BBC BASIC for Windows

Introduction and Overview

Introduction to BBC BASIC

BBC BASIC for Windows is an advanced version of BBC BASIC which is fully integrated into the Microsoft Windows™ operating environment (Windows 95, 98, Me, NT4, 2000, XP, Vista, Windows 7, 8/8.1 or 10), providing the programmer with a familiar language but with an up-to-date user interface. It combines the simplicity of BASIC with the sophistication of a modern structured language, allowing you to write utilities and games, use sound and graphics, perform calculations and create complete Windows™ applications.

Getting Started

If you've programmed in BASIC before, but aren't familiar with BBC BASIC, then you might like to dip into some of the tutorial chapters which cover differences between BBC BASIC and other dialects. You can also browse this manual or look up particular features which don't seem to work the way you're used to. The General Information chapter may be of particular interest.

If you are used to earlier versions of BBC BASIC (on the BBC Micro, on the Acorn Archimedes or BBC BASIC (86) on a PC) you may find the user interface somewhat unfamiliar. When you start BBC BASIC for Windows you are presented with a blank editing window into which you can type your BASIC program. Commands such as Load, Save, Chain, New and Renumber are activated by clicking with the mouse on drop-down menus or (in some cases) toolbar buttons, as is usual for Windows programs. There are also keyboard shortcuts for all the commands.

Once you have typed in, or loaded, your BASIC program you can run it by selecting the Run command from the Run menu or by clicking on the button in the toolbar. A second window will open in which appears any output from the BASIC program; error messages also appear here.

If you don't want to run a BASIC program, but simply want to enter commands for immediate execution (rather like a calculator) then select the Immediate Mode command from the Run menu, or click on the button. A second window will open into which you can type BASIC statements, in the same way as you could with previous versions of BBC BASIC.

Overview

A unique feature is the incorporation of an assembler which generates 32-bit code and accepts all 80486 instructions and some Pentium-specific instructions (except special-register and privileged instructions), including floating-point and MMX instructions. You can access the Windows™ Application Program Interface both from BASIC and from assembler code, allowing an experienced programmer to produce sophisticated applications.

The full version provides up to 512 Mbytes of user memory and allows you to create compact (typically less than 100K) stand-alone executable (.EXE) files from your BASIC programs, which will run without BBC BASIC having to be installed and without the need for any special DLLs. You can distribute such executables freely without any royalty being due.

BBC BASIC for Windows is largely compatible with Version 5 of BBC BASIC resident in the Acorn Archimedes and Iyonix computers. It also retains a high degree of compatibility with the BBC Microcomputer, including emulation of the SOUND and ENVELOPE statements, and the MODE 7 (teletext) screen mode.

In addition there are a number of major enhancements over these early versions, including data structures, an EXIT statement, PRIVATE variables, long strings, NUL-terminated strings, event interrupts, an address of operator, byte variables and arrays, a line continuation character, indirect procedure and function calls and improved numeric accuracy.

Running BBC BASIC

• Select it from the Start Menu.

• Double-click on its desktop icon.

• Double-click on BBCWIN6.EXE in File Explorer (usually in C:\Program Files (x86)\BBC BASIC for Windows).

• At a command prompt issue the command BBCWIN6 (assuming that BBCWIN6.EXE is in the current directory or on the PATH).

• Drag the BASIC program and drop it on the BBC BASIC for Windows icon.

• Right-click on the BASIC program and select edit from the list.

• At a command prompt enter the command BBCWIN6 progname where progname is the name of the BASIC program you want to load (assuming that BBCWIN6.EXE is in the current directory or on the PATH).

BBCWIN6.EXE has one optional command-line switch, -c, which automatically invokes the Compile utility:

bbcwin6 -c progname.bbc

Minimum system requirements

• IBM-compatible PC with 80486 or later processor.

• 16 Megabytes or more of Random Access Memory.

• VGA or higher resolution display.

• 6 Megabytes or more of free hard disk space.

• Microsoft Windows™ 95, 98, Me, NT4, 2000, XP, Vista, Windows 7, 8/8.1 or 10.

For the SOUND statement to work correctly, your processor clock speed should be 133 MHz or higher.

