
     //todo: d0 = 1 powers off system
-    return;
   }
 
   //HW_FLAGS
   if(addr == 0x00a0) {
     //todo: d2 (bus width) bit is writable; but ... it will do very bad things
-    return;
   }
 
   //INT_BASE
   if(addr == 0x00b0) {
     r.interruptBase = (system.model() == Model::WonderSwan) ? data & ~7 : data & ~1;
-    return;
   }
 
   //SER_DATA
@@ -136,7 +131,7 @@ auto CPU::portWrite(uint16 addr, uint8 data) -> void {
   //INT_ENABLE
   if(addr == 0x00b2) {
     r.interruptEnable = data;
-    return;
+    r.interruptStatus &= ~r.interruptEnable;
   }
 
   //SER_STATUS
@@ -156,6 +151,5 @@ auto CPU::portWrite(uint16 addr, uint8 data) -> void {
   if(addr == 0x00b6) {
     //acknowledge only edge-sensitive interrupts
     r.interruptStatus &= ~(data & 0b11110010);
-    return;
   }
 }
diff --git a/higan/ws/ppu/latch.cpp b/higan/ws/ppu/latch.cpp
index f75ee7c0..f47f48a0 100644
--- a/higan/ws/ppu/latch.cpp
+++ b/higan/ws/ppu/latch.cpp
@@ -28,25 +28,10 @@ auto PPU::latchRegisters() -> void {
 auto PPU::latchSprites() -> void {
   l.spriteCount = 0;
   if(!l.spriteEnable) return;
-
-  uint offset = 0;
-  bool windowInside = s.vclk >= l.spriteWindowY0 && s.vclk <= l.spriteWindowY1;
   for(auto index : range(l.oamCount)) {
     uint32 attributes = l.oam[!s.field][index];
-
-    auto& sprite = l.sprite[l.spriteCount];
-    sprite.x = attributes.bits(24,31);
-    if(sprite.x > 224 && sprite.x < 249) continue;
-    sprite.y = attributes.bits(16,23);
-    if((uint8)(s.vclk - sprite.y) > 7) continue;
-    sprite.vflip = attributes.bit(15);
-    sprite.hflip = attributes.bit(14);
-    sprite.priority = attributes.bit(13);
-    sprite.window = attributes.bit(12);
-    if(l.spriteWindowEnable && !sprite.window && !windowInside) continue;
-    sprite.palette = 8 + attributes.bits(9,11);
-    sprite.tile = attributes.bits(0,8);
-
+    if((uint8)(s.vclk - attributes.bits(16,23)) > 7) continue;
+    l.sprite[l.spriteCount] = attributes;
     if(++l.spriteCount >= 32) break;
   }
 }
diff --git a/higan/ws/ppu/ppu.hpp b/higan/ws/ppu/ppu.hpp
index f8c2bd47..1c7f311b 100644
--- a/higan/ws/ppu/ppu.hpp
+++ b/higan/ws/ppu/ppu.hpp
@@ -36,17 +36,6 @@ struct PPU : Thread, IO {
     uint12 color;
   };
 
-  struct Sprite {
-    uint8 x;
-    uint8 y;
-    uint1 vflip;
-    uint1 hflip;
-    uint1 priority;
-    uint1 window;
-    uint4 palette;  //latchSprites() always sets bit3
-    uint9 tile;
-  };
-
   uint12 output[224 * 144];
 
   struct State {
@@ -84,7 +73,7 @@ struct PPU : Thread, IO {
     uint8 spriteWindowY1;
 
     //latchSprites()
-    Sprite sprite[32];
+    uint32 sprite[32];
     uint spriteCount;
 
