BBC Micro

BBC Micro / Acorn Electron

The Acorn 8-bit systems consist of a 6502-compatible MOS 6510 processor with custom hardware for graphics and simple sound.

Setting up

To set up your , first get the following tools:

• Assembler: ACME, Mads Assembler ( https://mads.atari8.info/ )
• Emulator(s): BeebEm ( http://www.mkw.me.uk/beebem/ )

Memory map

Docs 	Address 	All machines 	BBC Master 128
Page 00 	0000 	Current Language Zero Page 	Master maps main ram even in shadow mode
0090 	Operating System Zero Page
	0100 	Processor Stack
Page 02 	0200 	Operating System Workspace
Page 03 	0300
	0400 	Current Language Workspace
0500
0600
0700
Page 08-0D 	0800 	Sound & Printer Buffer
0900 	RS423, Speech & Tape output Buffer
0A00 	RS423 & Tape input Buffer
0B00 	Function Keys
0C00 	User defined graphics
0D00 	NMI routines (Disk/Econet)
0D9F 	Expander vector set
0DF0 	Paged ROM workspace storage locations
Page 0E-18 	0E00 	USER workspace 	DFS workspace (not Master)
	1900 	
3000 	Screen (Mode 0, 1, 2) 	USER workspace with shadow Mode 128…134
Screen memory is in shadow ram at same addresses as on normal machines
4000 	Screen (Mode 3)
5800 	Screen (Mode 4, 5)
6000 	Screen (Mode 6)
7B00 	Screen (Mode 7)
Paged Rom 	8000 	Paged Roms 	Private Ram
	C000 	OS ROM 	Paged rom workspace
DC00 	MOS CLI Buffer
DD00 	*MOVE workspace
DF00 	MOS private workspace
E000 	OS ROM
FC00 	FRED 1MHz bus
FD00 	JIM 1MHz bus
FE00 	SHIELA I/O Memory
FF00 	OS ROM Vectors

Check out https://mdfs.net/Docs/Comp/BBC/AllMem for a complete memory map

Video display

The BBC Micro / Acorn Electron have the following native video modes:

• Standard text modes
• Bitmap modes
• Teletext / Mode 7 (BBC Micro only)

Sync with frame

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Plot in Bitmap modes

Here is a routine that will allow you to plot a single point in bitmap mode.

To be added

Text mode

To be added

To be added

Sound

To be added soon.

Make some noise

To be added soon.

Additional Resources

• Stardot forums https://stardot.org.uk/forums/