They may be commercial or produced by hobbyists they could be open source or propriety and they might be supplied as a PCB, a kit, fully built or anywhere in between! Homepage of B-EM - a freeware BBC Micro Emulator for DOS. I don't use a Mac so I can't really recommend any emulators, but here are what are generally considered the best Mac BBC Emulators: For MacOS 9: ElectrEm is an emulator of the Acorn Electron, an 8bit microcomputer first launched in 1983 that was once the fourth best selling in the UK market. Kieran had mentioned his interest in the 6502 Apple source code for Prince Of Persia, and expressed some mad ideas to get it working on the BBC Micro, which seemed like crazy talk back then since the two machines are similar in some ways but very different in others. Note thatb Elite - The New Kind is a recent PC implementation of Elite pretty true to the original BBC version. In fact it is quite good at pretending to be a Commodore 64 or BBC micro through software emulation.
BBC Micro (1) ColecoVision (1) And best of all, this software is completely free and open-source. So the Python APIs will look exactly the same, the microbit, radio, speech, music modules, etc.