R. T. RUSSELL

BBC BASIC (86) Manual

Introduction

Before You Start

This is a reference manual, it is not intended to teach you BASIC. It gives a summary of the commands and functions plus some hints and tips on their use. It also describes the minor differences between the Acorn 6502 and 8086 versions of BBC BASIC. A general knowledge of BASIC has been assumed.

File handling with BBCBASIC(86) is more flexible than on the BBC Micro and different in approach to most other versions of BASIC. Because of this, BBCBASIC(86) file handling has been covered in some detail.

BBCBASIC(86) is fully configured for the IBM PC and compatibles and all the statements and functions specified for BBC BASIC are available. It has been designed to be as compatible as possible with Version 4 of the 6502 BBC BASIC resident in the BBC Micro Master series. The language syntax is not always completely identical to that of the 6502 version, but in most cases the 8086 version is more tolerant.

The PC version of BBCBASIC(86) is supplied on a floppy disk in a sub-directory called BBCBASIC. It will run under MS-DOS or Microsoft Windows^TM on any PC compatible computer. The name of the file is BBCBASIC.EXE. A run-only version of BBCBASIC(86) is also provided; it is called BBCRUN.EXE. Using this version, you can combine your BBCBASIC(86) program with a run-only version of the interpreter to create a 'bound unit' which may be run directly from the DOS prompt (or from Microsoft Windows^TM) like any other DOS command without it necessarily being apparent that BBCBASIC(86) is involved. See the Annex entitled Using BBCRUN for full details.

Variants of BBCBASIC(86)

Two variants of BBCBASIC(86) are supplied: BBCBASIC and BIGBASIC. The main difference between these variants is that BIGBASIC allows the variables storage area to exceed 64 Kbytes. With this variant of the BBCBASIC(86), a program can store and manipulate, in memory, an amount of data limited only by the RAM capacity of the machine (and the MS-DOS limit of 640Kbytes). Whilst BIGBASIC incorporates all the features of BBCBASIC, it is not 100% compatible. In addition to its minor incompatibilities it:

Runs slightly more slowly than BBCBASIC when performing the same operations.
Uses more code and data memory than BBCBASIC for the same BASIC program.

Consequently, BIGBASIC is in no sense a replacement for BBCBASIC which is a better choice if you do not need more than 64 Kbytes of program and data space.

Naming Conventions

This manual will use the name 'BBCBASIC(86)' when the information given is common to both variants of the BASIC. If the information is specific to the small or large memory variants, the names used will be 'BBCBASIC' and 'BIGBASIC' respectively.

Technicalities

A checksum is performed when either variant of BBCBASIC(86) is loaded. If the file is found to be corrupted, the 'Incompatible hardware or bad file' error message is printed and control is returned to the calling program.

The PC version of BBCBASIC(86) requires about 32 kbytes of code space and a little more than 2 kbytes of data space. When available, BBCBASIC(86) will use a full 64 kbytes for the data segment, giving PAGE (program start address) as &900 and HIMEM as &10000. If less than 64 kbytes are available, HIMEM will be set at a lower value. BBCBASIC(86) releases any memory surplus to its requirements so that other programs can be run from within BBCBASIC(86) by using a 'star' command.

See the Annex entitled BIGBASIC for details of the memory used by that program.

Running BBC BASIC (86)

In the following examples, the system prompts and responses are shown in normal type and your entries are shown in bold type. The examples also assume that BBC BASIC (86) has been installed in directory \BBCBASIC on your hard disk (drive C:).

To run BBCBASIC(86), bring up MS-DOS and type

C:\>CD \BBCBASIC<Enter>
C:\bbcbasic>BBCBASIC<Enter>

(<Enter> means 'press the Enter key')

The system will reply:

PC BBC BASIC Version 4.82 #nnnnnn
by  Richard Russell, Jeffrey Raynor and Brandon Butterworth
(C) Copyright R.T.Russell 2000
>

Alternatively a filename may be given after BBCBASIC, in which case the system proceeds as if a CHAIN "filename" command had been typed after initialisation. A defult extension of .BBC is used if none is supplied. This feature allows BASIC programs to be executed in batch mode.

You may run BBC BASIC (86) from Microsoft Windows^TM by creating a shortcut to the executable C:\BBCBASIC\BBCBASIC.EXE or C:\BBCBASIC\BIGBASIC.EXE; see your Windows documentation for details. BBC BASIC (86) will run 'full screen' or in a Window, however changing from a text mode (e.g. MODE 3) to a graphics mode (e.g. MODE 18) may cause a switch to full-screen mode.

To exit BBC BASIC (86) type

>*BYE<Enter>

>*QUIT<Enter>

CONTENTS

CONTINUE