When Apple bought P.A. Semi back in 2008 it was the beginning of the era of the iPhone, and their was much speculation as to why Apple was buying a company that made low power high performance PowerPC processors.  Especially since the iPhone ran on ARM and the Mac had moved from PowerPC to x86.

P.A. Semi PA6T-1682M

P.A. Semi was started in 2003 by Daniel Dobberpuhl (who passed away in 2019).  Dobberpuhl was one of the truly greats of microprocessor design, with a career starting at DEC on the T-11 and MicroVAX, before helping DEC transition to the Alpha RISC design (21064).  It was Dobberpuhl who started the design center in Pal Alto (where P.A. Semi would later take its name from) that designed the DEC StrongARM processor.  A processor that was later purchased by Intel and became the XScale line of ARM processors.

After Intel bought the StrongARM line, he then helped start SiByte, making MIPS based RISC CPUs, and continued to do so when SiByte was purchased by Broadcom. So when he started P.A. Semi it was less about PowerPC and more about RISC, PowerPC just happened to be the architecture they chose to use.  The design team had extensive experience on a variety of CPU architectures, including SPARC, Itanium, and the early Opterons.  You can see why this acquisition was so attractive to Apple.

PA6T block diagram

In the few years (2003-2008) from when P.A. was founded to when Apple took them over, they did design, market, and sell a PowerPC processor line called PWRficient based on what they called the PA6T core.  The PA6T-1682M was a Dual core PowerPC processor (the 13xxM was the single core version) with each core running at up to 2GHz with 64K of L1 Instruction cache and 64K of L1 Data cache.  They were fab’d on a 65nm process by TI and ran at 1.1V.  The L2 cache was scalable and shared amongst the cores.  In the 1682M this was a 2M 8-way cache with ECC.  One of the most useful features was their clock stepping.  They could drop to 500MHz at only a few watts per core, and then back up to the full 2GHz in 25us.

AmigaOne X1000 (made by Aeon) PA6T-1682M

The PA6T was only on the marked for a few months (from the end of 2007 to April 2008) before Apple bought them for $300 million, but in this time P.A. Semi had numerous design wins.  Amiga selected it for use in the AmigaOne X1000 computer.  The AmigaOne did not hit market until 2011, which means that while P.A. Semi was bought and completely under control of Apple, they still continued to make, support, and supply their previous customers with the 1682M CPU.  Certainly Amiga wouldn’t be big enough to push Apple to continue making a chip?

They were not, but others were, and the PA6T was such a great processor that it had been selected and designed in to many computer system used by US Defense contractors, and if anyone doesn’t like change, its Defense contractors, so with some prodding by the US Dept of Defense Apple continued to make (or rather have TI make) the PA6T processors.  Curtis-Wright had designed the PA6T into their new CHAMP-AV5 DSP VME64 board, which was used for signals processing across numerous military applications.  They also also used the PA6T (at 1.5GHz) in the VPX3-125 SBC. Themis computers, NEC, Mercury and others designed in the PA6T. Extreme Engineering, another maker of PA6T based boards, referred to the design as ‘ground breaking.’

Extreme Engineering XPedite8070 SBC

It would have been interesting to see what P.A. Semi could have achieved had they not been gobbled up by Apple.  Clearly we see the results of the talent of the P.A. team in what Apple was able to accomplish with their A-series processors, but clearly P.A. had something special for the PowerPC architecture as well.

In car collecting one of the ‘holy grail’ experiences is the ‘Barn Find’  finding and recovering a rare vehicle that has sat untouched, in some barn, or shed for some time.  They are often in rough, but original condition and can evoke much excitement.  As it turns out CPUs are not so different.  I recently purchased a very rough and very old ATARI Arcade board.

The pictures clearly showed it in terrible condition, with lots of oxidation and ‘stuff’ on it.  But it also had a white MOS 6502 processor.  These are some of the very first CPUs made by MOS and are rather desirable, as in addition to their use by ATARI, they were used in the very first Apple computer, the Apple 1.

When the board arrived it was clearly in bad shape, take a look at that nastiness.  What you can’t see, or rather smell, is the cow manure.  Clearly this board was in an actual barn at some point.  Probably relegated to such a retirement after serving in an Arcade parlor or bar for some time, either that or there was some bovin gaming going on.

You can see there is some oxidation on the lids of the various chips as well.  The ROMs and CPU are in sockets.  These sockets are nice, they are not a machine socket but rather a LIF, Low Insertion Force Socket, that helps as the pins on these chips are very delicate, and very possibly corroded.

Before attempting to remove the MCS6502 its best to see what I am working with, so I pulled some of the ROMs nearest to the 6502 to see how their pins looks and how easy they came out of their sockets.  They came out with not a lot of effort but you can see there is some oxidation on the pins.  What we do not want is the pins to be rusted TO the socket and then break off from the forces needed to remove the chip from the socket.

To help mitigate this risk I used some penetrating oil on the pins in the socket.  It seems strange to be squirting oil in the socket but it works.  It will help penetrate the rust and decrease the force needed to remove the 6502. After adding the oil I let the board sit on my heater in my office for several hours.  This helps the oil penetrate, as well as made my office smell like Deep Creep and cow manure, all in a days work.

