正常情况下MDK是不能同时支持51和AMM的，除非装两个，但是这样太麻烦了，这个修改方法很简单，已经用了很久了，不知道的可以试试。

首先先装ARM版，破解一下，然后把安装目录下的TOOLS.INI

文件里面添加红字内容（最好备份下），注意路径

[UV2]

CDB0=UV4\STC.CDB("STC")

ORGANIZATION="Microsoft"

NAME="Microsoft", "1"

EMAIL="1"

ARMSEL=1

USERTE=1

BOOK0="UV4\RELEASE_NOTES.HTM" ("uVision Release Notes",GEN)

RTEPATH="D:\KEIL05\PACK"

DEVICE_BOOKS=

SocketPort=1969854680

[ARM]

PATH="D:\KEIL05\ARM\"

VERSION=5.00

PATH1="C:\Program Files\GNU Tools ARM Embedded\4.7 2012q4\"

TOOLPREFIX=arm-none-eabi-

CPUDLL0=SARM.DLL(TDRV0,TDRV5,TDRV6,TDRV9)

# Drivers for ARM7/9 devices

CPUDLL1=SARMCM3.DLL(TDRV1,TDRV2,TDRV3,TDRV4,TDRV5,TDRV7,TDRV8,TDRV10,TDRV11,TDRV12,TDRV13,TDRV14,TDRV15)

# Drivers for Cortex-M devices

CPUDLL2=SARMCR4.DLL(TDRV7)

#

Drivers for Cortex-R4 devices

BOOK0="HLP\RELEASE_NOTES.HTM" ("Release Notes",GEN)

BOOK1="HLP\ARMTOOLS.chm" ("Complete User's Guide

Selection",C)

TDRV0=BIN\UL2ARM.DLL("ULINK2/ME ARM Debugger")

TDRV1=BIN\UL2CM3.DLL("ULINK2/ME Cortex Debugger")

TDRV2=BIN\AGDIRDI.DLL("RDI Interface Driver")

TDRV3=BIN\ABLSTCM.dll("Altera Blaster Cortex Debugger")

TDRV4=BIN\lmidk-agdi.dll("Stellaris ICDI")

TDRV5=Signum\SigUV3Arm.dll("Signum Systems JTAGjet")

TDRV6=Segger\JLTAgdi.dll("J-LINK / J-TRACE ARM")

TDRV7=Segger\JL2CM3.dll("J-LINK / J-TRACE Cortex")

TDRV8=BIN\ULP2CM3.DLL("ULINK Pro Cortex Debugger")

TDRV9=BIN\ULP2ARM.DLL("ULINK Pro ARM Debugger")

TDRV10=NULink\Nu_Link.dll("NULink Debugger")

TDRV11=SiLabs\SLAB_CM_Keil.dll("SiLabs UDA Debugger")

TDRV12=STLink\ST-LINKIII-KEIL_SWO.dll ("ST-Link Debugger")

TDRV13=BIN\CMSIS_AGDI.dll("CMSIS-DAP Debugger")

TDRV14=BIN\DbgFM.DLL("Fast Models Debugger")

TDRV15=PEMicro\Pemicro_ArmCortexInterface.dll("PEMicro Debugger")

LIC0=TIV74-FXUYI-GI05Q-NP6N4-0EQBH-JEH8Y

[ARMADS]

PATH="D:\KEIL05\ARM\"

PATH1=".\ARMCC\bin\"

CPUDLL0=SARM.DLL(TDRV0,TDRV5,TDRV6,TDRV9)

# Drivers for ARM7/9 devices

CPUDLL1=SARMCM3.DLL(TDRV1,TDRV2,TDRV3,TDRV4,TDRV5,TDRV7,TDRV8,TDRV10,TDRV11,TDRV12,TDRV13,TDRV14,TDRV15)

# Drivers for Cortex-M devices

CPUDLL2=SARMCR4.DLL(TDRV7)

#

Drivers for Cortex-R4 devices

BOOK0="HLP\RELEASE_NOTES.HTM" ("Release Notes",GEN)

BOOK1="HLP\ARMTOOLS.chm" ("Complete User's Guide Selection",C)

TDRV0=BIN\UL2ARM.DLL("ULINK2/ME ARM Debugger")

