diff --git a/src/view/components/Simulator.tsx b/src/view/components/Simulator.tsx
index a89f1289e..179e16a89 100644
--- a/src/view/components/Simulator.tsx
+++ b/src/view/components/Simulator.tsx
@@ -103,9 +103,17 @@ class Simulator extends React.Component<any, IState> {
   private handleClick(button: HTMLElement, active: boolean) {
     const ButtonA: boolean = button.id.match(/BTN_A/) !== null;
     const ButtonB: boolean = button.id.match(/BTN_B/) !== null;
+    const ButtonAB: boolean = button.id.match(/BTN_AB/) !== null;
     let innerButton;
     let newState;
-    if (ButtonA) {
+    if (ButtonAB) {
+      innerButton = window.document.getElementById("BTN_AB_INNER");
+      newState = {
+        button_a: active,
+        button_b: active
+      };
+      this.setState(newState);
+    } else if (ButtonA) {
       innerButton = window.document.getElementById("BTN_A_INNER");
       newState = {
         button_a: active
diff --git a/src/view/components/cpx/Accessibility_utils.ts b/src/view/components/cpx/Accessibility_utils.ts
index bdd36df64..99becbebd 100644
--- a/src/view/components/cpx/Accessibility_utils.ts
+++ b/src/view/components/cpx/Accessibility_utils.ts
@@ -4,6 +4,16 @@ namespace accessibility {
     elem.setAttribute("focusable", "true");
     elem.setAttribute("tabindex", "0");
   }
+
+  export function setAria(elem: Element, role?: string, label?: string): void {
+    if (role && !elem.hasAttribute("role")) {
+      elem.setAttribute("role", role);
+    }
+
+    if (label && !elem.hasAttribute("aria-label")) {
+      elem.setAttribute("aria-label", label);
+    }
+  }
 }
 
 export default accessibility;
diff --git a/src/view/components/cpx/Cpx.tsx b/src/view/components/cpx/Cpx.tsx
index ad596fd5d..4f3fe3b1e 100644
--- a/src/view/components/cpx/Cpx.tsx
+++ b/src/view/components/cpx/Cpx.tsx
@@ -34,6 +34,39 @@ const Cpx: React.FC<IProps> = props => {
   return CPX_SVG;
 };
 
+const makeButton = (
+  g: SVGElement,
+  left: number,
+  top: number,
+  id: string
+): { outer: SVGElement; inner: SVGElement } => {
+  const buttonCornerRadius = SvgStyle.BUTTON_CORNER_RADIUS;
+  const buttonWidth = SvgStyle.BUTTON_WIDTH;
+  const buttonCircleRadius = SvgStyle.BUTTON_CIRCLE_RADIUS;
+  const btng = svg.child(g, "g", { class: "sim-button-group" });
+  svg.child(btng, "rect", {
+    id: id + "_OUTER",
+    x: left,
+    y: top,
+    rx: buttonCornerRadius,
+    ry: buttonCornerRadius,
+    width: buttonWidth,
+    height: buttonWidth,
+    fill: SvgStyle.BUTTON_OUTER
+  });
+
+  const outer = btng;
+  const inner = svg.child(btng, "circle", {
+    id: id + "_INNER",
+    cx: left + buttonWidth / 2,
+    cy: top + buttonWidth / 2,
+    r: buttonCircleRadius,
+    fill: SvgStyle.BUTTON_NEUTRAL
+  });
+
+  return { outer, inner };
+};
+
 const initSvgStyle = (svgElement: HTMLElement, brightness: number): void => {
   let style: SVGStyleElement = svg.child(
     svgElement,
@@ -49,6 +82,9 @@ const initSvgStyle = (svgElement: HTMLElement, brightness: number): void => {
     {}
   ) as SVGDefsElement;
 
+  let g = svg.createElement("g") as SVGElement;
+  svgElement.appendChild(g);
+
   let glow = svg.child(defs, "filter", {
     id: "filterglow",
     x: "-5%",
@@ -99,6 +135,20 @@ const initSvgStyle = (svgElement: HTMLElement, brightness: number): void => {
     type: "linear",
     slope: brightness
   });
+
+  // BTN A+B
+  const outerBtn = (left: number, top: number, label: string) => {
+    const button = makeButton(g, left, top, "BTN_AB");
+    return button;
+  };
+
+  let ab = outerBtn(165, SvgStyle.MB_HEIGHT - 15, "A+B");
+  let abtext = svg.child(ab.outer, "text", {
+    x: SvgStyle.BUTTON_TEXT_BASELINE,
+    y: SvgStyle.MB_HEIGHT - 18,
+    class: "sim-text"
+  }) as SVGTextElement;
+  abtext.textContent = "A+B";
 };
 
 const updateNeopixels = (props: IProps): void => {
@@ -170,8 +220,8 @@ const changeBrightness = (filterID: string, brightness: number): void => {
 };
 
 const setupButtons = (props: IProps): void => {
-  const outButtons = ["A_OUTER", "B_OUTER"];
-  const inButtons = ["A_INNER", "B_INNER"];
+  const outButtons = ["A_OUTER", "B_OUTER", "AB_OUTER"];
+  const inButtons = ["A_INNER", "B_INNER", "AB_INNER"];
   outButtons.forEach(buttonName => {
     const button = window.document.getElementById("BTN_" + buttonName);
 
@@ -187,9 +237,22 @@ const setupButtons = (props: IProps): void => {
   });
 };
 
+const addButtonLabels = (button: HTMLElement) => {
+  let label = "";
+  if (button.id.match(/AB/) !== null) {
+    label = "A+B";
+  } else if (button.id.match(/A/) !== null) {
+    label = "A";
+  } else if (button.id.match(/B/) !== null) {
+    label = "B";
+  }
+  accessibility.setAria(button, "button", label);
+};
+
 const setupButton = (button: HTMLElement, className: string, props: IProps) => {
   const svgButton = (button as unknown) as SVGElement;
   svg.addClass(svgButton, className);
+  addButtonLabels(button);
   if (className.match(/outer/) !== null) {
     accessibility.makeFocusable(svgButton);
   }
diff --git a/src/view/components/cpx/Cpx_svg_style.tsx b/src/view/components/cpx/Cpx_svg_style.tsx
index 531ef92e0..74b7eb219 100644
--- a/src/view/components/cpx/Cpx_svg_style.tsx
+++ b/src/view/components/cpx/Cpx_svg_style.tsx
@@ -11,6 +11,11 @@ export const RED_LED_ON: string = "#FF7777";
 export const RED_LED_OFF: string = "#FFFFFF";
 export const BUTTON_NEUTRAL: string = "#000000";
 export const BUTTON_PRESSED: string = "#FFA500";
+export const BUTTON_OUTER: string = "#DCDCDC";
+export const BUTTON_CORNER_RADIUS: number = 2;
+export const BUTTON_WIDTH: number = 10;
+export const BUTTON_CIRCLE_RADIUS: number = 3;
+export const BUTTON_TEXT_BASELINE: number = 163;
 
 // Adapted from : https://github.com/microsoft/pxt/blob/master/pxtsim/simlib.ts
 export function rgbToHsl(