Concise Atari ST 68000 Programmer's Reference Guide
The following tables present the system variables in low supervisor space $0 to $7FF (0 to 2047):
Exception vectors
| 0 | $000 | Reset | Initial SSP value |
| 4 | $004 | Initialise PC | Initial PC address |
| 8 | $008 | Bus Error | Dump state and terminate routine pointer |
| 12 | $00C | Illegal instruction | |
| 16 | $010 | Address error | |
| 20 | $014 | Divide by zero | Pointer to an RTE |
| 24 | $018 | CHK instruction | Dump state and terminate routine pointer |
| 28 | $01C | Trap instruction | |
| 32 | $020 | Privilege violation | |
| 36 | $024 | Trace mode | |
| 40 | $028 | Line 1010 | A-line routine pointer |
| 44 | $02C | Line 1011 | Used by AES |
| ... | Unassigned | ||
| 52 | $034 | Unit interrupt vector | Coprocessor protocol violation (MC68020) |
| 56 | $038 | Unit interrupt vector | Format error (MC68020) |
| 60 | $03C | Unit interrupt vector | Uninitialized interrupt vector |
| 64 | $040 | Unassigned | Unassigned |
| 60 | $03C | Unit interrupt vector | |
| ... | Reserved | ||
| 96 | $060 | Spurious interrupt | (Hacked to level 3) |
| 100 | $064 | Interrupt level 1 | (Used if user wants Hblanks) |
| 104 | $068 | Interrupt level 2 | Horizontal blank sync. (Hblank) |
| 108 | $06C | Interrupt level 3 | Normal processor interrupt level |
| 112 | $070 | Interrupt level 4 | Vertical blank sync. (Vblank) |
| 116 | $074 | Interrupt level 5 | |
| 120 | $078 | Interrupt level 6 | MK68901 MFP interrupts |
| 124 | $07C | Interrupt level 7 | Non maskable interrupt |
| 128 | $080 | Trap #0 vector | |
| 132 | $084 | Trap #1 vector | GEM DOS interface calls |
| 136 | $088 | Trap #2 vector | Extended DOS calls |
| 140 | $08C | Trap #3 vector | |
| ... | |||
| 176 | $0B0 | Trap #12 vector | |
| 180 | $0B4 | Trap #13 vector | GEM BIOS calls |
| 184 | $0B8 | Trap #14 vector | Atari extended BIOS calls |
| 188 | $0BC | Trap #15 vector | |
| 192 | $0C0 | Unassigned | Reserved |
| ... | |||
| 252 | $0FC | Unassigned |
