Editing Macintosh Toolbox (section)

=== PowerPC Mixed-Mode Implementation ===
PowerPC Macs lack illegal instruction traps, requiring a different approach:

'''Universal Procedure Pointers (UPPs):'''
<pre>
TYPE RoutineDescriptor = RECORD
    goMixedModeTrap:    INTEGER;       {$AAFE}
    version:            BYTE;          {7 for PowerPC}
    flags:              BYTE;          {ISA and calling conventions}
    reserved:           LONGINT;       
    reserved2:          BYTE;
    selectorCount:      BYTE;
    routineCount:       INTEGER;
    {Array of RoutineRecords follows}
END;
</pre>

'''Mixed-Mode Switch Process:'''
# Code calls UPP thinking it's a routine address
# UPP contains $AAFE trap at offset 0
# 68k emulator intercepts trap
# Mixed-Mode Manager examines descriptor
# Routes to native PPC or emulated 68k code
# Handles calling convention translation

'''Native Implementation Flags:'''
The Power Mac ROM includes tables indicating native implementations:
* '''$FFF00000''': Native trap table base
* '''Bit vector''': 1 bit per trap (1=native, 0=emulated)
* '''Jump table''': Direct PPC routine addresses