diff --git a/src/audio.ts b/src/audio.ts
index 6d961e03..ceddf12d 100644
--- a/src/audio.ts
+++ b/src/audio.ts
@@ -480,15 +480,13 @@ export var SampleAudio = function(clockfreq) {
   }
 
   this.feedSample = function(value, count) {
-    while (count-- > 0) {
-      accum += value;
-      sfrac += sinc;
-      while (sfrac >= 1) {
-        sfrac -= 1;
-        value *= sfrac;
-        this.addSingleSample(accum - value);
-        accum = value;
-      }
+    accum += value * count;
+    sfrac += sinc * count;
+    while (sfrac >= 1) {
+      sfrac -= 1;
+      value *= sfrac;
+      this.addSingleSample(accum - value);
+      accum = value;
     }
   }
   
diff --git a/src/cpu/ZilogZ80.ts b/src/cpu/ZilogZ80.ts
index f6e37d06..df324678 100644
--- a/src/cpu/ZilogZ80.ts
+++ b/src/cpu/ZilogZ80.ts
@@ -3408,6 +3408,9 @@ export class Z80 implements CPU, InstructionBased, IOBusConnected, SavesState<Z8
   getPC() {
     return this.cpu.getPC();
   }
+  isHalted() {
+   return this.cpu.getHalted();
+  }
   saveState() {
     return this.cpu.saveState();
   }
diff --git a/src/devices.ts b/src/devices.ts
index 64fdb3f7..48c64fb0 100644
--- a/src/devices.ts
+++ b/src/devices.ts
@@ -305,11 +305,6 @@ export abstract class BasicMachine implements HasCPU, Bus, SampledAudioSource, A
       inputs:this.inputs.slice(0)
     };
   }
-  advanceCPUMultiple(cycles : number) : number {
-    for (var i=0; i<cycles; i+=this.advanceCPU())
-      ;
-    return i;
-  }
   advanceCPU() {
     var c = this.cpu as any;
     var n = 1;
diff --git a/src/platform/sound_williams.ts b/src/platform/sound_williams.ts
index 28c04a21..a5850da7 100644
--- a/src/platform/sound_williams.ts
+++ b/src/platform/sound_williams.ts
@@ -1,8 +1,9 @@
 "use strict";
 
-import { Platform, BaseZ80Platform } from "../baseplatform";
+import { Z80, Z80State } from "../cpu/ZilogZ80";
+import { BasicMachine, CPU, Bus } from "../devices";
+import { Platform, BaseZ80MachinePlatform } from "../baseplatform";
 import { PLATFORMS, RAM, newAddressDecoder, padBytes, noise, setKeyboardFromMap, AnimationTimer, RasterVideo, Keys, makeKeycodeMap } from "../emu";
-import { hex } from "../util";
 import { SampleAudio } from "../audio";
 
 var WILLIAMS_SOUND_PRESETS = [
@@ -33,126 +34,89 @@ var WILLIAMS_SOUND_PRESETS = [
 
 ****************************************************************************/
 
-var WilliamsSoundPlatform = function(mainElement) {
-  var self = this;
-  this.__proto__ = new (BaseZ80Platform as any)();
+class WilliamsSound extends BasicMachine {
+  cpuFrequency = 18432000 / 6; // 3.072 MHz
+  cpuCyclesPerFrame = this.cpuFrequency / 60;
+  cpuAudioFactor = 32;
+  canvasWidth = 256;
+  numVisibleScanlines = 256;
+  defaultROMSize = 0x4000;
+  sampleRate = this.cpuFrequency;
+  overscan = true;
+  
+  cpu : Z80;
+  ram = new Uint8Array(0x400);
+  iobus : Bus;
+  
+  command : number = 0;
+  dac : number = 0;
+  dac_float : number = 0;
+  xpos : number = 0;
 
-  var cpu, ram, rom, membus, iobus;
-  var audio, master;
-  var video, timer;
-  var command = 0;
-  var dac = 0;
-  var dac_float = 0.0
-  var current_buffer;
-  var last_tstate = 0;
-  var tstates = 0;
-  var pixels;
+  read = newAddressDecoder([
+    [0x0000, 0x3fff, 0x3fff, (a) => { return this.rom && this.rom[a]; }],
+    [0x4000, 0x7fff, 0x3ff, (a) => { return this.ram[a]; }]
+  ]);
 