TDRV1=BIN\UL2CM3.DLL("ULINK2/ME Cortex Debugger")

TDRV2=BIN\AGDIRDI.DLL("RDI Interface Driver")

TDRV3=BIN\ABLSTCM.dll("Altera Blaster Cortex Debugger")

TDRV4=BIN\lmidk-agdi.dll("Stellaris ICDI")

TDRV5=Signum\SigUV3Arm.dll("Signum Systems JTAGjet")

TDRV6=Segger\JLTAgdi.dll("J-LINK / J-TRACE ARM")

TDRV7=Segger\JL2CM3.dll("J-LINK / J-Trace Cortex")

TDRV8=BIN\ULP2CM3.DLL("ULINK Pro Cortex Debugger")

TDRV9=BIN\ULP2ARM.DLL("ULINK Pro ARM Debugger")

TDRV10=NULink\Nu_Link.dll("NULink Debugger")

TDRV11=SiLabs\SLAB_CM_Keil.dll("SiLabs UDA Debugger")

TDRV12=STLink\ST-LINKIII-KEIL_SWO.dll ("ST-Link Debugger")

TDRV13=BIN\CMSIS_AGDI.dll("CMSIS-DAP Debugger")

TDRV14=BIN\DbgFM.DLL("Fast Models Debugger")

TDRV15=PEMicro\Pemicro_ArmCortexInterface.dll("PEMicro Debugger")

RTOS0=Dummy.DLL("Dummy")

RTOS1=VARTXARM.DLL ("RTX Kernel")

[C51]

PATH="D:\KEIL05\C51\"\" \"

SN=K1DZP-5IUSH-A01UE

VERSION=V9.01

BOOK0="HLP\RELEASE_NOTES.HTM"

("Release Notes",GEN)

BOOK1="HLP\GS51.PDF" ("uVision2

Getting Started",GEN)

BOOK2="HLP\C51.PDF" ("C51 User's

Guide",GEN)

BOOK3="HLP\C51LIB.CHM" ("C51 Library

Functions",C)

BOOK4="HLP\A51.PDF"

("Assembler/Utilities",GEN)

BOOK5="HLP\TR51.CHM" ("RTX51 Tiny

User's Guide",GEN)

BOOK6="HLP\DBG51.CHM" ("uVision2

Debug Commands",GEN)

BOOK7="HLP\ISD51.CHM" ("ISD51 In

System Debugger",GEN)

BOOK8="HLP\FlashMon51.CHM" ("Flash

Monitor",GEN)

BOOK9="MON390\MON390.HTM" ("MON390:

Dallas Contiguous Mode Monitor",GEN)

TDRV0=BIN\MON51.DLL ("Keil Monitor-51

Driver")

TDRV1=BIN\ISD51.DLL ("Keil ISD51 In-System

Debugger")

TDRV2=BIN\MON390.DLL ("MON390: Dallas

Contiguous Mode")

TDRV3=BIN\LPC2EMP.DLL ("LPC900 EPM

Emulator/Programmer")

TDRV4=BIN\UL2UPSD.DLL ("ST-uPSD ULINK

Driver")

RTOS1=RTXTINY.DLL ("RTX-51 Tiny")

RTOS2=RTX51.DLL ("RTX-51 Full")

LIC0=76PCX-HP74U-IRIXW-QEPXN-32TWY-CALVY

[C251]

BOOK0="HLP\RELEASE_NOTES.HTM"

("Release Notes",GEN)

BOOK1="HLP\GS51.PDF" ("uVision2

Getting Started",GEN)

BOOK2="HLP\C251.PDF" ("C251 User's

Guide",GEN)

BOOK3="HLP\C251LIB.CHM" ("C251

Library Functions",C)

BOOK4="HLP\A51.PDF"

("Assembler/Utilities",GEN)

BOOK5="HLP\DBG251.CHM" ("uVision2

Debug Commands",GEN)

TDRV0=BIN\MON251.DLL ("Keil Monitor-251

Driver")

VERSION=V3.5

修改后保存，然后把keil51的安装文件夹下的C51文件夹复制到ARM版的安装目录下，然后选择器件里就有51系列单片机了

之后再去STC官网下个STC.CDB文件复制到安装目录下的UV4文件夹，就变成这样了