Topic       : Pure C Library Documentation
Author      : John Kormylo
Version     : LIB.HYP 1.0
Subject     : Documentation/Pure C Library
Nodes       : 1309
Index Size  : 32068
HCP-Version : 3
Compiled on : Atari
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@lang       : en
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View Ref-File[ BIOS Functions ]

Bconin        Bcostat       Getmpb        Rwabs
Bconout       Drvmap        Kbshift       Setexc
Bconstat      Getbpb        Mediach       Tickcal

BIOS functions are used for device handlers, and are not intended for
user level I/O.  In fact, the GEMDOS specification is that BIOS
functions be accessable only in Supervisor Mode (fortunately, that
is not the case on the Atari).

BIOS functions are implemented using the TRAP #13 instruction.
Arguments and the BIOS Opcode are passed on the stack, and the
return value will be in register D0.  One can also use bios().

The BIOS TRAP handler is re-entrant to three levels.  For some
functions it copies the arguments to the supervisor stack then uses
a jump vector to perform the operation.  In Supervisor Mode one
can usually bypass the TRAP handler.

See also GEMDOS, XBIOS and MiNT.