diff --git a/index.html b/index.html
index dd403a1d..bd8fe70a 100644
--- a/index.html
+++ b/index.html
@@ -320,6 +320,7 @@ function require(modname) {
 <script src="tss/js/tss/AudioLooper.js"></script>
 <script src="tss/js/Log.js"></script>
 
+<script src="gen/video/tms9918a.js"></script>
 <script src="gen/util.js"></script>
 <script src="gen/store.js"></script>
 <script src="src/vlist.js"></script>
diff --git a/presets/nes/ex1.asm b/presets/nes/ex1.asm
index 2da8c6bc..90fc13d9 100644
--- a/presets/nes/ex1.asm
+++ b/presets/nes/ex1.asm
@@ -1,4 +1,4 @@
-
+
 	include "nesdefs.asm"
 
 ;;;;; VARIABLES
@@ -26,9 +26,9 @@ Start:
         sta PPU_ADDR	; PPU addr = $0000
         sta PPU_SCROLL
         sta PPU_SCROLL  ; scroll = $0000
-        lda #$90
+        lda #CTRL_NMI
         sta PPU_CTRL	; enable NMI
-        lda #$1e
+        lda #MASK_SPR|MASK_BG|MASK_SPR_CLIP|MASK_BG_CLIP
         sta PPU_MASK 	; enable rendering
 .endless
 	jmp .endless	; endless loop
@@ -38,15 +38,15 @@ FillVRAM: subroutine
 	txa
 	ldy #$20
 	sty PPU_ADDR
-	sta PPU_ADDR
-	ldy #$10
+	sta PPU_ADDR	; PPU addr = $2000
+	ldy #$10	; $10 (16) 256-byte pages
 .loop:
-	sta PPU_DATA
-        adc #7
+	sta PPU_DATA	; write to VRAM
+        adc #7		; add 7 to make randomish pattern
 	inx
 	bne .loop
-	dey
-	bne .loop
+	dey		; next page
+	bne .loop	; out of pages?
         rts
 
 ; set palette colors
@@ -54,14 +54,14 @@ SetPalette: subroutine
         ldy #$00
 	lda #$3f
 	sta PPU_ADDR
-	sty PPU_ADDR
-	ldx #32
+	sty PPU_ADDR	; PPU addr = 0x3f00
+	ldx #32		; 32 palette colors
 .loop:
-	lda Palette,y
-	sta PPU_DATA
+	lda Palette,y	; load from ROM
+	sta PPU_DATA	; store to palette
         iny
 	dex
-	bne .loop
+	bne .loop	; loop until 32 colors stored
         rts
 
 
@@ -77,14 +77,9 @@ NMIHandler:
 ; update scroll position (must be done after VRAM updates)
 	inc ScrollPos
         lda ScrollPos
-        sta PPU_SCROLL
+        sta PPU_SCROLL	; X scroll position
         lda #0
-        sta PPU_SCROLL
-; TODO: write high bits to PPUCTRL
-	lda ScrollPos
-        and #0
-	ora #$90	; enable NMI
-        sta PPU_CTRL
+        sta PPU_SCROLL	; Y scroll position
 ; reload registers
         pla	; reload A
 	rti
diff --git a/src/audio.ts b/src/audio.ts
index 6ca18bc7..999be8d0 100644
--- a/src/audio.ts
+++ b/src/audio.ts
@@ -19,7 +19,7 @@ export class AY38910_Audio {
   master : MasterAudio;
   psg = new PsgDeviceChannel();
   curreg = 0;
-  
+
   constructor(master : MasterAudio) {
     this.master = master;
     this.psg.setMode(PsgDeviceChannel.MODE_SIGNED);
@@ -41,6 +41,21 @@ export class AY38910_Audio {
   }
 }
 