Specification

Example programs

Most of these programs will run using the trial version of BBC BASIC for Windows, although (depending on which programs you have run beforehand) you may need to restart the application first to free up memory. A few of them (notably ASMTEST.BBC, DLGEDIT.BBC, SEARCHBBC.BBC, SORTTEST.BBC and the file-handling demonstrations) require more than the 32K of user memory available with that version.

The example programs are located in sub-folders under the following categories:

FILING

GAMES

GENERAL

GRAPHICS

PHYSICS

CRADLE.BBC	A simulation of Newton's Cradle, which demonstrates conservation of energy and momentum.
CRATES.BBC	Simulates crates falling under the influence of gravity and tumbling over each other.
DANGLE.BBC	Simulates a dangling chain, which you can grab with the mouse.
PINBALL.BBC	A working simulation of a pinball table, combining 2D physics with 3D graphics.
PINTOGRAPH.BBC	Simulates a pantograph-like drawing engine made from Meccano™ components.

SOUNDS

TOOLS

WINDOWS

Differences from BBC BASIC (86)

• Line numbers may be omitted, except where they are required as the destination of a GOTO, GOSUB or RESTORE.
• Keywords may optionally be accepted and displayed in lower-case.
• The following BASIC V statements are accepted:
  • CASE... OF... WHEN... OTHERWISE... ENDCASE
  • CIRCLE [FILL] x,y,r
  • ELLIPSE [FILL] x,y,a,b
  • ERROR n, "string"
  • FILL x,y
  • Multi-line IF... THEN... ELSE... ENDIF
  • INSTALL "libfile"
  • LINE x1,y1,x2,y2
  • MOUSE x,y,b
  • MOUSE ON n
  • MOUSE OFF
  • OFF
  • ORIGIN x,y
  • QUIT
  • RECTANGLE [FILL] x,y,dx,dy [TO xnew,ynew]
  • SWAP var,var
  • WHILE... ENDWHILE
• The following BASIC V functions are accepted:
  • DIM(array())
  • DIM(array(), n)
  • GET$#file
  • REPORT$
  • SUM(array())
• The following BASIC V operators are accepted:
  • +=
  • −=
  • <<
  • >>
  • >>>
• The following statements have new forms:
  • BPUT #file, string$
  • COLOUR l,p
  • COLOUR l,r,g,b
  • GCOL c
  • LOCAL array()
  • ON
  • ON CLOSE
  • ON MOUSE
  • ON MOVE
  • ON SYS
  • ON TIME
  • PLOT x,y
  • PLOT 160-207
  • RESTORE ERROR
• You can assign a whole array, or set the elements of an array to constant values:
  • A() = B()
  • A$() = B$()
  • A() = 1,2,3
  • A$() = "one","two","three"
• You can assign to a sub-string:
  • LEFT$(A$,N) = string$
  • MID$(A$,N,M) = string$
  • RIGHT$(A$,N) = string$
• You can access the Windows™ Application Program Interface with the SYS statement.
• You can use binary constants, e.g. %01011111.
• The resident assembler generates 32-bit code and accepts all 80286, 80386 and 80486 instructions (except special-register and privileged instructions). A few Pentium instructions (notably CPUID) are also accepted.

Version 6 changes

BASIC interpreter

• Support for legacy 40-bit (5 byte) floating-point variables has been removed.

• 'Suffixless' variables are always 80-bit (10-byte) numeric variants which can contain either a 64-bit signed integer (a whole number in the range −9,223,372,036,854,775,808 to +9,223,372,036,854,775,807) or an 80-bit long double floating-point value (with a precision of approximately 19 significant figures).

• A new 64-bit signed integer variable type is introduced, which has a %% suffix (for example 'number%%'). This data type can also be used as an array or a structure member.

• Strings are no longer limited to a maximum length of 65,535 characters. A string now has a 32-bit length value, so effectively may be any length, subject only to the amount of available memory (heap).

• The PTR# and EXT# pseudo-variables, which read or write the file pointer and file length respectively, now return or accept 64-bit values, so random-access files are no longer limited to a maximum length of 2 Gbytes.

