Broadcomm's reason of using MIPS is more likely a decision to maintain HW and SW re-use to the max considering one of their biggest customers is Motorola Broadband that back in the early 2000-2002 moved away from Motorola Semi 68k 32 bit cores to MIPS, ever since Broadcomm's SoC designs for the Cable boxes, modems, etc have been using MIPS driven by Motorola Broadband (formerly GI) designs.
Back in 2000-2002 ARM was making his first efforts with the ARM7 in embedded space targeting low power consumption designs, cable boxes being plugged to the wall wasn't their focuss.
At the moment ARM as grown exponentially vs MIPS because the mobile market has done the same, but we still don't see a lot or ARM away from the mobile space.
Maybe the real reason to develop your own CPU is to make it more difficult for the competition to create cheap knock-offs. To me it seem like too much of an internal cost to do this for any other reason...
This processor is the first MIPS core that challenges the ARM and Atom for performance. I think Broadcom had to do this to keep pace. The investment Broadcom has in the MIPS processor must be huge for them to invest in improving the MIPS core vs. switching to ARM.
I personally like the competition in the embedded processor marketplace. This can only benefit the consumer with more full featured products.
per core license costs are much better with MIPS. if large address space is important, MIPS had 64bit implementation in the early 90s / licenses for 64 bit for 10 years or so. there are also a ton of hw extensions for MIPS (like ARM).
Broadcom has been an old partner of MIPS so they still continue to churn out SOCs based on MIPS but with the effort they put into the power management and performance improvement I feel they could have gotten much bigger gains with ARM Cortex-A9s.
Here is a summary of some MIPS advantages according to MIPS CEO:
"MIPS has 32-bit and 64-bit processors. ARM does not have 64-bit. MIPS has single and multithreaded designs. ARM does not have multithreaded," he points out.
The only benefit of MIPS over ARM I can think of is that a lot of embedded software for things like set-top- boxes, modems and routers run on MIPS. Their licensing structure may also cost less than ARM.
Other than that, there really isn't that many technical advantages to either ISA.
IMO, PowerPC is superior to both from a design standpoint.
Broadcom has been using MIPS for processor of appliances. The industry seems to go for ARM and ARM is really taking the lead in various areas. What's the benefit of using MIPS over ARM? Is there any cost concern?
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