32-bit pipelined risc processor
DESCRIPTION
32-bit Pipelined RISC Processor. Group 1. aka “Go Us”. CS m152b TA: Young Cho Lab section 1. Alice Wang Ann Ho Jason Fong. IF/ID. ID/EX. EX/MEM. MEM/WB. Register File. PC Control. ALU. Data Memory. Instruction Memory. General Review of a Pipelined Processor. - PowerPoint PPT PresentationTRANSCRIPT
32-bit Pipelined RISC Processor
Group 1Group 1aka “Go Us”aka “Go Us”
Alice WangAnn HoJason Fong
CS m152bTA: Young ChoLab section 1
General Review of a Pipelined Processor
Instruction Memory
Register File ALU
Data Memory
PC Control
IF/ID ID/EX EX/MEM MEM/WB
Memory Controller Design
Design challenge: 32-bit processor with 16-bit memory interface• One every memory access, need to make two memory accesses in
order to get a 32-bit word out of a 16-bit memory interface.
Solution: Clock memory controller twice as fast as rest of processor• Effectively makes a memory access on the rising and falling edge of
the processor’s clock cycle• Each processor clock cycle corresponds to two clock cycles of the
memory controller• This allows two memory accesses per processor clock cycle
Instruction Format
31 28 27 25 24 22 21 19 8 4 3 0
31 28 27 25 24 22 15 0
31 28 15 0
R-type instruction
I-type instruction
J-type instruction
opcode rs rt rd shamt funct
opcode rs rt imm16
opcode imm16
Multiplier
0 • • • 3 2 - b i t v a l u e • • • 0 0 0 0 0 0 0 0 0 0 0
Parallel Multiplier(more efficient, but more hardware)
x4 x3 x2 x1 x0
y0
y1
y2
y3
y4
z9 z8 z7 z6 z5 z4 z3 z2 z1 z0
Data Forwarding
ID/EX EX/MEM MEM/WB
Forward From ALU output
Forward From memory output
Hardware NOP Insertion
1
IF/ID
PC Adder
NOP
Hold PC value
Insert NOP
Data Forwarding and Stall Insertions:Observed Results
Sample program: Bubble-sort 6 numbers
Assembler insertion of NOPs for data hazards and branch/jump delays
Machine code size: 66 words of memory
Execution time: ~750 clock cycles
Hardware data forwarding and stall insertion:
Machine code size: 35 words of memory
Execution time: ~400 clock cycles
Conclusion
Still cooking something up…
We conclude that we do not know what to conclude.
References
• Hennessey and Patterson, Computer Organization and Design (2nd Ed.), 1998, pages 476-495
• Donaldson, John L., “Pipeline Hazards”, http://occs.cs.oberlin.edu/faculty/jdonalds/317/lecture08.html
• Ercegovac, Intro To Digital Systems
• Add stuff about assembler