1 Introduction

The BBC BASIC Conversion Unit allows the Acorn ATOM to run programs written in BBC BASIC. It is supplied as an add-on board which fits inside the ATOM and carries the BBC BASIC ROM, a 4K MOS ROM, 2K of extra RAM, sockets for a Utility ROM and a MOS extension ROM, and decoding circuitry. To run BBC BASIC, the ATOM should have the full 12K of RAM and the 6522 VIA.

Once the BBC BASIC expansion is fitted, either of ATOM BASIC and BBC BASIC can be selected from the keyboard by pressing CTRL-BREAK or SHIFT-BREAK respectively. Alternatively, the selection can be made with a soldered link.

The standard ATOM power supply is adequate for the 12 + 12K ATOM with BBC BASIC, 6522, FP ROM and Utility ROM provided that the extra RAM is of the low power type. If any of the printer, Econet and Colour board expansions are fitted, a 5V 3A supply or the internal supply of the ATOM Disc Pack will be required. BBC BASIC on the ATOM cannot use the ATOM DOS, Econet or Colour board, though they can still be used from ATOM BASIC when BBC BASIC is fitted.

The BBC BASIC extension MOS uses the ATOM COS so data saved by *SAVE or BPUT in one mode can be loaded by *LOAD or BGET in the other. The BASIC data transfer functions (SAVE, LOAD, SGET, SPUT, PRINT#, INPUT# etc.) are incompatible.

Next Chapter