+export class SN76489_Audio {
+  master : MasterAudio;
+  psg = new PsgDeviceChannel();
+
+  constructor(master : MasterAudio) {
+    this.master = master;
+    this.psg.setMode(PsgDeviceChannel.MODE_SIGNED);
+    this.psg.setDevice(PsgDeviceChannel.DEVICE_SN76489);
+    master.master.addChannel(this.psg);
+  }
+  setData(val : number) {
+    this.psg.writeRegisterSN(0, val & 0xff);
+  }
+}
+
 // https://en.wikipedia.org/wiki/POKEY
 // https://user.xmission.com/~trevin/atari/pokey_regs.html
 // http://krap.pl/mirrorz/atari/homepage.ntlworld.com/kryten_droid/Atari/800XL/atari_hw/pokey.htm
diff --git a/src/platform/coleco.ts b/src/platform/coleco.ts
index ba89b58b..e2387fa6 100644
--- a/src/platform/coleco.ts
+++ b/src/platform/coleco.ts
@@ -1,7 +1,10 @@
 "use strict";
 
-import { Platform, BaseMAMEPlatform, getToolForFilename_z80 } from "../baseplatform";
-import { PLATFORMS } from "../emu";
+import { Platform, BaseMAMEPlatform, BaseZ80Platform, getToolForFilename_z80 } from "../baseplatform";
+import { PLATFORMS, RAM, newAddressDecoder, padBytes, noise, setKeyboardFromMap, AnimationTimer, RasterVideo, Keys, makeKeycodeMap } from "../emu";
+import { hex, lzgmini, stringToByteArray } from "../util";
+import { MasterAudio, SN76489_Audio } from "../audio";
+import { TMS9918A } from "../video/tms9918a";
 
 // http://www.colecovision.eu/ColecoVision/development/tutorial1.shtml
 // http://www.colecovision.eu/ColecoVision/development/libcv.shtml
@@ -31,6 +34,228 @@ var ColecoVision_PRESETS = [
   {id:'platform.c', name:'Platform Game'},
 ];
 
