diff --git a/src/common/baseplatform.ts b/src/common/baseplatform.ts
index 5248f69b..39200ab3 100644
--- a/src/common/baseplatform.ts
+++ b/src/common/baseplatform.ts
@@ -2,7 +2,7 @@
 import { RAM, RasterVideo, KeyFlags, dumpRAM, AnimationTimer, setKeyboardFromMap, padBytes, ControllerPoller } from "./emu";
 import { hex, printFlags, invertMap, getBasePlatform } from "./util";
 import { CodeAnalyzer } from "./analysis";
-import { Segment } from "./workertypes";
+import { Segment, FileData } from "./workertypes";
 import { disassemble6502 } from "./cpu/disasm6502";
 import { disassembleZ80 } from "./cpu/disasmz80";
 import { Z80 } from "./cpu/ZilogZ80";
@@ -80,6 +80,7 @@ export interface Platform {
   resume() : void;
   loadROM(title:string, rom:any); // TODO: Uint8Array
   loadBIOS?(title:string, rom:Uint8Array);
+  getROMExtension?(rom:FileData) : string;
 
   loadState?(state : EmuState) : void;
   saveState?() : EmuState;
diff --git a/src/ide/ui.ts b/src/ide/ui.ts
index 26628007..3923dc66 100644
--- a/src/ide/ui.ts
+++ b/src/ide/ui.ts
@@ -880,12 +880,15 @@ function _downloadROMImage(e) {
     alertError("Please finish compiling with no errors before downloading ROM.");
     return true;
   }
+  var prefix = getFilenamePrefix(getCurrentMainFilename());
   if (current_output instanceof Uint8Array) {
     var blob = new Blob([current_output], {type: "application/octet-stream"});
-    saveAs(blob, getCurrentMainFilename()+".rom");
+    var suffix = (platform.getROMExtension && platform.getROMExtension(current_output)) 
+      || "-" + getBasePlatform(platform_id) + ".bin";
+    saveAs(blob, prefix + suffix);
   } else {
     var blob = new Blob([(<VerilogOutput>current_output).code], {type: "text/plain"});
-    saveAs(blob, getCurrentMainFilename()+".js");
+    saveAs(blob, prefix + ".js");
   }
 }
 
@@ -905,7 +908,7 @@ function _downloadProjectZipFile(e) {
       }
     });
     zip.generateAsync({type:"blob"}).then( (content) => {
-      saveAs(content, getCurrentMainFilename() + ".zip");
+      saveAs(content, getCurrentMainFilename() + "-" + getBasePlatform(platform_id) + ".zip");
     });
   });
 }
@@ -923,7 +926,7 @@ function _downloadAllFilesZipFile(e) {
       })).then(() => {
         return zip.generateAsync({type:"blob"});
       }).then( (content) => {
-        return saveAs(content, platform_id + "-all.zip");
+        return saveAs(content, getBasePlatform(platform_id) + "-all.zip");
       });
     });
   });
diff --git a/src/machine/sms.ts b/src/machine/sms.ts
index 4b21297c..9b119816 100644
--- a/src/machine/sms.ts
+++ b/src/machine/sms.ts
@@ -50,7 +50,7 @@ export class SG1000 extends BaseZ80VDPBasedMachine {
   
    read = newAddressDecoder([
      [0xc000, 0xffff,  0x3ff, (a) => { return this.ram[a]; }],
-     [0x0000, 0xbfff, 0xffff, (a) => { return this.rom[a]; }],
+     [0x0000, 0xbfff, 0xffff, (a) => { return this.rom && this.rom[a]; }],
    ]);
    write = newAddressDecoder([
      [0xc000, 0xffff,  0x3ff, (a,v) => { this.ram[a] = v; }],
@@ -141,7 +141,7 @@ export class SMS extends SG1000 {
   
   getPagedROM(a:number, reg:number) {
     //if (!(a&0xff)) console.log(hex(a), reg, this.pagingRegisters[reg], this.romPageMask);
-    return this.rom[a + ((this.pagingRegisters[reg] & this.romPageMask) << 14)]; // * $4000
+    return this.rom && this.rom[a + ((this.pagingRegisters[reg] & this.romPageMask) << 14)]; // * $4000
   }
 
  read = newAddressDecoder([
diff --git a/src/platform/apple2.ts b/src/platform/apple2.ts
index 2474baf5..f80fc38f 100644
--- a/src/platform/apple2.ts
+++ b/src/platform/apple2.ts
@@ -76,6 +76,10 @@ class NewApple2Platform extends Base6502MachinePlatform<AppleII> implements Plat
       {name:'I/O',start:0xc000,size:0x1000,type:'io'},
       {name:'ROM',start:0xd000,size:0x3000-6,type:'rom'},
   ] } };
+  getROMExtension(rom:Uint8Array) {
+    if (rom && rom.length == 35*16*256) return ".dsk"; // DSK image
+    return ".bin";
+  };
 }
 
 PLATFORMS['apple2.mame'] = Apple2MAMEPlatform;
diff --git a/src/platform/atari7800.ts b/src/platform/atari7800.ts
index 56f20fcf..5764fe3a 100644
--- a/src/platform/atari7800.ts
+++ b/src/platform/atari7800.ts
@@ -26,6 +26,7 @@ class Atari7800Platform extends Base6502MachinePlatform<Atari7800> implements Pl
       {name:'RAM',start:0x1800,size:0x1000,type:'ram'}, // TODO: shadow ram
       {name:'Cartridge ROM',start:0x4000,size:0xc000,type:'rom'},
   ] } };
+  getROMExtension() { return ".a78"; }
 }
 