     //latchOAM()
diff --git a/higan/ws/ppu/render.cpp b/higan/ws/ppu/render.cpp
index 977ec3e9..782bcc51 100644
--- a/higan/ws/ppu/render.cpp
+++ b/higan/ws/ppu/render.cpp
@@ -96,19 +96,20 @@ auto PPU::renderScreenTwo() -> void {
 }
 
 auto PPU::renderSprite() -> void {
-  bool windowInside = s.hclk >= l.spriteWindowX0 && s.hclk <= l.spriteWindowY0;
+  bool windowInside = s.vclk >= l.spriteWindowY0 && s.vclk <= l.spriteWindowY1
+                   && s.hclk >= l.spriteWindowX0 && s.hclk <= l.spriteWindowX1;
   for(auto index : range(l.spriteCount)) {
-    auto& sprite = l.sprite[index];
-    if(l.spriteWindowEnable && !sprite.window && !windowInside) continue;
-    if((uint8)(s.hclk - sprite.x) > 7) continue;
+    auto sprite = l.sprite[index];
+    if(l.spriteWindowEnable && sprite.bit(12) == windowInside) continue;
+    if((uint8)(s.hclk - sprite.bits(24,31)) > 7) continue;
 
-    uint3 tileY = (s.vclk - sprite.y) ^ sprite.vflip * 7;
-    uint3 tileX = (s.hclk - sprite.x) ^ sprite.hflip * 7;
-    uint4 tileColor = renderFetch(sprite.tile, tileY, tileX);
-    if(renderTransparent(sprite.palette.bit(2), tileColor)) continue;
-    if(!sprite.priority && s.pixel.source == Pixel::Source::ScreenTwo) continue;
+    uint3 tileY = (s.vclk - sprite.bits(16,23)) ^ sprite.bit(15) * 7;
+    uint3 tileX = (s.hclk - sprite.bits(24,31)) ^ sprite.bit(14) * 7;
+    uint4 tileColor = renderFetch(sprite.bits(0,8), tileY, tileX);
+    if(renderTransparent(sprite.bit(11), tileColor)) continue;
+    if(!sprite.bit(13) && s.pixel.source == Pixel::Source::ScreenTwo) continue;
 
-    s.pixel = {Pixel::Source::Sprite, renderPalette(sprite.palette, tileColor)};
+    s.pixel = {Pixel::Source::Sprite, renderPalette(8 + sprite.bits(9,11), tileColor)};
     break;
   }
 }
diff --git a/higan/ws/ppu/serialization.cpp b/higan/ws/ppu/serialization.cpp
index 33ea78c0..e0f682c3 100644
--- a/higan/ws/ppu/serialization.cpp
+++ b/higan/ws/ppu/serialization.cpp
@@ -29,21 +29,10 @@ auto PPU::serialize(serializer& s) -> void {
   s.integer(l.spriteWindowX1);
   s.integer(l.spriteWindowY1);
 
-  for(uint n : range(32)) {
-    s.integer(l.sprite[n].x);
-    s.integer(l.sprite[n].y);
-    s.integer(l.sprite[n].vflip);
-    s.integer(l.sprite[n].hflip);
-    s.integer(l.sprite[n].priority);
-    s.integer(l.sprite[n].window);
-    s.integer(l.sprite[n].palette);
-    s.integer(l.sprite[n].tile);
-  }
+  s.array(l.sprite);
   s.integer(l.spriteCount);
 
-  for(uint n : range(2)) {
-    s.array(l.oam[n]);
-  }
+  for(uint n : range(2)) s.array(l.oam[n]);
   s.integer(l.oamCount);
 
   s.integer(r.screenOneEnable);
@@ -83,9 +72,7 @@ auto PPU::serialize(serializer& s) -> void {
   s.integer(r.vtotal);
   s.integer(r.vblank);
   s.array(r.pool);
-  for(uint n : range(16)) {
-    s.array(r.palette[n].color);
-  }
+  for(uint n : range(16)) s.array(r.palette[n].color);
   s.integer(r.htimerEnable);
   s.integer(r.htimerRepeat);
   s.integer(r.vtimerEnable);