+var COLECOVISION_KEYCODE_MAP = makeKeycodeMap([
+  [Keys.VK_UP,    0, 0x1],
+  [Keys.VK_DOWN,  0, 0x4],
+  [Keys.VK_LEFT,  0, 0x8],
+  [Keys.VK_RIGHT, 0, 0x2],
+  [Keys.VK_SPACE, 0, 0x40],
+  [Keys.VK_CONTROL, 1, 0x40],
+
+  [Keys.VK_W, 2, 0x1],
+  [Keys.VK_S, 2, 0x4],
+  [Keys.VK_A, 2, 0x8],
+  [Keys.VK_D, 2, 0x2],
+  [Keys.VK_Z, 2, 0x40],
+  [Keys.VK_X, 3, 0x40],
+]);
+
+/// standard emulator
+
+const _ColecoVisionPlatform = function(mainElement) {
+
+  const cpuFrequency = 3579545; // MHz
+  const canvasWidth = 304;
+  const numTotalScanlines = 262;
+  const numVisibleScanlines = 240;
+  const cpuCyclesPerLine = Math.round(cpuFrequency / 60 / numTotalScanlines);
+
+  var cpu, ram, membus, iobus, rom, bios;
+  var video, vdp, timer;
+  var audio, psg;
+  var inputs = new Uint8Array(4);
+  var keypadMode = false;
+
+  class ColecoVisionPlatform extends BaseZ80Platform implements Platform {
+
+    getPresets() { return ColecoVision_PRESETS; }
+    getToolForFilename = getToolForFilename_z80;
+    getDefaultExtension() { return ".c"; };
+
+    start() {
+       ram = new RAM(1024);
+       bios = new lzgmini().decode(stringToByteArray(atob(COLECO_BIOS_LZG)));
+       membus = {
+         read: newAddressDecoder([
+           [0x0000, 0x1fff, 0x1fff, function(a) { return bios ? bios[a] : 0; }],
+           [0x6000, 0x7fff,  0x3ff, function(a) { return ram.mem[a]; }],
+           [0x8000, 0xffff, 0x7fff, function(a) { return rom ? rom[a] : 0; }],
+	       ]),
+         write: newAddressDecoder([
+           [0x6000, 0x7fff,  0x3ff, function(a,v) { ram.mem[a] = v; }],
+         ]),
+         isContended: function() { return false; },
+      };
+      iobus = {
+        read: function(addr) {
+  				addr &= 0xff;
+          //console.log('IO read', hex(addr,4));
+          switch (addr) {
+            case 0xfc: return inputs[keypadMode?1:0] ^ 0xff;
+            case 0xff: return inputs[keypadMode?3:2] ^ 0xff;
+          }
+          if (addr >= 0xa0 && addr <= 0xbf) {
+            if (addr & 1)
+              return vdp.readStatus();
+            else
+              return vdp.readData();
+          }
+          return 0;
+      	},
+      	write: function(addr, val) {
+  				addr &= 0xff;
+  				val &= 0xff;
+          //console.log('IO write', hex(addr,4), hex(val,2));
+          switch (addr >> 4) {
+            case 0x8: case 0x9: keypadMode = true; break;
+            case 0xc: case 0xd: keypadMode = false; break;
+            case 0xa: case 0xb:
+              if (addr & 1)
+                return vdp.writeAddress(val);
+              else
+                return vdp.writeData(val);
+            case 0xf: psg.setData(val); break;
+          }
+      	}
+      };
+      cpu = this.newCPU(membus, iobus);
+      video = new RasterVideo(mainElement,canvasWidth,numVisibleScanlines);
+      video.create();
+      audio = new MasterAudio();
+      psg = new SN76489_Audio(audio);
+      var cru = {
+        setVDPInterrupt: (b) => {
+          if (b) {
+            cpu.nonMaskableInterrupt();
+          } else {
+            // TODO: reset interrupt?
+          }
+        }
+      };
+      vdp = new TMS9918A(video.canvas, cru, false);
+      setKeyboardFromMap(video, inputs, COLECOVISION_KEYCODE_MAP);
+      timer = new AnimationTimer(60, this.nextFrame.bind(this));
+    }
+
+    readAddress(addr) {
+      return membus.read(addr);
+    }
+
+    advance(novideo : boolean) {
+      for (var sl=0; sl<numTotalScanlines; sl++) {
+        this.runCPU(cpu, cpuCyclesPerLine);
+        if (sl < numVisibleScanlines)
+          vdp.drawScanline(sl);
+      }
+      vdp.updateCanvas();
+    }
+
+    loadROM(title, data) {
+      rom = padBytes(data, 0x8000);
+      this.reset();
+    }
+
+    loadState(state) {
+      cpu.loadState(state.c);
+      ram.mem.set(state.b);
+      vdp.restoreState(state.vdp);
+      keypadMode = state.kpm;
+      inputs.set(state.in);
+    }
+    saveState() {
+      return {
