VHDL8位CPU设计包含程序Word格式.docx
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ACC-[X]→ACC
JMPGZX
05H
IFACC>
0THENX→PCELSEPC+1→PC
ANDX
06H
ACCand[X]→ACC
ORX
07H
ACCor[X]→ACC
NOTX
08H
Not[X]→ACC
SHIFTRX
09H
SHIFLACCtoRIGHT1bit,LogicShift
SHIFTLX
0AH
SHIFTACCtoLEFT1bit,LogicShift
MPYX
0BH
ACC×
HALT
0CH
HALTAPROGRAM
Aprogramisdesignedtotesttheseinstructions:
Calculatethesumofallintegersfrom1to100.
（1）,programmingwithClanguage:
sum=0;
temp=100;
loop:
sum=sum+temp;
temp=temp-1;
iftemp>
=0gotoloop;
end
（2）,AssumeintheRAM_DQ:
sumisstoredatlocationA4,
tempisstoredatlocationA3,
thecontentsoflocationA0is0,
thecontentsoflocationA1is1,
thecontentsoflocationA2is10010=6416.
WecantranslatetheaboveClanguageprogramwiththeinstructionslistedinTable1intotheinstructionprogramasshowninTable2.
Table2Exampleofaprogramtosumfrom1to100
ProgramwithC
Programwith
instructions
ContentsofRAM_DQinHEX
Address
Contents
LOADA0
00
02A0
STOREA4
01
01A4
temp=100
LOADA2
02
02A2
STOREA3
03
01A3
loop:
LOOP:
LOADA4
04
02A4
ADDA3
05
03A3
06
LOADA3
07
02A3
SUBA1
08
04A1
09
0gotoloop;
JMPGZLOOP
0A
0504
end;
0B
0C00
0C
…
A0
0000
A1
0001
A2
0064
A3
A4
III.InternalRegistersandMemory
MAR（MemoryAddressRegister）
MARcontainsthememorylocationofthewordtobereadfromthememoryorwrittenintothememory.Here,READoperationisdenotedastheCPUreadsfrommemory,andWRITEoperationisdenotedastheCPUwritestomemory.Inourdesign,MARhas8bitstoaccessoneof256addressesofthememory.
MBR（MemoryBufferRegister）
MBRcontainsthevaluetobestoredinmemoryorthelastvaluereadfrommemory.MBRisconnectedtotheaddresslinesofthesystembus.Inourdesign,MBRhas16Bits.
PC（ProgramCounter）
PCkeepstrackoftheinstructionstobeusedintheprogram.Inourdesign,PChas8bits.
IR（InstructionRegister）
IRcontainstheopcodepartofaninstruction.Inourdesign,IRhas8bits.
BR（BufferRegister）
BRisusedasaninputofALU,itholdsotheroperandforALU.Inourdesign,BRhas
16bits.
LPM_RAM_DQ
LPM_RAM_DQisaRAMwithseparateinputandoutputports.Itworksasamemory,anditssizeis256×
16.Althoughit’snotaninternalregisterofCPU,weneedittosimulateandtesttheperformanceofCPU.
LPM_ROM
LPM_ROMisaROMwithoneaddressinputportandonedataoutputport,anditssizeofdatais32bitswhichcontainscontrolsignalstoexecutemicro-operations.
IV.ALU
ALU（ArithmeticLogicUnit）isacalculationunitwhichaccomplishesbasicarithmeticandlogicoperations.Inourdesign,someoperationsmustbesupportedwhicharelistedasfollows:
Table3ALUOperations
ALUcontrolsignal
Operations
Explanations
3H
ADD
ACC←ACC+BR
4H
SUB
ACC←ACC-BR
6H
AND
ACC←ACCandBR
7H
OR
ACC←ACCorBR
8H
NOT
ACC←notACC
9H
SHIFTR
ACC←ShiftACCtoRight1bit
SHIFTL
ACC←ShiftACCtoLeft1bit
V.Micro-programmedControlUnit
IntheMicroprogrammedcontrol,themicroprogramconsistsofsomemicroinstructionandthemicroprogramisstoredincontrolmemorythatgeneratesallthecontrolsignalsrequiredtoexecutetheinstructionsetcorrectly.Themicroinstructioncontainssomemicro-operationswhichareexecutedatthesametime.
Figure2showsthekeyelementsofsuchanimplementation.
Thesetofmicroinstructionsisstoredinthecontrolmemory.Thecontroladdressregistercontainstheaddressofthenextmicroinstructionstoberead.Whenamicroinstructionisreadfromthecontrolmemory,itistransferredtoacontrolbufferregister.Theregisterconnectstothecontrollinesemanatingfromthecontrolunit.Thus,readingamicroinstructionfromthecontrolmemoryisthesameasexecutingthatmicroinstruction.Thethirdelementshowninthefigureisasequencingunitthatloadsthecontroladdressregisterandissuesareadcommand.