-  var cpuFrequency = 18432000 / 6; // 3.072 MHz
-  var cpuCyclesPerFrame = cpuFrequency / 60;
-  var cpuAudioFactor = 32;
-
-  function fillBuffer() {
-    var t = tstates / cpuAudioFactor;
-    while (last_tstate < t) {
-      current_buffer[last_tstate++] = dac_float;
-    }
-  }
-
-  this.getPresets = function() {
-    return WILLIAMS_SOUND_PRESETS;
-  }
-
-  this.start = function() {
-    ram = new RAM(0x400);
-    membus = {
-      read: newAddressDecoder([
-        [0x0000, 0x3fff, 0x3fff, function(a) { return rom ? rom[a] : null; }],
-        [0x4000, 0x7fff, 0x3ff, function(a) { return ram.mem[a]; }]
-      ]),
-      write: newAddressDecoder([
-        [0x4000, 0x7fff, 0x3ff, function(a, v) { ram.mem[a] = v; }],
-      ]),
-    };
-    iobus = {
-      read: function(addr) {
-        return command & 0xff;
+  write = newAddressDecoder([
+    [0x4000, 0x7fff, 0x3ff, (a, v) => { this.ram[a] = v; }],
+  ]);
+  
+  constructor() {
+    super();
+    this.cpu = new Z80();
+    this.connectCPUMemoryBus(this);
+    this.connectCPUIOBus({
+      read: (addr) => {
+        return this.command & 0xff;
       },
-      write: function(addr, val) {
-        dac = val & 0xff;
-        dac_float = ((dac & 0x80) ? -256 + dac : dac) / 128.0;
-        fillBuffer();
-      }
-    };
-    this.readAddress = membus.read;
-    cpu = this.newCPU(membus, iobus);
-    audio = new SampleAudio(cpuFrequency / cpuAudioFactor);
-    audio.callback = function(lbuf) {
-      if (self.isRunning()) {
-        current_buffer = lbuf;
-        last_tstate = 0;
-        tstates = 0;
-        while (tstates < lbuf.length * cpuAudioFactor) {
-          tstates += self.runCPU(cpu, 1);
-        }
-        fillBuffer();
-        for (var i = 0; i < 256; i++) {
-          var y = Math.round((current_buffer[i] * 127) + 128);
-          pixels[i + y * 256] = 0xff33ff33;
-        }
-      }
-    };
-    video = new RasterVideo(mainElement, 256, 256);
-    video.create();
-    video.setKeyboardEvents(function(key, code, flags) {
-      var intr = (key - 49);
-      if (intr >= 0 && (flags & 1)) {
-        command = intr & 0xff;
-        cpu.reset();
-      }
-    });
-    pixels = video.getFrameData();
-    timer = new AnimationTimer(30, function() {
-      if (self.isRunning()) {
-        video.updateFrame();
-        pixels.fill(0);
+      write: (addr, val) => {
+        let dac = this.dac = val & 0xff;
+        this.dac_float = ((dac & 0x80) ? -256 + dac : dac) / 128.0;
       }
     });
   }
-
-  this.loadROM = function(title, data) {
-    rom = padBytes(data, 0x4000);
-    cpu.reset();
+  
+  advanceFrame(maxCycles, trap) : number {
+    this.pixels && this.pixels.fill(0); // clear waveform
+    maxCycles = Math.min(this.cpuCyclesPerFrame, maxCycles);
+    var n = 0;
+    while (n < maxCycles) {
+      if (trap && trap()) {
+        break;
+      }
+      n += this.advanceCPU();
+    }
+    return n;
+  }
+  
+  advanceCPU() {
+    var n = super.advanceCPU();
+    this.audio && this.audio.feedSample(this.dac_float, n);
+    // draw waveform on screen
+    if (this.pixels && !this.cpu.isHalted()) {
+      this.pixels[((this.xpos >> 8) & 0xff) + ((255-this.dac) << 8)] = 0xff33ff33;
+      this.xpos = (this.xpos + n) & 0xffffff;
+    }
+    return n;
   }
 
-  this.loadState = function(state) {
-    cpu.loadState(state.c);
-    ram.mem.set(state.b);
-  }
-  this.saveState = function() {
-    return {
-      c: self.getCPUState(),
-      b: ram.mem.slice(0),
-    };
-  }
-  this.getCPUState = function() {
-    return cpu.saveState();
-  }
-
-  this.isRunning = function() {
-    return timer && timer.isRunning();
-  }
-  this.pause = function() {
-    timer.stop();
-    audio.stop();
-  }
-  this.resume = function() {
-    timer.start();
-    audio.start();
-  }
-  this.reset = function() {
-    cpu.reset();
+  setKeyInput(key:number, code:number, flags:number) : void {
+    var intr = (key - 49);
+    if (intr >= 0 && (flags & 1)) {
+      this.command = intr & 0xff;
+      this.cpu.reset();
+    }
   }
 }
 
+export class WilliamsSoundPlatform extends BaseZ80MachinePlatform<WilliamsSound> {
+
+  newMachine()          { return new WilliamsSound(); }
+  getPresets()          { return WILLIAMS_SOUND_PRESETS; }
+  getDefaultExtension() { return ".c"; };
+  readAddress(a)        { return this.machine.read(a); }
+
+}
+
 PLATFORMS['sound_williams-z80'] = WilliamsSoundPlatform;
diff --git a/test/cli/testplatforms.js b/test/cli/testplatforms.js
index a3b4900a..89ab64fd 100644
--- a/test/cli/testplatforms.js
+++ b/test/cli/testplatforms.js
@@ -262,7 +262,6 @@ describe('Platform Replay', () => {
       }
     });
   });
-/*
   it('Should run sound_williams', () => {
     var platform = testPlatform('sound_williams-z80', 'swave.c.rom', 72, (platform, frameno) => {
       if (frameno == 60) {
@@ -270,7 +269,6 @@ describe('Platform Replay', () => {
       }
     });
   });
-*/
 
   it('Should run astrocade', () => {
     var platform = testPlatform('astrocade', 'cosmic.c.rom', 92, (platform, frameno) => {