|Type||Fabless semiconductor company|
|Founder(s)||Daniel W. Dobberpuhl|
|Headquarters||Santa Clara, California, United States|
|Employees||150 person engineering team|
P. A. Semi (originally "Palo Alto Semiconductor") was a fabless semiconductor company founded in Santa Clara, California in 2003 by Daniel W. Dobberpuhl (B.S. EE 1967 University of Illinois, Urbana-Champaign) who was the lead designer for the DEC Alpha 21064 and StrongARM processors. The company employed a 150-person engineering team which included people who had previously worked on processors like Itanium, Opteron and UltraSPARC. Apple Inc acquired P.A. Semi for $278 million in April 2008.
P. A. Semi concentrated on making powerful and power-efficient Power Architecture processors called PWRficient, based on the PA6T processor core. The PA6T was the first Power Architecture core to be designed from scratch outside the AIM alliance (i.e. not by Apple, IBM, or Motorola/Freescale) in ten years. Texas Instruments was one of the investors in P.A. Semi and it was suggested that their fabrication plants would be used to manufacture the PWRficient processors.
PWRficient processors are currently shipping to select customers and were set to be released for worldwide sale in Q4 2007.
There were rumors that P. A. Semi had a relationship with Apple that suggested Apple would be the premier user of the PWRficient processors. That relationship supposedly ended with the Apple–Intel transition when Apple switched from the Power Architecture to Intel's Core processors for their entire line of computers.
Acquisition by Apple 
On 23 April 2008, Apple announced that they had acquired P. A. Semi. While Apple's previous relationship with P. A Semi (see above) would indicate that Apple could use their processors, P. A. Semi manufactures only Power Architecture processors, which Apple does not currently use. At present, Apple only uses ARM and x86 processors.
On 11 June 2008, during the annual Worldwide Developer's Conference, Apple CEO Steve Jobs said that the acquisition was meant to add the talent of P. A. Semi's engineers to Apple's workforce and help them build custom chips for the iPod, iPhone, and other future mobile devices  such as the iPad. P.A. Semi has said that they are willing to supply their PWRficient PA6T-1682M chip on an end-of-life basis, if the Power Architecture license that P.A. Semi holds from IBM can be transferred to the acquiring company.
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- Last version of P.A. Semi homepage from Internet Wayback Machine
- Start-up plans new energy-efficient processor
- PA Semi attacks performance/Watt
- Board level products