pxt-calliope/docs/about.md

![](/static/mb/device/pano.jpg)

# About

### @description A Blocks / Javascript code editor for the micro:bit, a pocket-size computer with 5x5 display, sensors and Bluetooth.

The [BBC micro:bit](https://microbit.org) is a [pocket-size computer](/device) with a 5x5 display of 25 LEDs, Bluetooth and sensors that can be programmed by anyone. The BBC micro:bit was made possible by many [partners](https://www.microbit.co.uk/partners).

The micro:bit provides an easy and fun introduction to programming and making – switch on, program it to do something fun – wear it, customize it.
Just like Arduino, the micro:bit can be connected to and interact with sensors, displays, and other devices. 

* [Read the docs](/docs)

## [Hardware: The Device](/device)

The BBC micro:bit is packaged with sensors, radio and other goodies. Learn about the [hardware components](/device) of the micro:bit to make the most of it!

### ~ hint

**Looking to buy a micro:bit?** See the [list of resellers](https://microbit.org/resellers).

### ~

## Programming: [Blocks](/blocks) or [JavaScript](/javascript)

You can program the micro:bit using [Blocks](/blocks) or [JavaScript](/javascript) in your web browser via the [micro:bit APIs](/reference):

```block
input.onButtonPressed(Button.A, () => {
    basic.showString("Hi!");
})
```
```typescript
input.onButtonPressed(Button.A, () => {
    basic.showString("Hi!");
})
```

The editor work in [most modern browsers](/browsers), work [offline](/offline) once loaded and do not require any installation. 

## [Compile and Flash: Your Program!](/device/usb)

When you have your code ready, you connect your micro:bit to a computer via a USB cable, so it appears as a mounted drive (named MICROBIT). 

Compilation to ARM thumb machine code from [Blocks](/blocks) or [JavaScript](/javascript) happens in the browser. You save the ARM binary 
program to a file, which you then copy to the micro:bit drive, which flashes the micro:bit device with the new program.

## Simulator: Test Your Code

You can run your code using the micro:bit simulator, all within the confines of a web browser. 
The simulator has support for the LED screen, buttons, as well as compass, accelerometer, and digital I/O pins.

```sim
basic.forever(() => {
  basic.showString("Hi!");
})
input.onButtonPressed(Button.A, () => {
    led.stopAnimation();
    basic.showLeds(`
. . . . .
. # . # .
. . . . .
# . . . #
. # # # .`);
});
input.onButtonPressed(Button.B, () => {
    led.stopAnimation();
    basic.showLeds(`
. # . # .
# . # . #
# . . . #
. # . # .
. . # . .`);
});
```

## C++ Runtime

The [C++ micro:bit runtime](http://lancaster-university.github.io/microbit-docs/), created at [Lancaster University](http://www.lancaster.ac.uk/), provides access to the hardware functions of the micro:bit, 
as well as a set of helper functions (such as displaying a number/image/string on the LED screen). 

The [micro:bit library](/reference) mirrors the functions of the C++ library. 
When code is compiled to ARM machine code, the calls to JavaScript micro:bit functions are replaced with calls to the corresponding C++ functions.

## [Command Line Tools](/cli)

Looking to use pxt.microbit.org in your favorite editor? Install the [command line tools](/cli) and get rolling!

## [Packages](/packages)

Create, edit and distribute your own blocks and JavaScript using [packages](/packages). Packages are hosted on GitHub and may be written
using C++, JavaScript and/or ARM thumb.

## [Open Source](/open-source)

The code for the micro:bit is [open source](/open-source) on GitHub. Contributors are welcome!