• The assembler accepts the FCOMI, FCOMIP, FUCOMI and FUCOMIP instructions.

Operating System interface

• The *FLOAT command is extended to accept the parameter 80 in addition to 40 and 64 (i.e. *FLOAT 80). The command affects only the precision with which floating-point values are stored and retrieved using floating-point indirection or in data files (PRINT# and INPUT# statements). For compatibility with earlier versions of BBC BASIC the default is *FLOAT 40.

• A new *HEX command determines whether the hexadecimal conversion (& and ~) and bit-shift (<< and >>) operators treat their operands as 32-bit or 64-bit integers. In the (default) *HEX 32 mode the operators work in a fashion which is compatible with earlier versions of BBC BASIC. In *HEX 64 mode they support 64-bit integers.

• The *FONT command supports the strikeout attribute, signified by the character Q. The strikeout attribute (Q) and the underscore attribute (U) are mutually-exclusive.

Compiler

• A new compiler directive REM!Fast is provided, which can speed up run-time accesses to specified variables, arrays, structures, functions and procedures in the compiled program.

• The manifest embedded in a compiled executable, when the Use Windows XP visual styles option is enabled, includes the necessary identifier to indicate compatibility with Windows 10/11 ™.

Program editor and IDE

• A new menu selection Run... Debug, and associated toolbar button (it looks like a beetle), are provided. The effect is to run the current program but immediately to Pause it, enable Trace mode and open the List Variables window.

• A new toolbar button corresponding to the Step Line menu selection is provided, for the convenience of debugging. It looks like an upside-down version of the eject symbol.

Compatibility considerations

• Variant (suffixless) numeric variables and string variables - and particularly arrays of these data types - use more memory. To accommodate this, the default amount of memory available has been doubled (from 16K to 32K in the trial version, and from 1 Mbyte to 2 Mbytes in the full version) but if your program explicitly allocates more memory by raising HIMEM it is quite likely that you will need to raise it even higher.

• A program will fail if it assumes that, in *FLOAT 64 mode, a 'suffixless' variable or array (for example var) is 64-bits. If such a variable is passed by reference to a Windows™ API function, which requires a parameter of type 'double', a hash suffix character must be added to all occurrences of the variable (for example var#) to restore correct operation. This will not affect compatibility with earlier versions of BBC BASIC for Windows.

• Programs which make assumptions about the size and/or format of data items in memory, for example which calculate an offset into a variant ('suffixless') numeric array or string array, and then access the data using indirection or assembler code, will need to be adapted to take account of the different sizes and formats of those data types.

• Be careful when comparing two numeric values, if one may have suffered a reduction in precision (for example by being stored in memory using floating-point indirection or having been written to and subsequently read from a data file using PRINT# and INPUT#). In earlier versions of BBC BASIC for Windows you could usually assume that no loss of precision would result, and therefore that 'before' and 'after' values could safely be compared for equality. In version 6 this is no longer true, unless you specify *FLOAT 80 mode.

• If you update a file pointer and/or file size in assembler code ("setptr" and "setext" functions respectively) you must modify the code to initialise the edx register to contain the most-significant 32-bits of the required pointer or size (normally that will mean setting it to zero, e.g. xor edx,edx).

• If your program contains assembler code which is activated using the CALL statement, bear in mind that if any parameters passed to the code are 'suffixless' numerics or 'movable' strings the code will receive different 'type' values and data formats. Specifically, a variant numeric will have a type of 10 (74 for an array) and be stored in 10 bytes, and a 'movable' string will have a type of 136 (200 for an array) and have an 8-byte descriptor (32-bit pointer and 32-bit length).

Notices

BBC BASIC for Windows is the Copyright © 2001-2021 of R. T. Russell. It is supplied for use on one computer at a time only. Neither the program nor its accompanying documentation may be copied for simultaneous use by the purchaser nor for use by anyone other than the purchaser.

Schools and colleges are granted permission to reproduce or adapt sections of this manual to support teaching in a classroom context.

The name BBC BASIC is used with the permission of the British Broadcasting Corporation.

The aPLib compression library is used with permission. Copyright © 1998-2014 by Joergen Ibsen, All Rights Reserved.

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