smolBASIC

(formerly known as mi:little coder)

A very simple text-based programming language for the BBC micro:bit, written in Python.

Tell me more, tell me more

smolBASIC could be a child's first text-based programming language, but it's also simple enough students can modify it themselves, for example adding instructions to show more images or access more sensors on the micro:bit or play more sounds. It could be used in KS3 in England to satisfy the requirement to teach a text-based language, and it could be accessible to more students than other, more complex languages.

Its sheer simplicty also allows students to access some of the clarity of thought that comes with learning assembly language or machine code, but without having to learn hexadecimal, binary or memorise op codes.

As a first text-based langauge, it aims to be as simple as possible, so it avoids punctuation like quotation marks around strings or brackets that students find hard to type.

Programs have no line numbers when entered, but lines do have numbers when listed (mainly to allow 'goto' statements to work).

Every instruction takes 1 second to execute. The slow pace allows students to think about how their programs work and what they do.

A student can simply type

heart
pacman
ghost
run

and they have written and executed a text-based program and sequence without worrying about line numbers, capital letters or punctuation.

Despite being so simple, it lets you save smolBASIC programs to the micro:bit's non-volatile memory, so you don't lose your work (if you remember to save it!)

Read my initial blog post and watch the video here: http://www.suppertime.co.uk/blogmywiki/2021/07/simple-text-language/

What's the instruction set?

Enter instructions and they don't run immediately as they would at a BASIC prompt or Python REPL. Instead they get stored in a program, which you then run by typing run

LED display

Show images / icons just by typing their name, eg

heart
happy
sad
confused
meh
angry 
asleep
confused
yes
no
duck
small heart
pacman
ghost
skull
rabbit
diamond
small diamond
star

It's easy for students to add their own image instructions to the language.

Scroll text on the LED display with

scroll hello world

Variables

You can have 26 variables. They have single letter names a - z.

Assign a variable with

a=23

You can get user input using

input b

Assign a random number between 1 and 99 to a variable with

random a 99

Branching and flow control

smolBASIC has a goto instruction:

if a>b goto 6

It supports <, > and = as operators.

Stop a program executing with

stop

Editing and running programs

Delete the current program with new

You can delete line 3 with del 3

Edit line 3 by typing the line number and what you now want it to read, eg

3 happy

Run a program with run

Break out of a program with ctrl-C on the host computer.

Sound

Play note A with

beep A

At the moment no note duration can be set.

Saving and loading programs

Save the current program to non-volatile memory with save

Restore the saved program with load

I think smolBASIC has just enough instructions to be 'Turing complete', but I'm happy to be corrected.

Why 'smolBASIC'?

It's smoller than TinyBASIC.

What you need to run it

• A BBC micro:bit V2 with built-in speaker (alas, it's now not smol enough to run on a V1)
• A micro USB cable
• A computer with either USB serial terminal software or access via Chrome or Edge web browsers to either the online micro:bit Python editor https://python.microbit.org/v/2 or the new alpha editor https://python.microbit.org/v/alpha or an online serial console like https://googlechromelabs.github.io/serial-terminal/

How to start it up

• Flash the .py or .hex file to a BBC micro:bit V2
• Open a serial console, either the REPL in one of the micro:bit Python editors or any other serial console
• Type 'help' and press enter to see a list of instructions
• Type commands and run them!

To-do list

There's lots I could add, but I don't want to add too much - it needs to be super-simple. One thing that certainly must be added is the ability to increment and decrement variables as a way into coding simple loops.

Sample programs

Voting age

0 print enter your age
1 input a
2 b=17
3 if a>b goto 6
4 print you are too young to vote
5 stop
6 print you can vote

Guess the number

0 random a 10
1 print guess my number 1-10
2 input b
3 if a=b goto 6
4 if a>b goto 8
5 if a<b goto 10
6 print correct!
7 stop
8 print too low!
9 goto 1
10 print too high!
11 goto 1