R. T. RUSSELL

BBC BASIC (Z80) Manual

Operating System Interface

Introduction

As with the BBC micro computer, the star (*) commands provide access to the operating system. Since the BBC operating system is completely different to CP/M-80 there are a number of differences in the star commands.

File Specifiers

File specifiers must comply with the standard CP/M-80 conventions.

[drive:]filename.extension
drive: The single letter name (A to P) of the drive where the file will be found. The colon is mandatory. If the drive name is omitted, the currently logged-on drive is assumed.

filename The name of the file. The length of the name must not exceed 8 characters.

extension The optional extension of the file. If an extension is used it must be separated from the filename by a full-stop. If the extension is omitted, .BBC is assumed.

Drives A: to P: are accepted in file specifications. Filenames in star commands may optionally be enclosed in quotes; unmatched quotes will cause a 'Bad string' error. The standard CP/M-80 'wild-cards' may be used when an ambiguous file specifier is acceptable.

? Allow any single character in this position. If this is used as the last character in the name, a null character will be accepted.

* Allow any character (including a null) from the position of the '*' to the end of the name or extension.

Symbols

The following symbols and abbreviations are used as part of the explanation of the operating system commands.

{} The enclosed items may be repeated 0 or more times.

[] The items enclosed are optional, they may occur zero or one time.

num A numeric constant.

str A string constant.

<num> A numeric variable.

<str> A string variable.

afsp An ambiguous file specifier.

ufsp An unambiguous file specifier.

d: A disk drive name.

dir A directory name.

Accessing Star Commands

The star commands may be accessed directly or via the OSCLI statement. The two examples below both access the BYE command.

*BYE

OSCLI("BYE")

Syntax

A star command must be the last (or only) command on a program line and its argument may not be a variable. If you need to use one of these commands with a variable as the argument, use the OSCLI statement. Examples of the use of the OSCLI statement are given below in the Resident Star Commands sub-section.

Case Conversion

Star commands and their associated qualifiers are converted from lower-case to upper-case if necessary. For example, *era wombat is converted to *ERA WOMBAT. This is in keeping with the general CP/M-80 philosophy and the BBC Micro's machine operating system (MOS).

Special Characters

Control characters, lower-case characters, DEL and quotation marks may be incorporated in filenames by using the 'escape' character '|'.

|A gives ^A.

|a gives lower-case A.

|? gives Del.

|" gives the quote marks ".

|| gives the escape character |.

|! sets bit 7 of the following character.

CONTENTS

CONTINUE

`drive:`	The single letter name (A to P) of the drive where the file will be found. The colon is mandatory. If the drive name is omitted, the currently logged-on drive is assumed.
`filename`	The name of the file. The length of the name must not exceed 8 characters.
`extension`	The optional extension of the file. If an extension is used it must be separated from the filename by a full-stop. If the extension is omitted, .BBC is assumed.

`?`	Allow any single character in this position. If this is used as the last character in the name, a null character will be accepted.
`*`	Allow any character (including a null) from the position of the '*' to the end of the name or extension.

{}	The enclosed items may be repeated 0 or more times.
[]	The items enclosed are optional, they may occur zero or one time.
num	A numeric constant.
str	A string constant.
<num>	A numeric variable.
<str>	A string variable.
afsp	An ambiguous file specifier.
ufsp	An unambiguous file specifier.
d:	A disk drive name.
dir	A directory name.

\|A	gives ^A.
\|a	gives lower-case A.
\|?	gives Del.
\|"	gives the quote marks ".
\|\|	gives the escape character \|.
\|!	sets bit 7 of the following character.