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   Snapshot date: 2021-11-28
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*/

==== Table of Contents ====

[[#bbc_basic|BBC BASIC]]

[[#implementing_bbc_basic_on_rienk_koolstar_s_sbc-2g-512|Implementing BBC BASIC on Rienk Koolstar's sbc-2g-512]]

[[#other_versions_of_z80_basic_around_the_web|Other versions of Z80 BASIC around the web:]]

[[#resources|Resources]]

[[#porting|Porting]]

[[#bbc_basic_disassembly|BBC BASIC Disassembly]]

====== BBC BASIC ======

===== Implementing BBC BASIC on Rienk Koolstar's sbc-2g-512 =====

Richard Russell maintains a [[http://www.bbcbasic.co.uk/index.html|website]] providing a number of different versions of BASIC which have compatibility with the original BBC Micro 6502 BASIC and Jonathon Harston has [[http://mdfs.net/Software/BBCBasic/|documented]] over 30 platforms which have implemented BBC BASIC on them.

It was [[http://www.benryves.com/projects/z80computer/|Ben Ryve's homebew Z80 Computer]] implementation that drew my attention to the existence of a Z80 version of BBC BASIC.

A limiting factor around the BBC BASIC ROM is that no source code has been published. However, tools and documentation exists to relocate and expand this system.

==== Other versions of Z80 BASIC around the web: ====

Grant Searle's implementation of NASCOM BASIC 4.7

[[builderpages:b1ackmai1er:sbc-2g-512|[[builderpages:b1ackmai1er:sbc-2g-512]]

ZX Spectrum BASIC ROM

Another version of BASIC that I found particularly interesting is Dr Andy Wright's ZX Spectrum BASIC ROM which has published source code and designed to work in a system with paged ROM addressing system. [[https://github.com/simonowen/samrom|Source code can be found here.]] Other source code for Sinclair and Spectrum ROMs [[https://www.tablix.org/~avian/spectrum/rom/|can be found here.]]

Tiny BASIC

Doug Gabbard at [[http://retrodepot.net/|retrodepot.net]] has updated and implemented Li-Chen Wangs' Tiny Basic and the source code is available [[http://retrodepot.net/?p=424|here.]]

===== Resources =====

R.T. Russell Z80 CPM: http://www.rtrussell.co.uk/bbcbasic/z80basic.html

Z80 CP/M Manual: http://www.bbcbasic.co.uk/bbcbasic/mancpm/index.html

J.G Harston Z80 porting tool: http://mdfs.net/Software/BBCBasic/Z80/port.htm

===== Porting =====

Two versions of Z80 BBC BASIC are available as porting contenders

^              ^Advantages                                                   ^Disadvantages                                                     ^
|Z80 BBC BASIC |Can set ROM and RAM start address using relocation tool.     |Hard coded reserved RAM area at FF80-FFFF for legacy BBC interface|
|CP/M Z80 BASIC|Set up to use CP/M calls for which code is already available.|Fixed, non-relocatable start address. Designed to be run in RAM.  |

J.G Harston port.zip contains the following files

<code code>
BBC0100 - Object code

PortZ80 - Documentation

Relocate - BASIC program to relocate the BBC0100 Object code
</code>

NOTE: The Relocate program in this archive needs to be run under the windows trial version of BBC BASIC. Or use this ASCII text version:

[[https://retrobrewcomputers.org/lib/exe/fetch.php?media=playground:b1ackmai1er:bbcbasic:relocate.zip|:playground:b1ackmai1er:bbcbasic:relocate.zip]]

Memory map:

^          ^Header^Prog Code^Scratch^Workspace  ^Lowest PAGE^highest HIMEM^OSCLI^BRKV ^
|BBC BASIC |&0100 |&0200-   |&34EE  |&3500-&37FF|&3800      |?            |&FFF7|&FFFA|
|SBC-2G-512|&0100 |&0200-   |&FF88  |&4000-&42FF|&4300      |&FF80        |?    |?    |

&0100-&01FF needs to contain the initialization for the board and a jump table for the minimum set of functions required for BBC BASIC to communicate.

The Bbcdist.mac file provides the example code for this area.

\\

===== BBC BASIC Disassembly =====