Then I very gently work on removing the 6502, testing how tight it is and working it out from both ends.  It comes looses with very little drama, hopefully with all its pins intact….

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Original MOS 6501 Processor from 1975 – Designed by Chuck Peddle.

On December 15th one of the truly greats of processor design passed away at age 82.  Chuck Peddle, born in 1937, before semiconductors were even invented, designed the 6502 processor back in 1974.  The 6502 (originally the 6501 actually) went on to become one of the most popular and widely used processors of all time.  It powered the likes of the Apple 1, Commodores, ATARIs and hundred of others.  It was copied, cloned, and expanded by dozens of companies in dozens of countries.  It was so popular that computers were designed to use it in the Soviet Union, eventually making their own version (Pravetz in Bulgaria).

Sitronix ST2064B – Based on the 65C02 – Core is visible in the upper right of the die. (photo by aberco)

The 6502 was a simple but useful 8-bit design, which meant that as time went along and processors migrated to 16 32 and 64-bits and speeds jumped from MHz to GHz the venerable 6502 continued to find uses, and be made, and expanded.  Chuck continued to be involved in all things 6502 until only a few years ago, designing new ways to interface FLASH memory (which hadn’t been invented when he designed the 6502) to the 6502.

The chips themselves, now in CMOS of course, continue to be made to this day by Western Design Center (WDC) and the 65C02 core is used in many many applications, notably LCD monitor controllers and keyboard controllers.  We can hope that the 6502 will have as long of life as Mr. Peddle, though I woud wager, that somewhere, somehow , in 2056 a 6502 will still be running.

Anandtech has an excellent article on the new Apple A8X processor that powers the iPad Air 2.  This is an interesting processor for Apple, but perhaps more interesting is its use, and the reasoning for it.  Like the A5X and A6X before it (there was no A7X) it is an upgrade/enhancement from the A8 it is based on.  In the A5X the CPU was moved from a single core to a dual core and the GPU was increased from a dual core PowerVR SGX543MP2 to a quad-core PowerVR SGX543MP4.  The A6X kept the same dual core CPU design as the A6 but went from a tri-core SGX543MP3 to a quad core SGX554MP4.  Clock speeds were increased in the A5X and A6X over the A5 and A6 respectively.

The A8X continues on this track.  The A8X adds a third CPU core, and doubles the GX6450 GPU cores to 8.  This is interesting as Imagination Technologies (whom the GPUs are licensed from) doesn’t officially support or provide an octa-core GPU.  Apple;s license with Imagination clearly allows customization though.  This is similar to the ARM Architecture license that they have.  They are not restricted to off the shelf ARM, or Imagination cores, they have free reign to design/customize the CPU and GPU cores.  This type of licensing is more expensive, but it allows much greater flexibility.

This brings us to the why.  The A8X is the processor the the newly released iPad Air 2, the previous iPad air ran an A7, which wasn’t a particularly bad processor.  The iPad Air 2 has basically the same spec’s as the previous model, importantly the screen resolution is the same and no significantly processor intense features were added.

When Apple moved from the iPad 2 to the iPad (third gen) they doubled the pixel density, so it made sense for the A5X to have additional CPU and GPU cores to handle the significantly increased amount of processing for that screen. Moving from the A7 to the A8 in the iPad Air 2 would make clear sense from a battery life point of view as well, the new Air has a much smaller batter so battery life must be enhanced, which is something Apple worked very hard on with the A8.  Moving to the A8X, as well as doubling the RAM though doesn’t tell us that Apple was only concerned about battery life (though surely the A8X can turn on/off cores as needed).  Apple clearly felt that the iPad needed a significant performance boost as well, and by all reports the Air 2 is stunningly fast.

It does beg the question though? What else may Apple have in store for such a powerful SoC?

Anandtech and Chipworks deconstructed an Apple A8 processor, the hear of the new iPhone 6.  By their analysis it is not a radical departure from the A7.  It includes a slightly upgrade, but still quad-core, GPU, and an enhanced dual core ARM processor.  The focus here is clearly on battery performance rather then sheer speed.  Perhaps most interesting is the move from Samsung’s 28nm process to TSMC’s 20nm process (Being made by TSMC will hopefully put to rest the rumors of an Apple/Intel tie up once and for all.).  This results in lower power, a smaller die area, and, assuming yields are on par, a lower cost per chip.  Clock speed appears to be close to the same as the A7 at around 1.3GHz, with most performance improvements being architectural. It would appear to be the smallest improvement in the Apple A series, certainly since the A4->A5.

Considering the incremental improvement from the A7, one can only imagine what Apple has in mind for the A9 which is no doubt well under development.

IBM Arthur Processor – 1997

By 1997 the PowerPC 604e was getting a bit dated.  Apple needed an updated faster processor for their new computers and IBM and Motorola needed a new processor to sell to Apple.  The PowerPC 750 was an evolution of the 604e and became the core of Apple’s various G3 systems.

