JSAcorn - Javascript Acorn Atom and BBC Micro emulator

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By Matt Godbolt. Based on Sarah Walker's b-em emulator. Huge thanks to her for open sourcing her code. Big thanks too to Richard Talbot-Watkins for his help and support. The disc loaded up by default is the amazing Elite (thanks to Ian Bell for making it available).

Source is on GitHub. Works best in Chrome or Firefox.

Cycle-accurate emulation greatly helped by the fantastic Visual 6502 Project. Consider donating to them if you enjoy this stuff as much as I do!

I f you're looking for more information on the BBC or to find like-minded people to chat about the hardware or software, check out the StarDot forums.

The Acorn Atom emulator is by Andrew Hague and makes heavy use of the 6502 emulator in jsbeeb. Many thanks to David Banks for open sourcing the Atomulator emulator. Also thanks to the Acorn Atom source on Mame and Phil's Place for unwittingly helping me with jsatom. The MMC loaded by default is the amazing Acorn Atom Software Archive created by David Banks.

Source for Acorn Atom is on GitHub.

This is an emulator for the BBC Micro Model B, a popular home computer in the UK in the 1980s.

The default disc image is Elite - a pioneering 3D space trading game. To boot discs on the BBC, one would press SHIFT and BREAK. The keyboard of the BBC is slightly different from a modern PC, notably in the placement of the symbol characters. Also, the current keyboard layout is optimized for a US keyboard; I am working on improving this situation.

It also includes an emulator for its predecessor, the Acorn Atom.

Handy key mappings

BBC	PC	OSX
F0	F10	F10
BREAK	F12	Right ⌘ + F12
COPY	End	Right ⌘ + F11
* :	TODO	TODO
Debug	Ctrl-Home	TODO

For the Acorn Atom, the default SDCard is the Acorn Atom Software Archive. This also requires a modified Atom OS rom and it will automatically boot. To avoid booting press SHIFT and BREAK. To disable MMC support altogether press CTRL and BREAK. Like the BBC, the keyboard of the Acorn Atom is slightly different from a modern PC.

Handy Acorn Atom key mappings

NOTE: The SHIFT and CTRL key are exchanged on the Acorn Atom natural layout.

ATOM	PC	OSX
BREAK	F12	F12
COPY	TAB	TAB
REPT	RIGHT_SHIFT	RIGHT_SHIFT
LOCK	F1	F1
CTRL	LEFT_SHIFT	LEFT_SHIFT
SHIFT	CTRL	CTRL
* :	+ =	+ =
Debug	Ctrl-Home	TODO

6845 state

6845 regs

System VIA

User VIA