MIPS vs. VAX Showdown: 1991 Data Suggests RISC Dominance Over CISC Giants
A 1991 paper analyzing MIPS (RISC) versus VAX (CISC) claimed that RISC architectures required an average of 2.7 times fewer CPU cycles to perform identical tasks.
Proponents hammered the performance gap, citing MIPS's architectural wins, such as superior register counts and lightning-fast 1-2 cycle conditional branches versus VAX's five cycles. They emphasized that MIPS’s pipeline-filling 'delay slots' provided essential work where VAX supposedly wasted cycles.
The consensus points to RISC's fundamental advantage: achieving higher throughput by trading instruction complexity for sheer speed. However, the underlying data carries a major asterisk, acknowledging that compiler quality and limited test program sets could skew the entire performance narrative.
Key Points
#1RISC outperformed CISC significantly in CPU cycle count.
The analysis cites MIPS needing 2.7 times fewer cycles than VAX for comparable tasks.
#2MIPS featured superior hardware register support.
It possessed 32 general-purpose and 16 floating-point registers, an edge over VAX’s 15 registers, which reduced slow memory calls.
#3Basic operations showed massive speed differentials.
Conditional branches were reported as taking only 1-2 cycles on MIPS, compared to 5 cycles on VAX.
#4Pipeline optimization was key to RISC efficiency.
The discussion noted MIPS utilized 'delay slots' effectively to keep the pipeline full, an advantage seemingly lacking in VAX implementations.
#5The performance gain relies on design philosophy.
The core argument is that RISC achieves speed by using simpler, faster instructions rather than fewer, highly complex ones.
#6Data limitations temper the definitive claim.
The original source admitted the findings could be compromised by the specific compiler quality and the small set of benchmark programs used.
Source Discussions (3)
This report was synthesized from the following Lemmy discussions, ranked by community score.