diff --git a/.vscode/settings.json b/.vscode/settings.json
index 30bf8c2d3..fa0a10487 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -8,4 +8,4 @@
     },
     // Turn off tsc task auto detection since we have the necessary tasks as npm scripts
     "typescript.tsc.autoDetect": "off"
-}
\ No newline at end of file
+}
diff --git a/gulpfile.js b/gulpfile.js
index 3c106798d..5a4a494a8 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -1,135 +1,138 @@
-/*---------------------------------------------------------------------------------------------
- *  Copyright (c) Microsoft Corporation. All rights reserved.
- *  Licensed under the MIT License. See License.txt in the project root for license information.
- *--------------------------------------------------------------------------------------------*/
-
-const gulp = require("gulp");
-
-const ts = require("gulp-typescript");
-const sourcemaps = require("gulp-sourcemaps");
-const typescript = require("typescript");
-const del = require("del");
-const es = require("event-stream");
-const vsce = require("vsce");
-const nls = require("vscode-nls-dev");
-
-const tsProject = ts.createProject("./tsconfig.json", { typescript });
-
-const inlineMap = true;
-const inlineSource = false;
-const outDest = "out";
-
-// A list of all locales supported by VSCode can be found here: https://code.visualstudio.com/docs/getstarted/locales
-const languages = [{ folderName: "en", id: "en" }];
-
-gulp.task("clean", () => {
-  return del(
-    [
-      "out/*",
-      "package.nls.*.json",
-      "../../dist/*0.0.0-UNTRACKEDVERSION.vsix"
-    ],
-    { force: true }
-  );
-});
-
-const pythonToMove = [
-  "./src/adafruit_circuitplayground/*.*",
-  "./src/*.py",
-  "./src/requirements.txt",
-];
-
-gulp.task("python-compile", () => {
-  // the base option sets the relative root for the set of files,
-  // preserving the folder structure
-  return gulp.src(pythonToMove, { base: "./src/" }).pipe(gulp.dest("out"));
-});
-
-gulp.task("internal-compile", () => {
-  return compile(false);
-});
-
-gulp.task("internal-nls-compile", () => {
-  return compile(true);
-});
-
-gulp.task("add-locales", () => {
-  return gulp
-    .src(["package.nls.json"])
-    .pipe(nls.createAdditionalLanguageFiles(languages, "locales"))
-    .pipe(gulp.dest("."));
-});
-
-gulp.task("vsce:publish", () => {
-  return vsce.publish();
-});
-
-gulp.task("vsce:package", () => {
-  return vsce.createVSIX({
-    packagePath: "../../dist/deviceSimulatorExpress-0.0.0-UNTRACKEDVERSION.vsix"
-  });
-});
-
-gulp.task(
-  "compile",
-  gulp.series("clean", "internal-compile", "python-compile", callback => {
-    callback();
-  })
-);
-
-gulp.task(
-  "build",
-  gulp.series(
-    "clean",
-    "internal-nls-compile",
-    "python-compile",
-    "add-locales",
-    callback => {
-      callback();
-    }
-  )
-);
-
-gulp.task(
-  "publish",
-  gulp.series("compile", "vsce:publish", callback => {
-    callback();
-  })
-);
-
-gulp.task(
-  "package",
-  gulp.series("compile", "vsce:package", callback => {
-    callback();
-  })
-);
-
-//---- internal
-
-function compile(buildNls) {
-  var r = tsProject
-    .src()
-    .pipe(sourcemaps.init())
-    .pipe(tsProject())
-    .js.pipe(buildNls ? nls.rewriteLocalizeCalls() : es.through())
-    .pipe(
-      buildNls
-        ? nls.createAdditionalLanguageFiles(languages, "locales", "out")
-        : es.through()
-    );
-
-  if (inlineMap && inlineSource) {
-    r = r.pipe(sourcemaps.write());
-  } else {
-    r = r.pipe(
-      sourcemaps.write("../out", {
-        // no inlined source
-        includeContent: inlineSource,
-        // Return relative source map root directories per file.
