Lecture Notes for Computer Architecture II - St. Cloud State University

Lecture 23 Processor Design - Data path for Lw/Sw instructions
Example
Implement SW/LW
2 units needed for sw/1w
- Data memory
- Sign extension unit
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Data Memory
Write
data
Address
Data Memory
Memory write
Memory read
Read data
SW
Store word - write data in the data memory
Memory write signal = 1 when writing data provided by the write data in the
address provided by the address
No outputs
Lw
Load word - reads data from memory
Memory read is = 1 when reading data from the address
Output - read data
Sign extension unit
16 bit
sign
extension
unit
32 bit
Data path for 1w/sw
- need register access
- calculate memory address
- read from memory
- write into register file for lw instruction
- write into data memory for sw instruction