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mipspipelinecpu-architecture
Jiew Meng
Jiew Meng

Reputation: 88317

What does PCWrite & IFWrite in MIPS Pipeline do/refer to?

From the Patterson/Hennessy book:

Whats PCWrite & IF/DWrite (2 left most control signals from hazard detection unit)

Upvotes: 0

Views: 3528

Answers (2)

Ilya
Ilya

Reputation: 5613

  • When PCWrite is deasserted (=0), the IF stage does not advance the PC register. This causes it to read the same instruction over and over again. This effectively freezes the instruction that's currently in the IF stage.

  • When IF/DWrite is deasserted (=0), the IF/ID register is not written to, making it deliver the same instruction to the IF stage over and over again. This effectively freezes the instruction that's currently in the ID stage.

See page 373 in Computer Organization and Design (4th Edition).

Upvotes: 1

Jiew Meng
Jiew Meng

Reputation: 88317

Ok, I figured PCWrite, IF/DWrite is used for stalling, set to 0 to stall

Upvotes: 0

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