-        sourceRoot: "../src"
-      })
-    );
-  }
-
-  return r.pipe(gulp.dest(outDest));
-}
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+const gulp = require("gulp");
+
+const ts = require("gulp-typescript");
+const sourcemaps = require("gulp-sourcemaps");
+const typescript = require("typescript");
+const del = require("del");
+const es = require("event-stream");
+const vsce = require("vsce");
+const nls = require("vscode-nls-dev");
+
+const tsProject = ts.createProject("./tsconfig.json", { typescript });
+
+const inlineMap = true;
+const inlineSource = false;
+const outDest = "out";
+
+// A list of all locales supported by VSCode can be found here: https://code.visualstudio.com/docs/getstarted/locales
+const languages = [{ folderName: "en", id: "en" }];
+
+gulp.task("clean", () => {
+    return del(
+        [
+            "out/*",
+            "package.nls.*.json",
+            "../../dist/*0.0.0-UNTRACKEDVERSION.vsix",
+        ],
+        { force: true }
+    );
+});
+
+const pythonToMove = [
+    "./src/adafruit_circuitplayground/*.*",
+    "./src/microbit/*.*",
+    "./src/microbit/!(test)/**/*",
+    "./src/*.py",
+    "./src/requirements.txt",
+];
+
+gulp.task("python-compile", () => {
+    // the base option sets the relative root for the set of files,
+    // preserving the folder structure
+    return gulp.src(pythonToMove, { base: "./src/" }).pipe(gulp.dest("out"));
+});
+
+gulp.task("internal-compile", () => {
+    return compile(false);
+});
+
+gulp.task("internal-nls-compile", () => {
+    return compile(true);
+});
+
+gulp.task("add-locales", () => {
+    return gulp
+        .src(["package.nls.json"])
+        .pipe(nls.createAdditionalLanguageFiles(languages, "locales"))
+        .pipe(gulp.dest("."));
+});
+
+gulp.task("vsce:publish", () => {
+    return vsce.publish();
+});
+
+gulp.task("vsce:package", () => {
+    return vsce.createVSIX({
+        packagePath:
+            "../../dist/deviceSimulatorExpress-0.0.0-UNTRACKEDVERSION.vsix",
+    });
+});
+
+gulp.task(
+    "compile",
+    gulp.series("clean", "internal-compile", "python-compile", callback => {
+        callback();
+    })
+);
+
+gulp.task(
+    "build",
+    gulp.series(
+        "clean",
+        "internal-nls-compile",
+        "python-compile",
+        "add-locales",
+        callback => {
+            callback();
+        }
+    )
+);
+
+gulp.task(
+    "publish",
+    gulp.series("compile", "vsce:publish", callback => {
+        callback();
+    })
+);
+
+gulp.task(
+    "package",
+    gulp.series("compile", "vsce:package", callback => {
+        callback();
+    })
+);
+
+//---- internal
+
+function compile(buildNls) {
+    var r = tsProject
+        .src()
+        .pipe(sourcemaps.init())
+        .pipe(tsProject())
+        .js.pipe(buildNls ? nls.rewriteLocalizeCalls() : es.through())
+        .pipe(
+            buildNls
+                ? nls.createAdditionalLanguageFiles(languages, "locales", "out")
+                : es.through()
+        );
+
+    if (inlineMap && inlineSource) {
+        r = r.pipe(sourcemaps.write());
+    } else {
+        r = r.pipe(
+            sourcemaps.write("../out", {
+                // no inlined source
+                includeContent: inlineSource,
+                // Return relative source map root directories per file.
+                sourceRoot: "../src",
+            })
+        );
+    }
+
+    return r.pipe(gulp.dest(outDest));
+}
diff --git a/src/microbit/__init__.py b/src/microbit/__init__.py
new file mode 100644
index 000000000..a0d5418e9
--- /dev/null
+++ b/src/microbit/__init__.py
@@ -0,0 +1 @@
+from .shim import *
diff --git a/src/microbit/model/button.py b/src/microbit/model/button.py
new file mode 100644
index 000000000..54a60e8a4
--- /dev/null
+++ b/src/microbit/model/button.py
@@ -0,0 +1,27 @@
+class Button:
+    # The implementation is based off of https://github.com/bbcmicrobit/micropython/blob/master/docs/button.rst.
