Difference between revisions of "OSBYTE &00"

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[[Category:OSBYTE]]
 
[[Category:OSBYTE]]
===OSBYTE &00 (0) - Identify Host/Operating System===
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{{PageTitle|OSBYTE &00 (0) - Identify Host/Operating System}}
 
<div class="mw-widebody">
 
<div class="mw-widebody">
 
  On entry, X=0  - Generate error number 247 giving host and OS type
 
  On entry, X=0  - Generate error number 247 giving host and OS type
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  On exit,  X=host/OS type:
 
  On exit,  X=host/OS type:
    :d.dir.file/ext          dir/file.ext            :d.dir.file/ext        d:file.ext
 
 
   0 Electron/Communicator  8 UNIX-type system
 
   0 Electron/Communicator  8 UNIX-type system
 
   1 BBC                    9 6809/6309 system    17 6809/6309 system
 
   1 BBC                    9 6809/6309 system    17 6809/6309 system
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   6 Arthur or RISC OS                                                30 Amstrad CPC
 
   6 Arthur or RISC OS                                                30 Amstrad CPC
 
   7 Springboard                                                      31 Sinclair ZX Spectrum
 
   7 Springboard                                                      31 Sinclair ZX Spectrum
 +
    :d.dir.file/ext          dir/file.ext            :d.dir.file/ext    d:file.ext
 
   
 
   
    d:\dir\file.ext
 
 
  32 IBM PC-type system (DOS, Windows, etc.)
 
  32 IBM PC-type system (DOS, Windows, etc.)
 
  39 6809/6309 system
 
  39 6809/6309 system
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    d:\dir\file.ext
 
</div>
 
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80x86 BBC BASIC running on DOS and Windows returns 32 as a side effect
 
80x86 BBC BASIC running on DOS and Windows returns 32 as a side effect
 
of reading the character under the cursor. Properly written code that
 
of reading the character under the cursor. Properly written code that
calls OSBYTE 0 will know to do so when there is a space under the cursor.
+
calls OSBYTE 0 will know to do so in a manner that ensures this occurs.
 
Normally this just means calling OSBYTE 0 at program startup before
 
Normally this just means calling OSBYTE 0 at program startup before
 
outputting anything.
 
outputting anything.
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* [[Multiplatform programming]]
 
* [[Multiplatform programming]]
  
 +
----
 
[[User:Jgharston|Jgharston]] 22:41, 6 September 2007 (BST)
 
[[User:Jgharston|Jgharston]] 22:41, 6 September 2007 (BST)
 
[[User:Jgharston|Jgharston]] ([[User talk:Jgharston|talk]]) 06:35, 12 April 2020 (CEST)
 
[[User:Jgharston|Jgharston]] ([[User talk:Jgharston|talk]]) 06:35, 12 April 2020 (CEST)

Latest revision as of 20:59, 21 January 2021

OSBYTE &00 (0) - Identify Host/Operating System
On entry, X=0  - Generate error number 247 giving host and OS type
          X<>0 - Return host/OS in X

On exit,  X=host/OS type:
 0 Electron/Communicator  8 UNIX-type system
 1 BBC                    9 6809/6309 system     17 6809/6309 system
 2 BBC B+                10 MacOS X
 3 Master 128
 4 Master ET                                                         28 Commodore 64/128
 5 Master Compact                                                    29 Texas Instruments calculator
 6 Arthur or RISC OS                                                 30 Amstrad CPC
 7 Springboard                                                       31 Sinclair ZX Spectrum
   :d.dir.file/ext          dir/file.ext            :d.dir.file/ext     d:file.ext

32 IBM PC-type system (DOS, Windows, etc.)
39 6809/6309 system
   d:\dir\file.ext

Implementations

Early documentation refers to OSBYTE 0 as returning the OS version. As more systems were developed, it became more correct to refer to it returning a value indicating the host. For example, code running on a second processor will always be told what the I/O host is regardless of what the host is and what the second processor is.

80x86 BBC BASIC running on DOS and Windows returns 32 as a side effect of reading the character under the cursor. Properly written code that calls OSBYTE 0 will know to do so in a manner that ensures this occurs. Normally this just means calling OSBYTE 0 at program startup before outputting anything.

Platform capabilities

Over time the OSBYTE 0 return value has evolved to become a bitmap representing the capabilities of the host system, primarily of the file system structure.

  • %000x0xxx Filenames are directory.filename/extension, eg BBC, RISC OS
  • %000x1xxx Filenames are directory/filename.extension, eg Unix, CP/M
  • %nnnxxxxx Filenames are directory\filename.extension, eg DOS, Windows

This can also be represented as:

  • %000x0xxx Directory seperator is '.'
  • %000x1xxx Directory seperator is '/'
  • %nnnxxxxx Directory seperator is '\'
  • %000x0xxx Extension seperator is '/'
  • %nnnxnxxx Extension seperator is '.'

This allow programs to use code similar to the following:

  A%=0:X%=1:os%=((USR&FFF4)AND&FF00)DIV256
  d$=".":s$="/":IF(os%AND-24):d$="/":s$=".":IF(os%AND-32):d$="\"
  filename$=dir$+d$+name$+s$+ext$

See also


Jgharston 22:41, 6 September 2007 (BST) Jgharston (talk) 06:35, 12 April 2020 (CEST)