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Tom Starnes, Analyst
November 2, 2009
MIPS Technology Inc. has been working on a more advanced version of the smallest
instantiation of the MIPS core. The new MIPS M14K is the next step up from the prior
M4K core destined for microcontrollers and area-
Figure 1. MIPS 32-
(all illustrations from MIPS Technology)(click
to enlarge)
In many ways the related press release announces the development of the architecture and then parades a variety of chip, OS, and development tool vendors through the document saying what a great idea it is and that they'll probably support it. We'll have more on this topic in a moment.
What exactly is more advanced about the M14K? Details are still sketchy, but the
big item is a new microMIPS instruction set architecture (ISA). It looks like MIPS
read ARM's Thumb2 handbook and similarly performed a sort on the use of the MIPS
instruction set, really prioritizing instructions and squeezing the most-
The numbers for microMIPS are reported as 35% smaller code space while requiring
maybe 2% more time to execute, which should be a no-
To take advantage of the compressed microMIPS instructions, programs will need to
be recompiled. Is that old, familiar compatibility dance music playing now? Well,
no. Original MIPS32 code will run through the new M14K cores as well as the new 16-
This brings up the one significant difference between the microMIPS engine and ARM's
Thumb2. The microMIPS processor will execute both traditional MIPS32 instructions
and the new compressed 16-
MIPS has also announced a second core -
Figure 2. Block Diagrams showing the memory interface
differences between MIPS
M14K and M14Kc
A few years ago MIPS revealed the very small MIPS M4K core, designed for integration
in microcontrollers and similar products where only low performance is needed and
die size is truly at a premium. The M4K is ideal in such applications that might
otherwise make use of proprietary processor cores, "configurable cores" like ARC
or Tensilica, purpose-
MIPS needed to be sure its instruction set architecture (ISA) is considered for such core opportunities and the M4K opened that door. But no processor architecture can stand still when greater performance, lower power, different configurations, newer process nodes, and extended –and sometimes constrained – operations are evolving in the marketplace. Plus, an IP (intellectual property) company needs extensions to their product line for reasons somewhat different than the reasons chip manufacturers need product extensions.
MIPS Technology is clearly targeting ARM alternatives for the new M14K and M14Kc,
making direct comparisons to the ARM Cortex-
Figure 3. Comparisons by MIPS Technology of
MIPS M14K, M14Kc, ARM Cortex-
The real question of MIPS vs. ARM comes down to just familiarity. Are you an experienced
MIPS developer or a designer familiar with ARM? Is the ecosystem for ARM more favorable
than that for MIPS in your application area? For so many applications these days,
ARM is the good choice, and increasingly so. There are easily five major MCU vendors
which are earnestly backing the ARM Cortex-
Microchip Technology (MCHP) was the first MCU supplier to endorse the MIPS M4K architecture
with a spread of 32-
While this analyst fully expects MCHP to roll out M14K MCUs in the future, Microchip is not ready to say "I do," or even "I would like to," but is saying more "she sure is pretty."
However, the M14K core is not fully formed, and Microchip likes to have the breach
locked and loaded before making chip introductions, so this may not be untoward.
Surely Microchip will offer its customers the advantages offered by the upgraded
MCU core. Whether any other microcontroller vendor will offer off-
It is curious, probably planned, that the announcement of the new MIPS cores comes
barely a week after ARM's annual developer conference, now called ARMtechcon3. There
was no indication at the ARM conference that anyone was concerned about the MIPS
architecture overall, and there has been little ARM-
The way the M14K's fit in MIPS's architecture map can be seen in Figure 1. It's particularly
nice that saying "M14K" rolls off the tongue as easily as M4K and one almost thinks
they might be related. The next hitch in the name game is already essentially occupied
(24K) but we'll let MIPS be creative there later. "MicroMIPS" is a cute name with
various connotations, but the architecture name, MIPS, from day one was an incarnation
of a common industry acronym, so lawyers and engineers will continue to dance around
what is and is not misuse. Is a microMIPS one one-
While MIPS has been a bit distracted the last few years rounding up analog IP and watching their mainstay markets be encroached upon, it has been a while since we've seen processor announcements or new uses of the MIPS architecture. It's good to see them back in the game.
There are many tradeoffs of 8-
Methods varied, with two techniques offered by the major purveyors of PowerPC, an
earlier approach by MIPS in MIPS16, and whole architectures designed to be ARM-
Meantime, where 32-
The MIPS M14K and M14Kc are attractive cores and should keep the low end of the architecture
alive and well. The extent to which this extends MIPS's reach in embedded applications
seems to rest on the shoulders of Microchip Technology. From the other side, Microchip
will get an upgrade to its chosen 32-
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