diff --git a/cmds/cmds.ts b/cmds/cmds.ts
index bec3277e..a39d285a 100644
--- a/cmds/cmds.ts
+++ b/cmds/cmds.ts
@@ -1,6 +1,8 @@
 /// <reference path="../node_modules/pxt-core/typings/globals/node/index.d.ts"/>
 /// <reference path="../node_modules/pxt-core/built/pxtlib.d.ts" />
 
+import * as fs from 'fs';
+
 require("./editor")
 
 declare namespace pxt.editor {
@@ -9,4 +11,9 @@ declare namespace pxt.editor {
 
 export function deployCoreAsync(resp: pxtc.CompileResult) {
     return pxt.editor.deployCoreAsync(resp, process.env["PXT_SERIAL"] ? false : true)
+        .then(() => {
+            fs.writeFileSync("built/full-" + pxtc.BINARY_UF2, resp.outfiles[pxtc.BINARY_UF2], {
+                encoding: "base64"
+            })
+        })
 }
diff --git a/editor/extension.ts b/editor/extension.ts
index dd65cf74..e00cd2d4 100644
--- a/editor/extension.ts
+++ b/editor/extension.ts
@@ -7,6 +7,8 @@ namespace pxt {
 eval("if (typeof process === 'object' && process + '' === '[object process]') pxt = global.pxt")
 
 namespace pxt.editor {
+    import UF2 = pxtc.UF2;
+
     // this comes from aux/pxt.lms
     const rbfTemplate = `
 4c45474f580000006d000100000000001c000000000000000e000000821b038405018130813e8053
@@ -22,12 +24,15 @@ namespace pxt.editor {
             })
     }
 
+    let noHID = false
+
     let initPromise: Promise<Ev3Wrapper>
     function initAsync() {
         if (!initPromise)
             initPromise = hf2Async()
                 .catch(err => {
                     initPromise = null
+                    noHID = true
                     return Promise.reject(err)
                 })
         return initPromise
@@ -35,34 +40,73 @@ namespace pxt.editor {
 
     export function deployCoreAsync(resp: pxtc.CompileResult, isCli = false) {
         let w: Ev3Wrapper
-        let elfPath = "../prjs/BrkProg_SAVE/binary.elf"
-        let rbfPath = "../prjs/BrkProg_SAVE/pxt0.rbf"
+
+        let filename = resp.downloadFileBaseName
+
+        let fspath = "../prjs/BrkProg_SAVE/"
+
+        let elfPath = fspath + filename + ".elf"
+        let rbfPath = fspath + filename + ".rbf"
+
+        let rbfHex = rbfTemplate
+            .replace(/\s+/g, "")
+            .replace("XX", U.toHex(U.stringToUint8Array(elfPath)))
+        let rbfBIN = U.fromHex(rbfHex)
+        HF2.write16(rbfBIN, 4, rbfBIN.length)
+
+        let origElfUF2 = UF2.parseFile(U.stringToUint8Array(atob(resp.outfiles[pxt.outputName()])))
+
+        let mkFile = (ext: string, data: Uint8Array = null) => {
+            let f = UF2.newBlockFile()
+            f.filename = "Projects/" + filename + ext
+            if (data)
+                UF2.writeBytes(f, 0, data)
+            return f
+        }
+
+        let elfUF2 = mkFile(".elf")
+        for (let b of origElfUF2) {
+            UF2.writeBytes(elfUF2, b.targetAddr, b.data)
+        }
+
+        let r = UF2.concatFiles([elfUF2, mkFile(".rbf", rbfBIN)])
+        let data = UF2.serializeFile(r)
+
+        resp.outfiles[pxtc.BINARY_UF2] = btoa(data)
+
+        let saveUF2Async = () => {
+            if (isCli || !pxt.commands.saveOnlyAsync) {
+                return Promise.resolve()
+            } else {
+                return pxt.commands.saveOnlyAsync(resp)
+            }
+        }
+
+        if (noHID) return saveUF2Async()
+
         return initAsync()
             .then(w_ => {
                 w = w_
                 if (w.isStreaming)
                     U.userError("please stop the program first")
                 return w.stopAsync()
-            }).then(() => {
-                return w.rmAsync(elfPath)
-            }).then(() => {
-                let f = U.stringToUint8Array(atob(resp.outfiles[pxt.outputName()]))
-                return w.flashAsync(elfPath, f)
-            }).then(() => {
-                let rbfHex = rbfTemplate
-                    .replace(/\s+/g, "")
-                    .replace("XX", U.toHex(U.stringToUint8Array(elfPath)))
-                let rbf = U.fromHex(rbfHex)
-                HF2.write16(rbf, 4, rbf.length)
-                return w.flashAsync(rbfPath, rbf)
-            }).then(() => {
-                return w.runAsync(rbfPath)
-            }).then(() => {
+            })
+            .then(() => w.rmAsync(elfPath))
+            .then(() => w.flashAsync(elfPath, UF2.readBytes(origElfUF2, 0, origElfUF2.length * 256)))
+            .then(() => w.flashAsync(rbfPath, rbfBIN))
+            .then(() => w.runAsync(rbfPath))
+            .then(() => {
                 if (isCli)
                     return w.disconnectAsync()
                 else
                     return Promise.resolve()
-                    //return Promise.delay(1000).then(() => w.dmesgAsync())
+                //return Promise.delay(1000).then(() => w.dmesgAsync())
+            }).catch(e => {
+                // if we failed to initalize, retry
+                if (noHID)
+                    return saveUF2Async()
+                else
+                    return Promise.reject(e)
             })
     }
 
diff --git a/pxtarget.json b/pxtarget.json
index 3da4de30..5cc36a87 100644
--- a/pxtarget.json
+++ b/pxtarget.json
@@ -33,6 +33,7 @@
     },
     "compile": {
         "isNative": true,
+        "useUF2": true,
         "useELF": true,
         "hasHex": true,
         "deployDrives": ".*",