+        c:this.getCPUState(),
+        b:ram.mem.slice(0),
+        vdp:vdp.getState(),
+        kpm:keypadMode,
+        in:inputs.slice(0),
+      };
+    }
+    loadControlsState(state) {
+      inputs[0] = state.in0;
+      inputs[1] = state.in1;
+      inputs[2] = state.in2;
+    }
+    saveControlsState() {
+      return {
+        in0:inputs[0],
+        in1:inputs[1],
+        in2:inputs[2],
+      };
+    }
+    getCPUState() {
+      return cpu.saveState();
+    }
+
+    isRunning() {
+      return timer && timer.isRunning();
+    }
+    pause() {
+      timer.stop();
+      audio.stop();
+    }
+    resume() {
+      timer.start();
+      audio.start();
+    }
+    reset() {
+      cpu.reset();
+      cpu.setTstates(0);
+    }
+
+    getDebugCategories() {
+      return super.getDebugCategories().concat(['VDP']);
+    }
+    getDebugInfo(category, state) {
+      switch (category) {
+        case 'VDP': return this.vdpStateToLongString(state.vdp);
+        default: return super.getDebugInfo(category, state);
+      }
+    }
+    vdpStateToLongString(ppu) {
+      return vdp.getRegsString();
+    }
+  }
+  return new ColecoVisionPlatform();
+}
+
+var COLECO_BIOS_LZG = `
+TFpHAAAgAAAAB7djQcnHAQEDBgcx/3MYawAAAMMMgAehB+EPB+USB+UVB+UYB+UbB+UeB+QHHAZm
+IYA8igUCBYIAKgCAff5VIAl8/qogBCoKgOnHAwkfgICAAAMFT6CgB4LgByEH4WDAYMBABlggQIAg
+B+HAwOCgYAMGKweBQAYxBphAQEAG+KBABnAGEuAGUAabB+QA4AflBkggIAYyB+FgoKCgwAZdwAY5
+B+HABhAGYAfhIAZQoKDgIAMCcOCAwAaIYIDgoAZY4AMFOAYGBsgGIAZYAwJWBlAAQAMEcAYfQAZ4
+BhoDA3gGBgaQBjgGGwYfoOCAAwLIB+EDA/DAoAchAwNggAaQwAMFmOCAByEH5QZ4AwKABligAwUw
+4EBAQAZYICAgoAMCUAYuBpAGPwawoOAG4AfhAyNQQKCgBqDAoMADJECgoOADBGjgwAZYYIADBPgD
+AlADBEigAwVooAMFCAMEQAYHAwRQBg8GUAMiEAMEoAMEcAMD6gaQICAGyAADJZgDJ4gDI7gAwGAD
+I0CAwAME6AMC+QMCaCBgAwRwAGCgwAaIQOADA2AGJiAH4gZoAwPgA0M6ACAAAwX4gKDAAwPAAyLP
+AwNgAwXwAyNJAwR+AwX4oMADRQBgAyOgAyJxB+PAYANDEOBAQAMDeAMF+AfhA0RQAyJBB+NAAwPI
+BncGkOBgwAZQYECABrADQs8DAkjAQCBAA0QYAAMDUAcLOERsRFREOAA4fFR8RHw4AAAofHx8OBAA
+ABA4B+MQODgQfHwDBQgQBhgAADAwB4H8/PzMzAeBAAB4SEh4BkiEtLSEBggcDDRISDAAOEREOBAG
+eBgUEDBwYAAMNCw0LGxgAABUOGw4VAAAIDA4PDgwIAAIGDh4OBgIAwJXEAMCaCgHAgAoADxUVDQU
+FBQAOEQwKBhEAwNwAAB4eAMGIAchfBAHAQAHggMEqBh8GAfBABAwfDAH4gAAQEBAfAAAKCh8KCgG
+DxA4OHwGB3x8ODgGLwcHBg8GfgBsbEgGyQZnfCgAIDhAMAhwEABkZAgQIExMACBQUCBUSDQAMDAD
+ZEsQIAcCEAAgAwJ5EAYMKDh8OCgGURB8AwdYBuV8AwdlAyIyBAgQAyKmOERMVGREOAAQMAZ4OAYI
+BBggQHwH4jgEBhAIGChIfAgIAHxAQHgGSAYVeEQH4XwGeCAgAyNYBkgHgTwECAMiijAwAySSB+Mg
+Bh5AIBAIAwR3B0EGBAZyAwNgAwLoOERcVFxABrhEfEREAHhERAdCBghAQEBEOAZIBwF4AwN4AyJA
+B+RABlhcREQ8AAbvRAA4AwP4OAAEBwEDAohESFBgUEhEAyJ1AyN4RGxUBh9EAERkVEwGqAZGAwRY
+AwVIREQDIlAGSEgGmEADA/gDI9YQEAMCYAaoB8MoBkhUBwEoB+EoECgGKAaOBiB4AwLpQHgAOAMj
+kDgAAAMC9gQAADgIBwI4AAYlA0rv/DADRR0GGgQ8RDwABjQDA+gGCEQDAvgEBg4DAuAGSHhAAyJ4
+IHgDInAAAAYQPAQ4QEBwSAcBAANEehgACAAYCAgISDBAQAMD+QaOBlAAAGhUVEQDAnQG6AMCSAMC
+yAADI1p4QAMDSEQ8BAAAWCQgIHAGWEA4BAYYAwJnKAMCnAYuWANCUQME+AfiVHwGSEhIMAMDSAYY
+OBBgAAB4CDBAeAMCoGAgIBgDAngHYzAICAwICDAAKFADRuhsRER8AwPeQEQ4EDBIAwVYDAMF4Ach
+AyMIKAflMAflOCgH5AMkFxAwBiAGqAYgB+MGIAMFCAME8BAGgRgAIAMFCAYHKER8RAMCQGwH4gwA
+fEB4A2KYAHgUfFA8ADxQUHxQUFwAOAAwSAOCOCgH5WAH5TgDBaBgB+UoAwXwAwL9BugH5AAQOEBA
+OBAAGCQgeCAkXABEKBB8ByEAYFBQaFxISAAIFBA4EBBQIBgDBdADIyIQGAfhAwRgGAMGWFADI6kH
+4khoWEgDBSY8AwUeeAMi8DADQiAAA2ISA6N2/AQEB6FASFA4RAgcB+IsVBwEBmADglsGEiRIJAZf
+AEgkAyKuVACoB2SoBySo/FT8B2IDRDAHA/AHpQfjUFBQ0AdhAyK+8AfjAwYQ0BAGkAcGBhAGyNAQ
+8AYkAAYCB+MGJgfjBngDBVgcBpAQEPwDZgwDBhAHggZIAwYYAwUOBpBQUFBcAwNYXAMjtQMC9wbI
+3AboB6HcAwUYBpAGCAaQBhgGkBADBghQUAMGKAMDWAZCAwW7AwNQAwJoBpgDBXAGAnwG11ADB0AD
+JiADBbgGoPwHBQZJB+LgBwUcBwUDBhQAADRISDQDY49wSEhwQHhIA4OpAAB8A8R6eEggECADwtEA
+PANDTwNjYHAGWShQAwKHOBA4A8LZA0IIeAaZOEREKChsADBAIBA4BqkoA4KfA0KIVFQDIvg4QANi
+FwAGaQNjr3gHIwZYEAAGEEAwCDBABgkHoTAIBlEIFANIAlAgBiAAfAdhAwJ3B0IGfwMDjgPmiAcB
+A8SRHAYnBihQAwK9BwFgEAODTQPjNXgDAmgHHwcfBx8HHwcfBx8HHwcfBx8HHwcfBx8HHwcfBx8H
+HwcfBx8HHwcfBx8HHwcfBx8HHwcfBx8HHwcfBx8HHwcfBx8HHwcfBx8HHwcfBx8HHwcfBwM=`;
+
 /// MAME support
 
