A port of BBC Basic V to the Agon Platform in eZ80/ADL mode

A port of BBC Basic for Z80 by R.T.Russell. Modified to run in eZ80/ADL mode on the Agon Platform. This port is targetting to be functionally compatible with BBC Basic V5 for the Z80 as per upstream repo https://github.com/rtrussell/BBCZ80

Status: work in progress

See the issue list for functionality that isn't supported yet.

Installation

Copy the 'bbcbasic.bin' file to the /bin folder of your SD card.

Agon specific

ADVAL channels

ADVAL(0) returns the fire buttons as per the BBC Micro User guide in a 16-bit number, plus some extras: Bits:

• 0 - joystick1 fire button pressed
• 1 - joystick2 fire button pressed
• 2 - joystick1 2nd fire button pressed
• 3 - joystick2 2nd fire button pressed
• 8 - always 1, to indicate virtual BBC Micro ADC channel '1' has completed the ADC conversion.

Examples:

• X=0 no button pressed

• X=1 joystick1 fire button pressed

• X=2 joystick2 fire button pressed

• X=3 both fire buttons pressed

• ADVAL(1) - Returns joystick1 X channel as virtual ADC value (0 = left, 32768 center, 65520 right)

• ADVAL(2) - Returns joystick1 Y channel as virtual ADC value (0 = down, 32768 center, 65520 up)

• ADVAL(3) - Returns joystick2 X channel as virtual ADC value

• ADVAL(4) - Returns joystick2 Y channel as virtual ADC value

ADVAL(5) - Returns all digital joystick pins as a single 16bit number (1 = on, 0 = off)

• 15 - joystick1 2nd fire button
• 14 - joystick2 2nd fire button
• 13 - joystick1 fire button
• 12 - joystick2 fire button
• 11 - not used
• 10 - not used
• 09 - not used
• 08 - not used
• 07 - joystick1 right
• 06 - joystick2 right
• 05 - joystick1 left
• 04 - joystick2 left
• 03 - joystick1 down
• 02 - joystick2 down
• 01 - joystick1 up
• 00 - joystick2 up

Other ADVAL channel values are ignored and return 0

Building

Building from source requires the installation of the AgonDev Toolchain Clone the repository, run 'make' and the resulting binary can be found in the project ./bin folder.

history/changes

• The project is originally forked from https://github.com/rtrussell/BBCZ80.
• With changes by Dean Netherton to port to ADL mode running on the eZ80 CPU module for RC2014/RCBus kits.
• It has utilised some of changes done by Dean Belfield (https://github.com/breakintoprogram/agon-bbc-basic-adl) in his original ADL port for the Agon platform.
• With changes to the original code to optimize for performance using the ez80 MLT instruction where possible
• With changes to the original code to allow automatic loading/chaining of a file on the Agon CLI

All original copyrights/licenses etc as per individual contributors.