Topic       : TOS - The Operating System
Author      : 
Version     : tos.hyp (December 19, 2008)
Subject     : Programmieren/Atari
Nodes       : 3010
Index Size  : 93790
HCP-Version : 5
Compiled on : Atari
@charset    : atarist
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View Ref-File4.18.1  Blitmode                                                   TOS

 Name:         »blitter mode« - Blitter-chip configuration

 Opcode:       64

 Syntax:       int16_t Blitmode( int16_t mode );

 Description:  Blitmode is an XBIOS routine to switch on the blitter 
               or to verify its existence. If the parameter mode has 
               the value -1 then one obtains the state of the blitter 
               chip. All other values configure the blitter:

                 Bit  Description 
                   0  0 = Blitter off 
                      1 = Blitter on 
                1-14  Reserved 
                  15  Must always be 0 

               Note: According to Atari the function may be used 
               without checking the TOS version (although it is not 
               present in TOS 1.0, for instance). This is possible due 
               to a side-effect in the dispatcher of the XBIOS. 
               However, it is better not to rely on this, as the 
               corresponding trap may be diverted by other programs, 
               so that the correct value may not be returned.

 Return value: The function returns the properties of the blitter chip 
               by the set bits:

                Bit  Meaning 
                 0   0: Blitter off 
                     1: Blitter on 
 
                 1   0: Blitter not present 
                     1: Blitter present 
 
                15   Always 0 

               All further bits are reserved.

 Availability: Officially this function is present only as of TOS 
               Version 1.02.

 Group:        Special commands

 See Also:     Binding