AT91SAM9261中内部ROM有32K，可惜启动代码只用了不到8K的空间，目前看来还是有浪费之嫌的（想想当年51就寒碜）
上电启动代码的反汇编，只走了第一个S文件：
ROM:00400000 AREA ROM, CODE, READWRITE, ALIGN=0
ROM:00400000 ; ORG 0x400000
ROM:00400000 CODE32
ROM:00400000 B loc_400020 //Reset
ROM:00400000 ; --------------------------------------------------------------------------------
ROM:00400004 DCB 0xFE ; //Other Exception vectors
ROM:00400005 DCB 0xFF
ROM:00400006 DCB 0xFF
ROM:00400007 DCB 0xEA ;
ROM:00400008 DCB 0x2F ;
ROM:00400009 DCB 0
ROM:0040000A DCB 0
ROM:0040000B DCB 0xEA ;
ROM:0040000C DCB 0xFE ;
ROM:0040000D DCB 0xFF
ROM:0040000E DCB 0xFF
ROM:0040000F DCB 0xEA ;
ROM:00400010 DCB 0xFE ;
ROM:00400011 DCB 0xFF
ROM:00400012 DCB 0xFF
ROM:00400013 DCB 0xEA ;
ROM:00400014 DCB 0xFE ;
ROM:00400015 DCB 0xFF
ROM:00400016 DCB 0xFF
ROM:00400017 DCB 0xEA ;
ROM:00400018 DCB 0xFE ;
ROM:00400019 DCB 0xFF
ROM:0040001A DCB 0xFF
ROM:0040001B DCB 0xEA ;
ROM:0040001C DCB 0xFE ;
ROM:0040001D DCB 0xFF
ROM:0040001E DCB 0xFF
ROM:0040001F DCB 0xEA ;
ROM:00400020 ; --------------------------------------------------------------------------------
ROM:00400020
ROM:00400020 loc_400020
ROM:00400020 MOV SP, #0x328000 //stack setup
ROM:00400024 LDR R1, =0xFFFFFC00 //即LDR R1, =AT91C_PMC_SCER ；(PMC) System Clock Enable Register
ROM:00400028 LDR R0, =0x4001
ROM:0040002C STR R0, [R1,#0x20] //即STR R0, [R1,#MOR] ；(PMC) Main Oscillator Register
ROM:00400030 MOV R4, #1
ROM:00400034
ROM:00400034 loc_400034
ROM:00400034 LDR R3, [R1,#0x68] //即LDR R3, [R1,#SR] ；(PMC) Status Register
ROM:00400038 AND R3, R4, R3
ROM:0040003C CMP R3, #1
ROM:00400040 BNE loc_400034 //等待主时钟振荡器稳定
ROM:00400044 MOV R0, #1
ROM:00400048 STR R0, [R1,#0x30] //即STR R0, [R1,#MCKR] ；(PMC) Master Clock Register
ROM:0040004C MOV R4, #8
ROM:00400050
ROM:00400050 loc_400050
ROM:00400050 LDR R3, [R1,#0x68] //读取PMC状态
ROM:00400054 AND R3, R4, R3
ROM:00400058 CMP R3, #8
ROM:0040005C BNE loc_400050
ROM:00400060 ADR R2, off_400094 //等待芯片时钟稳定
ROM:00400064 LDMIA R2, {R0,R1,R3,R4}
ROM:00400068 CMP R0, R1
ROM:0040006C BEQ loc_400080
ROM:00400070
ROM:00400070 loc_400070
ROM:00400070 CMP R1, R3 //copy RW section to IRAM
ROM:00400074 LDRCC R2, [R0],#4
ROM:00400078 STRCC R2, [R1],#4
ROM:0040007C BCC loc_400070
ROM:00400080
ROM:00400080 loc_400080
ROM:00400080 MOV R2, #0
ROM:00400084
ROM:00400084 loc_400084
ROM:00400084 CMP R3, R4 //copy ZI section to IRAM and Zero init
ROM:00400088 STRCC R2, [R3],#4
ROM:0040008C BCC loc_400084
ROM:00400090 B loc_4000A4
ROM:00400090 ; --------------------------------------------------------------------------------
ROM:00400094 off_400094 DCD 0x401E9C //|Image$$RO$$Limit|
ROM:00400098 DCB 0 //|Image$$RW$$Base|
ROM:00400099 DCB 0x70 ; p
ROM:0040009A DCB 0x32 ; 2
ROM:0040009B DCB 0
ROM:0040009C DCB 0x10 //|Image$$ZI$$Base|
ROM:0040009D DCB 0x70 ; p
ROM:0040009E DCB 0x32 ; 2
ROM:0040009F DCB 0
ROM:004000A0 DCB 0x88 ; ? //|Image$$ZI$$Limit|
ROM:004000A1 DCB 0x70 ; p
ROM:004000A2 DCB 0x32 ; 2
ROM:004000A3 DCB 0
ROM:004000A4 ; --------------------------------------------------------------------------------
ROM:004000A4
ROM:004000A4 loc_4000A4
ROM:004000A4 LDR R0, =sub_401690
ROM:004000A8 MOV LR, PC
ROM:004000AC BX R0
ROM:004000B0 LDR R0, =sub_40066C
ROM:004000B4 MOV LR, PC
ROM:004000B8 BX R0
ROM:004000BC MRC p15, 0, R5,c1,c0
ROM:004000C0 MOV R6, #0x1000
ROM:004000C4 ORR R5, R5, R6
ROM:004000C8 MCR p15, 0, R5,c1,c0
ROM:004000CC
ROM:004000CC loc_4000CC
ROM:004000CC LDR R0, =sub_401338
ROM:004000D0 MOV LR, PC
ROM:004000D4 BX R0 //Jump to main Function
ROM:004000D8
ROM:004000D8 loc_4000D8
ROM:004000D8 B loc_4000D8 //Normally, never occur.