Glossary

Board — a microcontroller development board (Pico, ESP32, pyboard) with MicroPython installed as its firmware. Chapter 11.

Build / variant — a flavour of a port, compiled with a chosen feature set. This guide's is the unix port's standard variant; sys.implementation reports which one you have (ch. 1).

bytearray — a mutable sequence of bytes; the buffer type you edit in place (ch. 5).

bytes — an immutable sequence of bytes. Indexing it yields integers, in MicroPython and CPython alike (ch. 5).

const — micropython.const(x): declares an integer constant the compiler may substitute inline, saving memory on boards (ch. 6).

CPython — the reference implementation of Python, from python.org; this guide's referee.

Firmware — software installed on a chip as its built-in program. On a board, MicroPython itself is the firmware (ch. 11).

Frozen module — a module compiled into the firmware/binary itself rather than stored as a file; several entries in help('modules') are frozen (ch. 3).

Garbage collector (GC) — the machinery that reclaims memory from objects no longer in use; import gc reports and triggers it (ch. 6).

Heap — the memory Python objects are allocated from. On MicroPython it is a fixed, settable size (-X heapsize= on the unix port) and running out raises MemoryError (ch. 6).

machine module — MicroPython's hardware interface (Pin, I2C, ADC...). Present on the unix port only as a stub without Pin (ch. 8, 11).

MemoryError — the exception raised when the heap cannot satisfy an allocation; catchable, and worth rehearsing for (ch. 6).

MicroPython — an implementation of Python 3 written to fit microcontrollers; a subset of CPython's library with its own additions (ch. 1, 3).

mpy-cross — the cross-compiler that turns .py files into .mpy bytecode files ahead of time, to save memory and startup work on boards (mentioned in ch. 1's build notes in the criteria).

Native emitter — the compiler path behind @micropython.native, which turns a function into machine code (ch. 7).

Port — a build of MicroPython for one platform: unix, rp2 (Pico), esp32, and others (ch. 1).

REPL — the read–eval–print loop; the interactive >>> prompt. It echoes expression values; scripts do not (ch. 2).

Small int — a fixed-width integer type used by constrained builds; past its range a build without big integers cannot go (ch. 4).

Unix port — MicroPython built to run as a program on Linux, macOS, or Windows; this guide's lab bench (ch. 1).

Viper — the typed, stricter dialect behind @micropython.viper, compiled to machine code with raw-integer semantics (ch. 7).