Figure2ControlUnitMicro-architecture
（I）Totalcontrolsignalsforinstructionsarelistedasfollows:
Table4Controlsignalsforthemicro-operations
BitsinControlMemory
Micro-operation
Meaning
C0~C7
/
BranchAddresses
C8
PC←0
ClearPC
C9
PC←PC+1
IncrementPC
C10
PC←MBR[7..0]
MBR[7..0]toPC
C11
ACC←0
ClearACC
C12--C15
ALUCONTROL
ControloperationsofALU
C16
R
ReaddatafromMemorytoMBR
C17
W
WritedatatoMemory
C18
MAR←MBR[7..0]
MBR[7..0]toMARasaddress
C19
MAR←PC
PCvaluetoMAR
C20
MBR←ACC
ACCvaluetoMBR
C21
IR←MBR[15..8]
MBR[15..8]toIRasopcode
C22
BR←MBR
CopyMBRtoBR
C23
CAR←CAR+1
IncrementCAR
C24
CAR←C0~C7
C7~C0toCAR
C25
CAR←OPCODE+CAR
AddOPtoCAR
C26
CAR←0
ResetCAR
C27--C31
Notuse
-----------
（II）Thecontentsinrom.mifandthecorrespondingmicroprogramsarelistedasfollows:
0:
00810000;
R←1,CAR←CAR+1
1:
00A00000;
OP←MBR[15..8],CAR←CAR+1
2:
02000000;
CAR←CAR+OP
3:
01000014;
CAR←14H
4:
01000019;
CAR←19H
5:
0100001E;
CAR←1EH
6:
01000023;
CAR←23H
7:
01000041;
CAR←41H
8:
01000028;
CAR←28H
9:
0100002D;
CAR←2DH
a:
01000032;
CAR←32H
b:
01000037;
CAR←37H
c:
0100003C;
CAR←3CH
d:
01000046;
CAR←46H
e:
0100004B;
CAR←4H
f:
00000000;
………
14:
00840000;
MAR←MBR[7..0],CAR←CAR+1------STORE
15:
00920200;
MBR←ACC,PC←PC+1,W←1,CAR←CAR+1
16:
04080000;
CAR←0
17:
18:
19:
MAR←MBR[7..0],CAR←CAR+1------LOAD
1a:
00810A00;
PC←PC+1,R←1,ACC←0,CAR←CAR+1
1b:
00C03000;
BR←MBR,ACC←ACC+BR,CAR←CAR+1
1c:
1d:
1e:
MAR←MBR[7..0],CAR←CAR+1----------ADD
1f:
00810200;
PC←PC+1,R←1,CAR←CAR+1
20:
21:
22:
23:
MAR←MBR[7..0],CAR←CAR+1----------SUB
24:
25:
00C04000;
BR←MBR,ACC←ACC-BR,CAR←CAR+1
26:
27:
28:
MAR←MBR[7..0],CAR←CAR+1---------AND
29:
2a:
00C06000;
BR←MBR,ACC←ACCANDBR,CAR←CAR+1
2b:
2c:
2d:
MAR←MBR[7..0],CAR←CAR+1---------OR
2e:
2f:
00C07000;
BR←MBR,ACC←ACCORBR,CAR←CAR+1
30:
31:
32:
MAR←MBR[7..0],CAR←CAR+1----------NOT
33:
00808200;
PC←PC+1,ACC←NOTACC,CAR←CAR+1
34:
35:
36:
37:
MAR←MBR[7..0],CAR←CAR+1----------SHIFTR
38:
08092000;
PC←PC+1,ACC←SHIFTACCtoRight1bit,CAR←CAR+1
39:
3a:
3b:
3c:
MAR←MBR[7..0],CAR←CAR+1-----------SHIFTL
3d:
0080A200;
PC←PC+1,ACC←SHIFTACCtoLeft1bit,CAR←CAR+1
3e:
3f:
40:
41:
MAR←MBR[7..0],CAR←CAR+1-----------JMPGEZ
42:
00805000;
CAR←CAR+1,
43:
44:
45:
46:
MAR←MBR[7..0],CAR←CAR+1------------MPY
47:
48:
00C0B000;
BR←MBR,ACC←ACC*BR,CAR←CAR+1
49:
4a:
4b:
CAR←4BH------------------------------HALT
4c:
（III）Thesimulationwaveformsofsomeoperates
1,load,add,store,halt（22+10）
ThecontentsinRAM:
0:
022A;
Load2A
032B;
ADD2B
012C;
Store2C
0C00;
Halt
2a:
0016;
2b:
0
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