Atari ST series - Page 397

In order to maintain upward compatibility, pro
grammers are cautioned to use only documented system
variables, and to avoid writing directly to the hardware. All
RAM below location 2048 ($800) is reserved for use by the
system. This is protected memory, and may only be accessed
from supervisor mode. Attempts to read or write to these lo
cations from user mode will cause a bus error (two mush
rooms).
Table K-l. 68000 Exception Vectors
Vector
Number Address Vector
0 $000 Initial Supervisor Stack Pointer on Reset
1 $004 Initial Program Counter on Reset
2 $008 Bus Error
3 $00C Address Error
4 $010 Illegal Instruction Error
5 $014 Divide by 0
6 $018 CHK Instruction
7 $01C TRAPV Instruction
8 $020 Privilege Violation
9 $024 Trace
10 $028 Opcode 1010 emulation (Line A routines
11 $02C Opcode 1111 emulation (Line F-used by AES)
12-23 $030-$05C Reserved by Motorola
24 $060 Spurious Interrupt
Table K-2. Auto-Vector Interrupts
Vector
Number Address Vector
25 $064 Level 1 Interrupt: (used if Hblank enabled)
26 $068 Level 2 Interrupt: Horizontal blank sync
(Hblank)
27 $06C Level 3 Interrupt: Normal processor interrupt
level
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