1. Control sequence to add two registers
We want to add register R2 and R5 and write result back in R3
Set RA1=010, RA2=101, WA=011, WR=1, OpCode=100, SC=00, LDM=0, EMR=0, EALU=1, EI=0, WOUT=0, WM=0, RM=0, EM=0, WAD=0
Mem
Unit WM EM
Addr RM
WAD A L U
OpCode
Reg
File WA WR
RA2
RA1
Input EI
Output
WOUT
EALU M-
EMR
LDM S H I F T SC

2. Control sequence to read memory into R3
We want to read a memory location into R3
Which memory location? Say address is in R2
Two steps, transfer R2 in Addr register in one cycle
Then read memory into R3 in the next cycle
Why can’t we do in one cycle?
Mem
Unit WM EM
Addr RM
WAD A L U
OpCode
Reg
File WA WR
RA2
RA1
Input EI
Output
WOUT
EALU M-
EMR
LDM S H I F T SC

3. Control sequence to write memory into R3
Next we want to write contents of R3 in memory location whose address is in R2
Again we need two steps
Transfer R2 in Addr register in one cycle
Then write contents of R3 in the next cycle
Write control signals for two steps
Mem
Unit WM EM
Addr RM
WAD A L U
OpCode
Reg
File WA WR
RA2
RA1
Input EI
Output
WOUT
EALU M-
EMR
LDM S H I F T SC