TDT4160 Datamaskiner grunnkurs

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TDT4160 Datamaskiner grunnkurs

• Uke 3, time 2
• Haakon Dybdahl

2
I dag

• Mikroarkitektur Kap 7
• Utføring av en instruksjon
• Fastkablet (eng hardwired)
• Mikrokode

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Internal processor
bus
Control signals
PC
Instruction
Address
decoder and
lines
MAR
control logic
Memory
bus
MDR
Data
IR
lines
Y
R0
Constant 4
Select
MUX
Add
A
B
Sub
R
n
1
-
(
)
ALU
control
ALU
lines
Carry-in
XOR
TEMP
Z
Figure 7.1. Single-bus organization of the
datapath inside a processor.
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Figure 7.3. Input and output gating for one
register bit.
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Figure 7.4. Connection and control signals for
register MDR.
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Step
Action
1
PC
,
RB,
MAR
,
Read,
IncPC
out
in
2
WMF
C
3
MDR
,
RB,
IR
in
outB
4
R4
,
R5
,
SelectA,
Add,
R6
,
End
outA
outB
in
Figure 7.9. Control sequence for the instruction.
Add R4,R5,R6, for the three-bus organization in
Figure 7.8.
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Step
Action
1
PC
,
MAR
,
Read,
Select4,
Add,
Z
out
in
in
2
Z
,
PC
,
Y
,
WMF
C
out
in
in
3
MDR
,
IR
out
in
4
R3
,
MAR
,
Read
out
in
5
R1
,
Y
,
WMF
C
out
in
6
MDR
,
SelectY,
Add,
Z
out
in
7
Z
,
R1
,
End
out
in
instruction
Add
(R3),R1.
Zin T1 T6 ADD T4 BR ....
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Branch
Add
T
T
4
6
T
1
Figure 7.12. Generation of the Zin control signal
for the processor in Figure 7.1.
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External
inputs
Starting and
Condition
branch address
IR
codes
generator
Clock
m
P
C
Control
CW
store
Figure 7.18. Organization of the control unit to
allow conditional branching in the
microprogram.
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Mode
OP code
0
1
0
Rsrc
Rdst
Contents of IR
0
3
4
7
8
10
11
Address
Microinstruction
(octal)
000
PC
, MAR
, Read, Select
, Add, Z
4
in
out
in
001
Z
, PC
, Y
, WMFC
out
in
in
002
MDR
, IR
out
in
003
Branch
PC
101 (from Instruction decoder)
m
m

PC
IR

PC
IR


IR


IR

m

m

10
9
8
5,4
10,9
3
121
Rsrc
, MAR
, Read, Select4, Add, Z
in
out
in
122
Z
, Rsrc
out
in


123
m
Branch
m
PC
170
m
PC
IR
, WMFC
0
8
170
MDR
, MAR
, Read, WMFC
out
in
171
MDR
, Y
out
in
172
Rdst
, SelectY
, Add, Z
in
out
173
Z
, Rdst
, End
out
in
Figure 7.21.
Microinstruction for Add (Rsrc),Rdst.
Note
Microinstruction at location 170 is not executed
for this addressing mode.
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