 class ColecoVisionMAMEPlatform extends BaseMAMEPlatform implements Platform {
@@ -61,6 +286,8 @@ class ColecoVisionMAMEPlatform extends BaseMAMEPlatform implements Platform {
   getDefaultExtension() { return ".c"; };
 }
 
+
 ///
 
-PLATFORMS['coleco'] = ColecoVisionMAMEPlatform;
+PLATFORMS['coleco.mame'] = ColecoVisionMAMEPlatform;
+PLATFORMS['coleco'] = _ColecoVisionPlatform;
diff --git a/src/video/tms9918a.ts b/src/video/tms9918a.ts
index 99e72ce0..39be382e 100644
--- a/src/video/tms9918a.ts
+++ b/src/video/tms9918a.ts
@@ -1,3 +1,4 @@
+'use strict';
 /*
  * js99'er - TI-99/4A emulator written in JavaScript
  *
@@ -9,7 +10,7 @@
  * GNU General Public License v2.0
  */
 
-'use strict';
+ import { hex } from "../util";
 
 enum TMS9918A_Mode {
   GRAPHICS = 0,
@@ -32,6 +33,7 @@ export function TMS9918A(canvas, cru, enableFlicker) {
 
     this.ram = new Uint8Array(16384); // VDP RAM
     this.registers = new Uint8Array(8);
+    this.spriteBuffer = new Uint8Array(256);
     this.addressRegister = null;
     this.statusRegister = null;
 
