68k vector table

The vector table consists of a 256 bytes long vector list specific to the 68k.

Each vector is a 32-bit address, meaning the table holds 64 vectors. Each entry is used by the 68k in precise cases.

All bootable 68k programs must have a vector table at their very beginning. The system ROM and games have their own.

Is $C00426 an universal BIOS call for a complete reset ?

Stack frames

See 68k exception handling.

Format A

Offset from SP	Size	Value
+0	Word	Flags: Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Def 0:Write 1:Read 0:Instruction Function code
+2	Longword	Access address
+6	Word	IR
+8	Word	SR
+10	Longword	PC

Format B

Offset from SP	Size	Value
+0	Word	SR
+2	Longword	PC

Vector list

Vector #	Address	Exception name	Trigger condition	Stack frame
0	000000	Reset SP	Not really a vector. Used to initialize the stack pointer.
1	000004	Reset PC	Reset/startup
2	000008	Bus error	Bus cycle couldn't complete properly.	A
3	00000C	Address error	Misaligned (odd) word or longword memory access.	A
4	000010	Illegal instruction	Tried executing an invalid opcode.	B
5	000014	Division by zero	DIVUed or DIVSed by zero.	B
6	000018	CHK instruction	CHK resulted in "out of bounds".	B
7	00001C	TRAPV instruction	TRAPV with overflow flag set.	B
8	000020	Privilege violation	Use of privileged instruction. Never happens on the NeoGeo since the 68k always runs in supervisor mode.	B
9	000024	Trace	After each executed instruction when 68k is in trace mode (debugger function).	B
10	000028	Unimplemented instruction (line A)	Used to implement 680xx instructions in software. Not used on the NeoGeo.	B
11	00002C	Unimplemented instruction (line F)	Used to implement 680xx instructions in software. Not used on the NeoGeo.	B
12	000030	Reserved/Unused on 68000
13	000034
14	000038
15	00003C	Uninitialized interrupt vector	Default vector used by uninitialized peripherals.	B?
16	000040	Reserved
17	000044
18	000048
19	00004C
20	000050
21	000054		Normally reserved but used on the NeoGeo CD as vectored interrupt (sector transfer complete ?).
22	000058		Normally reserved but used on the NeoGeo CD as vectored interrupt (initiates CD drive command/status exchange).
23	00005C		Normally reserved but used on the NeoGeo CD as vectored interrupt (retrieves word value from $FF010C).
24	000060	Spurious interrupt	No acknowledge from hardware.
25	000064	Level 1 interrupt autovector	V-Blank (MVS) / Timer interrupt (CD).
26	000068	Level 2 interrupt autovector	Timer interrupt (MVS) / V-Blank (CD).
27	00006C	Level 3 interrupt autovector	Cold boot.
28	000070	Level 4 interrupt autovector	Not used on the NeoGeo.
29	000074	Level 5 interrupt autovector	Not used on the NeoGeo.
30	000078	Level 6 interrupt autovector	Not used on the NeoGeo.
31	00007C	Level 7 interrupt autovector	Not used on the NeoGeo.
32	000080	TRAP #0~15	TRAP instructions.	2
48~63	0000C0~0000FC	Reserved/Unused on 68000
64~255	000100~0003FF	User interrupt vectors

Templates

For cartridge systems

    org  $0
    dc.l $0010F300            ; Initial SP
    dc.l $00C00402            ; Initial PC
    dc.l $00C00408            ; Bus error
    dc.l $00C0040E            ; Address error
    dc.l $00C0040E            ; Illegal Instruction
    dc.l $0000034C            ; Divide by 0
    dc.l $0000034E            ; CHK Instruction
    dc.l $0000034E            ; TRAPV Instruction
    dc.l $00C0041A            ; Privilege Violation
    dc.l $00C00420            ; Trace
    dc.l $0000034E,$0000034E  ; Emu
    dc.l $00C00426,$00C00426,$00C00426  ; Reserved
    dc.l $00C0042C            ; Uninit. Int. Vector.
    dc.l $00C00426,$00C00426,$00C00426,$00C00426  ; Reserved
    dc.l $00C00426,$00C00426,$00C00426,$00C00426  ; Reserved
    dc.l $00C00432            ; Spurious Interrupt
    dc.l VBlank               ; Level 1
    dc.l IRQ2                 ; Level 2
    dc.l $00C00426            ; Level 3
    dc.l $00C00426,$00C00426,$00C00426,$00C00426  ; Level 4~7
    dc.l $0000056E,$0000056E,$0000056E,$0000056E  ; Traps...
    dc.l $0000056E,$0000056E,$FFFFFFFF,$FFFFFFFF
    dc.l $FFFFFFFF,$FFFFFFFF,$FFFFFFFF,$FFFFFFFF
    dc.l $FFFFFFFF,$FFFFFFFF,$FFFFFFFF,$FFFFFFFF
    dc.l $FFFFFFFF,$FFFFFFFF,$FFFFFFFF,$FFFFFFFF
    dc.l $FFFFFFFF,$FFFFFFFF,$FFFFFFFF,$FFFFFFFF
    dc.l $FFFFFFFF,$FFFFFFFF,$FFFFFFFF,$FFFFFFFF
    dc.l $FFFFFFFF,$FFFFFFFF,$FFFFFFFF,$FFFFFFFF

For CD systems

    org  $0
    dc.l $0010F300,$00C00402,$00C00408,$00C0040E
    dc.l $00C00414,$00C00426,$00C00426,$00C00426
    dc.l $00C0041A,$00C00420,$00C00426,$00C00426
    dc.l $00C00426,$00C00426,$00C00426,$00C0042C
    dc.l $00C00522,$00C00528,$00C0052E,$00C00534
    dc.l $00C0053A,$00C004F2,$00C004EC,$00C004E6
    dc.l $00C004E0,     IRQ2,   VBlank,     IRQ3
    dc.l   Generic,  Generic,  Generic,  Generic
    dc.l   Generic,  Generic,  Generic,  Generic
    dc.l   Generic,  Generic,  Generic,  Generic
    dc.l   Generic,  Generic,  Generic,  Generic
    dc.l   Generic,  Generic,  Generic,  Generic
    dc.l $00C00426,$00C00426,$00C00426,$00C00426
    dc.l $00C00426,$00C00426,$00C00426,$00C00426
    dc.l $00C00426,$00C00426,$00C00426,$00C00426
    dc.l $00C00426,$00C00426,$00C00426,$00C00426