jsbeeb - Javascript BBC Micro emulator

By Matt Godbolt, based on Sarah Walker's b-em: huge thanks to her for open sourcing it, and to Richard Talbot-Watkins for his help and support. The Acorn Atom emulation is Andrew Hague's. The cycle-accurate emulation owes a great deal to the fantastic Visual 6502 project, who are well worth a donation. The disc loaded by default is the amazing Elite, made available by Ian Bell.

Source on GitHub. For more on the BBC, and people to talk to about it, try the StarDot forums. Works best in Chrome or Firefox. Icons are from Bootstrap Icons (MIT).

jsbeeb emulates the BBC Micro Model B and Master 128, and the Acorn Atom that came before them. Choose the machine and the keyboard layout in the settings: click the model name on the top bar.

Elite, the classic 3D space trading game, is already in drive 0. Press SHIFT+BREAK (Shift+F12) to boot it. Other discs and tapes load from the media window: click Media on the top bar. Pasting text types it into the BBC.

On a phone or tablet

Tap ⌨ for an on-screen BBC keyboard; BREAK and the function keys are along its top, and its more key brings up the keys that do not fit, such as COPY and TAB.

Playing together

Shared session, in the More menu, lets friends play on one machine, each in their own browser: host it and send round the link.

A BBC keyboard has its symbols in different places from yours. The default Physical layout goes by position: most keys press the BBC key in the same place, so the BBC's : * is the key two to the right of your L. Natural goes by character instead, so what you type is what the BBC gets; it suits typing, and games want Physical or Gaming. Gaming puts the BBC's CAPS LOCK and CTRL on your left Ctrl and Alt, for games that steer with them; jsbeeb's Alt shortcuts still come first. Any key can be remapped from the URL.

On a Mac, hold fn for the function keys. Games there can't use Caps Lock to move or fire, as browsers never report it being let go; the Gaming layout puts the BBC's CAPS LOCK on Ctrl.

BBC and Master keys yours lacks (Physical and Natural layouts)
BBC key	Press
F0	F10
BREAK	F12
COPY	End (on a Mac laptop, fn+→)
SHIFT LOCK	Home
@	` in Physical
_ £	Page Up in Physical; in Natural, ` gives £

Every shortcut is on Alt, so Ctrl stays with the BBC. They work whether the machine is running or not.

Alt-P pauses the machine and Alt-S stops it in the debugger. While it is stopped, these keys work; where two windows offer the same key, the one in front gets it. Each debug window also lists its keys along its bottom.