@@ -178,7 +180,8 @@ TMS9918A.prototype = {
             var y1 = y - vBorder;
             // Pre-process sprites
             if (!textMode) {
-                var spriteBuffer = new Uint8Array(drawWidth);
+                var spriteBuffer = this.spriteBuffer;
+                spriteBuffer.fill(0);
                 var spritesOnLine = 0;
                 var endMarkerFound = false;
                 var spriteAttributeAddr = spriteAttributeTable;
@@ -550,11 +553,11 @@ TMS9918A.prototype = {
     getRegsString: function () {
         var s = "";
         for (var i = 0; i < this.registers.length; i++) {
-            s += "VR" + i + ":" + this.registers[i].toHexByte() + " ";
+            s += "VR" + i + ":" + hex(this.registers[i],2) + " ";
         }
-        s += "\nSIT:" + this.nameTable.toHexWord() + " PDT:" + this.charPatternTable.toHexWord() + " (" + this.patternTableSize().toHexWord() + ")" +
-             " CT:" + this.colorTable.toHexWord() + " (" + this.colorTableSize().toHexWord() + ") SDT:" + this.spritePatternTable.toHexWord() +
-             " SAL:" + this.spriteAttributeTable.toHexWord() + "\nVDP: " + this.addressRegister.toHexWord();
+        s += "\nSIT:" + hex(this.nameTable,4) + " PDT:" + hex(this.charPatternTable,4) + " (" + hex(this.patternTableSize(),4) + ")" +
+             " CT:" + hex(this.colorTable,4) + " (" + hex(this.colorTableSize(),4) + ") SDT:" + hex(this.spritePatternTable,4) +
+             " SAL:" + hex(this.spriteAttributeTable,4) + "\nVDP: " + hex(this.addressRegister,4);
         return s;
     },
 
diff --git a/src/worker/workermain.ts b/src/worker/workermain.ts
index ffeff300..4ffa3492 100644
--- a/src/worker/workermain.ts
+++ b/src/worker/workermain.ts
@@ -111,7 +111,7 @@ var PLATFORM_PARAMS = {
   'nes': { //TODO
     define: '__NES__',
     cfgfile: 'neslib.cfg',
-    libargs: ['crt0.o', 'nes.lib', 
+    libargs: ['crt0.o', 'nes.lib',
       '-D', 'NES_MAPPER=0',
       '-D', 'NES_PRG_BANKS=2',
       '-D', 'NES_CHR_BANKS=0', // TODO: >0 doesn't seem to work
@@ -182,6 +182,8 @@ var PLATFORM_PARAMS = {
   },
 };
 
+PLATFORM_PARAMS['coleco.mame'] = PLATFORM_PARAMS['coleco'];
+
 var _t1;
 function starttime() { _t1 = new Date(); }
 function endtime(msg) { var _t2 = new Date(); console.log(msg, _t2.getTime() - _t1.getTime(), "ms"); }
@@ -1025,7 +1027,7 @@ function linkSDLDZ80(step:BuildStep)
     setupFS(FS, 'sdcc');
     populateFiles(step, FS);
     // TODO: coleco hack so that -u flag works
-    if (step.platform == "coleco") {
+    if (step.platform.startsWith("coleco")) {
       FS.writeFile('crt0.rel', FS.readFile('/share/lib/coleco/crt0.rel', {encoding:'utf8'}));
       FS.writeFile('crt0.lst', '\n'); // TODO: needed so -u flag works
     }
@@ -1046,7 +1048,7 @@ function linkSDLDZ80(step:BuildStep)
     // return unchanged if no files changed
     if (!anyTargetChanged(step, ["main.ihx", "main.noi"]))
       return;
-      
+
     var listings = {};
     for (var fn of step.files) {
       if (fn.endsWith('.lst')) {
@@ -1161,7 +1163,7 @@ function preprocessMCPP(step:BuildStep) {
   // TODO: make configurable by other compilers
   var args = [
     "-D", "__8BITWORKSHOP__",
-    "-D", platform.toUpperCase().replace('-','_'),
+    "-D", platform.toUpperCase().replace(/[-.]/g,'_'),
     "-D", "__SDCC_z80",
     "-I", "/share/include",
     "-Q",