+    def __init__(self):
+        self.__pressed = False
+        self.__presses = 0
+        self.__prev_pressed = False
+
+    def is_pressed(self):
+        return self.__pressed
+
+    def was_pressed(self):
+        res = self.__prev_pressed
+        self.__prev_pressed = False
+        return res
+
+    def get_presses(self):
+        res = self.__presses
+        self.__presses = 0
+        return res
+
+    def __press_down(self):
+        self.__pressed = True
+        self.__prev_pressed = True
+        self.__presses += 1
+
+    def __release(self):
+        self.__pressed = False
diff --git a/src/microbit/model/microbit_model.py b/src/microbit/model/microbit_model.py
new file mode 100644
index 000000000..f8e2572da
--- /dev/null
+++ b/src/microbit/model/microbit_model.py
@@ -0,0 +1,21 @@
+import time
+
+from .button import Button
+
+
+class MicrobitModel:
+    def __init__(self):
+        # State in the Python process
+        self.button_a = Button()
+        self.button_b = Button()
+        self.__start_time = time.time()
+
+    def sleep(self, n):
+        time.sleep(n / 1000)
+
+    def running_time(self):
+        print(f"time. time: {time.time()}")
+        return time.time() - self.__start_time
+
+
+mb = MicrobitModel()
diff --git a/src/microbit/shim.py b/src/microbit/shim.py
new file mode 100644
index 000000000..ac8f544f0
--- /dev/null
+++ b/src/microbit/shim.py
@@ -0,0 +1,9 @@
+from .model import microbit_model
+
+
+def sleep(n):
+    microbit_model.mb.sleep(n)
+
+
+def running_time():
+    microbit_model.mb.running_time()
diff --git a/src/microbit/test/__init__.py b/src/microbit/test/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/src/microbit/test/test_button.py b/src/microbit/test/test_button.py
new file mode 100644
index 000000000..aee9cbb43
--- /dev/null
+++ b/src/microbit/test/test_button.py
@@ -0,0 +1,46 @@
+import pytest
+from ..model.button import Button
+
+
+class TestButton(object):
+    def setup_method(self):
+        self.button = Button()
+
+    def test_press_down(self):
+        self.button._Button__press_down()
+        assert self.button._Button__presses == 1
+        assert self.button._Button__pressed
+        assert self.button._Button__prev_pressed
+        self.button._Button__press_down()
+        assert self.button._Button__presses == 2
+        assert self.button._Button__pressed
+        assert self.button._Button__prev_pressed
+
+    def test_release(self):
+        self.button._Button__pressed = True
+        self.button._Button__prev_pressed = False
+        self.button._Button__release()
+        assert not self.button._Button__pressed
+
+    def test_is_pressed(self):
+        assert not self.button.is_pressed()
+        self.button._Button__press_down()
+        assert self.button.is_pressed()
+
+    def test_was_pressed(self):
+        assert not self.button.was_pressed()
+        self.button._Button__press_down()
+        self.button._Button__release()
+        assert self.button.was_pressed()
+        # Button resets __prev_pressed after was_pressed() is called.
+        assert not self.button.was_pressed()
+
+    @pytest.mark.parametrize("presses", [1, 2, 4])
+    def test_get_presses(self, presses):
+        assert 0 == self.button.get_presses()
+        for i in range(presses):
+            self.button._Button__press_down()
+            self.button._Button__release()
+        assert presses == self.button.get_presses()
+        # Presses is reset to 0 after get_presses() is called.
+        assert 0 == self.button.get_presses()
diff --git a/src/microbit/test/test_microbit_model.py b/src/microbit/test/test_microbit_model.py
new file mode 100644
index 000000000..e37df6019
--- /dev/null
+++ b/src/microbit/test/test_microbit_model.py
@@ -0,0 +1,24 @@
+import time
+
+import pytest
+from unittest import mock
+from ..model.microbit_model import MicrobitModel
+
+
+class TestMicrobitModel(object):
+    def setup_method(self):
+        self.mb = MicrobitModel()
+
+    @pytest.mark.parametrize("value", [9, 30, 1999])
+    def test_sleep(self, value):
+        time.sleep = mock.Mock()
+        self.mb.sleep(value)
+        time.sleep.assert_called_with(value / 1000)
+
+    def test_running_time(self):
+        mock_start_time = 10
+        mock_end_time = 300
+        self.mb._MicrobitModel__start_time = mock_start_time
+        time.time = mock.MagicMock(return_value=mock_end_time)
+        print(time.time())
+        assert mock_end_time - mock_start_time == pytest.approx(self.mb.running_time())
diff --git a/src/microbit/test/test_shim.py b/src/microbit/test/test_shim.py
new file mode 100644
index 000000000..68853ec9b
--- /dev/null
+++ b/src/microbit/test/test_shim.py
@@ -0,0 +1,19 @@
+import time
+
+import pytest
+from unittest import mock
+from .. import shim
+from ..model import microbit_model
+
+
+class TestShim(object):
+    def test_sleep(self):
+        milliseconds = 100
+        microbit_model.mb.sleep = mock.Mock()
+        shim.sleep(milliseconds)
+        microbit_model.mb.sleep.assert_called_with(milliseconds)
+
+    def test_running_time(self):
+        microbit_model.mb.running_time = mock.Mock()
+        shim.running_time()
+        microbit_model.mb.running_time.assert_called_once()