 ///
diff --git a/src/platform/c64.ts b/src/platform/c64.ts
index 60d2f808..df894651 100644
--- a/src/platform/c64.ts
+++ b/src/platform/c64.ts
@@ -65,6 +65,13 @@ class C64WASMPlatform extends Base6502MachinePlatform<C64_WASMMachine> implement
   showHelp() {
     window.open("https://sta.c64.org/cbm64mem.html", "_help");
   }
+  getROMExtension(rom:Uint8Array) { 
+    /*
+    if (rom && rom[0] == 0x00 && rom[1] == 0x80 && rom[2+4] == 0xc3 && rom[2+5] == 0xc2) return ".crt";
+    */
+    if (rom && rom[0] == 0x01 && rom[1] == 0x08) return ".prg";
+    else return ".bin";
+  }
 }
 
 PLATFORMS['c64'] = C64WASMPlatform;
diff --git a/src/platform/nes.ts b/src/platform/nes.ts
index 738b9a8b..024e1b15 100644
--- a/src/platform/nes.ts
+++ b/src/platform/nes.ts
@@ -264,7 +264,9 @@ class JSNESPlatform extends Base6502Platform implements Platform, Probeable {
   getOriginPC() {	// TODO: is actually NMI
     return (this.readAddress(0xfffa) | (this.readAddress(0xfffb) << 8)) & 0xffff;
   }
-  getDefaultExtension() { return ".c"; };
+  getDefaultExtension() { return ".c"; }
+
+  getROMExtension() { return ".nes"; }
 
   reset() {
     //this.nes.cpu.reset(); // doesn't work right, crashes
diff --git a/src/platform/vcs.ts b/src/platform/vcs.ts
index 162da99f..f6b98c6d 100644
--- a/src/platform/vcs.ts
+++ b/src/platform/vcs.ts
@@ -248,7 +248,9 @@ class VCSPlatform extends BasePlatform {
     if (fn.endsWith(".bb") || fn.endsWith(".bas")) return "bataribasic";
     return "dasm";
   }
-  getDefaultExtension() { return ".a"; };
+  getDefaultExtension() { return ".a"; }
+
+  getROMExtension() { return ".a26"; }
 
   getDebugCategories() {
     return ['CPU','Stack','PIA','TIA'];
diff --git a/src/platform/x86.ts b/src/platform/x86.ts
index f2b09304..2fae9a83 100644
--- a/src/platform/x86.ts
+++ b/src/platform/x86.ts
@@ -159,6 +159,10 @@ class X86PCPlatform implements Platform {
         {name:'BIOS Expansions',start:0xc8000,size:0x28000,type:'rom'},
         {name:'PC BIOS',start:0xf0000,size:0x10000,type:'rom'},
     ] } };
-  }
+
+    getROMExtension(rom : Uint8Array) {
+        return ".exe";
+    }
+}
 
 PLATFORMS['x86'] = X86PCPlatform;
diff --git a/src/platform/zmachine.ts b/src/platform/zmachine.ts
index 98e1f848..973ef34d 100644
--- a/src/platform/zmachine.ts
+++ b/src/platform/zmachine.ts
@@ -809,6 +809,10 @@ class ZmachinePlatform implements Platform {
         this.reset();
     }
 
+    getROMExtension() {
+        return ".z" + (this.zvm.version || 5);
+    }
+
     reset(): void {
         if (this.zfile == null) return;
         this.zvm = new ZVM();
diff --git a/test/cli/testplatforms.js b/test/cli/testplatforms.js
index 43829529..faee75e9 100644
--- a/test/cli/testplatforms.js
+++ b/test/cli/testplatforms.js
@@ -178,6 +178,7 @@ async function testPlatform(platid, romname, maxframes, callback) {
       assert.ok(dinfo && dinfo.length > 0, dcat + " empty");
       assert.ok(dinfo.length < 80*24, dcat + " too long");
       assert.ok(dinfo.indexOf('undefined') < 0, dcat + " undefined");
+      assert.ok(dinfo.indexOf('Display On:  false') < 0, dcat + " display off");
     }
     if (lastrastervideo) {
       var png = new PNG({width:lastrastervideo.width, height:lastrastervideo.height});
@@ -190,6 +191,9 @@ async function testPlatform(platid, romname, maxframes, callback) {
         fs.writeFileSync("./test/output/"+platid+"-"+romname+".png", pngbuffer);
       } catch (e) { console.log(e) }
     }
+    // misc
+    assert.ok(platform.getDefaultExtension().startsWith('.'));
+    if (platform.getROMExtension) assert.ok(platform.getROMExtension().startsWith("."));
     return platform;
 }
 
@@ -308,6 +312,13 @@ describe('Platform Replay', () => {
       }
     });
   });
+  it('Should run sms-sms-libcv', async () => {
+    var platform = await testPlatform('sms-sms-libcv', 'climber.c-sms-sms-libcv.rom', 200, (platform, frameno) => {
+      if (frameno == 122) {
+        keycallback(Keys.RIGHT.c, Keys.VK_RIGHT.c, 1);
+      }
+    });
+  });
   it('Should run atari7800', async () => {
     var platform = await testPlatform('atari7800', 'sprites.dasm.rom', 92, (platform, frameno) => {
       if (frameno == 62) {
diff --git a/test/roms/sms-sms-libcv/climber.c-sms-sms-libcv.rom b/test/roms/sms-sms-libcv/climber.c-sms-sms-libcv.rom
new file mode 100644
index 00000000..92ff1705
Binary files /dev/null and b/test/roms/sms-sms-libcv/climber.c-sms-sms-libcv.rom differ