BBC BASIC (Z80) v5 is an implementation of the BBC BASIC programming language for the Z80 CPU. It is largely compatible with Acorn's ARM BASIC V but with a few language extensions based on features of 'BBC BASIC for Windows' and 'BBC BASIC for SDL 2.0'. These extensions include the EXIT statement, the address-of operator (^) and byte (unsigned 8-bit) variables and arrays (& suffix character).
More details of the features added in version 5.00 can be found in the file WHATSNEW.TXT.
The files in green constitute the generic BBC BASIC interpreter which is shared by all the editions, it (just!) fits in 16 Kbytes so could be held in a ROM of this size. The files in the blue box are used to build the generic CP/M edition. The files in the red box are used to build the Acorn Z80 Second Processor edition.
Note that the name 'BBC BASIC' is used by permission of the British Broadcasting Corporation and is not transferrable to a derived or forked work.