In early 1997 Apple , IBM, and Motorola (together known as the AIM Alliance) were working on what would become the PowerPC 750.  It’s code name? The Arthur.  Apparently someone at IBM or Motorola had a liking for Sherlock Holmes as the 745 was codenamed Conan and the 755 Doyle, after Sir Arthur Conan Doyle, writer of Sherlock Holmes.  This particular part is date coded R20003PAP which means it was made in mid-May of 1997, 6 months before the G3 and PowerPC 750 were officially released.

The card the Arthur processor (hand labeled 300Mhz) resides on is an Apple Prototype known as the Goleta.  The Goleta was one of the first Apple G3 products.   It was to be used in the PowerMac 9700 aka the PowerExpress which was to be a 6 slot G3 PowerMac running at 275MHz.

Apple Goleta G3 Prototype – Click here to see the full card.

It never made it past the prototype stage.  The card is labeled as serial #014 making it a very early prototype, though how many total were made is not known.  The card may have been used at Apple for testing other deigns as well and certainly was a test bench for the new 750 PowerPC Processor.  This was a chaotic time for Apple as they were struggling to pull out of near bankruptcy.  Steve Jobs had only just returned to the company and radically changed what Apple was doing, and what they were not doing (making money).

Apple 1 computers, one of the first personal computers, were introduced in 1976. Now 37 years old they are setting records for auction sales.  In September 2010 one fetched over $20,000 on eBay.  A few months later one with the original box and papers cleared $200,000.  And this week an auction house in Germany sold one for 516,000 Euros (around $670,000 depending on the exchange rate).  Apparently a refurbished and now working model. this is one of the highest prices ever for a vintage computer.

Who knows, in 30 years the original iPhone 2G may set records for sales, but considering the number built, who knows how many will be around in 2040, or how many will have the original box.

The introduction of the iPhone 5 was also the introduction of Apple’s first truly original Application Processor design.  The iPhone 2, 3G and 3GS all featured designs by Samsung.  The iPhone 4 introduced the A4, which was closely based on the Hummingbird Cortex-A8 core developed with Samsung and Intrinsity, again, not a truly Apple design.  The iPhone 4S introduced the A5 (and the A5X used in the iPad 2).  The A5 is based on the ARM Cortex-A9 MPCore, a standard ARM design, albeit with many added features, but architecturally, the processor is not original, just customized.

ARM provides cores designs for use by developers, such as the Cortex-A9, A8, etc.  These are complete designs of processors that you can drop into your system design as a block, add your own functions, such as a graphics system, audio processing, image handling, radio control, etc and you have your processor.  This is the way many processor vendors go about things.  They do not have to spend the time and effort to design a processor core, just pick one that meets their needs (power budget, speed, die area) and add any peripherals   Many of these peripherals are also licensed as Intellectual Property (IP) blocks making building a processor in some ways similar to construction with Legos.  This is not to say that this is easy, or the wrong way to go about things, it is in fact the only way to get a design to market in a matter of weeks, rather then years.  It allows for a wide product portfolio that can meet many customers needs.  The blocks are often offered for a specific process, so not only can you purchase a license to a Cortex-A9 MPCore, you can purchase one that is hardware ready for a TSMC 32nm High-k Metal Gate process, or a 28nm Global Foundries process.  This greatly reduces the amount of work needed to make a design work with a chosen process. This is what ARM calls the Processor Foundry Program.

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Back in 2010 we did a write up on the many processors in each iPhone for each version through the iPhone 4.  Since then Apple has released the iPhone 4 (CDMA) and the mid-cycle refresh iPhone 4S.  Seeing as the iPhone 5 should be released on September 12th here is a quick update to bring our table up to date.

CPUs by function and generation of iPhone:

Apple iPhone 4 CDMA

The CDMA version of the iPhone 4 switched from an Infineon X-Gold baseband to a Qualcomm MDM6600 running a 512MHz ARM1136JS core.  Interestingly this baseband supports GSM but due to antenna issues it is not implemented here. The Qualcomm Gobi, as it is known, also has integrated GPS, removing the need for the old Broadcom BCM4750.  This sets the stage for the iPhone 4S.

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A Brief History

Long before the mess of Apple vs. Samsung (and seemingly everyone else), there was another famous company, with a patent in hand, that it seemed everyone was violating.  The issue of Intellectual Property (IP), and its associated patents has long been an issue in the technology business, and certainly in the business of CPU’s.  There are many many functions inside a CPU, different structures for handling instructions, memory access, cache algorithms, branch prediction etc.  All of these are unique, intellectual property.  It doesn’t matter if you implement them with a slightly different transistor structure, as long as the end product is relatively the same, there is the risk of violating a patent.  Patents are tricky things, and litigating them can be very risky.  You must balance the desire to keep competition from violating your IP, but at the same time minimize the risk that your patent is declared invalid.  This is why most cases end up in an out of court settlement, usually via arbitration.  Actual patent jury trials are fairly rare, as they are very expensive and very risky to all parties involved

Infringing?

In the early days (1970’s and early 1980’s) there was routine and widespread cross licensing in the industry.  Many companies didn’t have the fab capacity to reliably meet demand (IBM wouldn’t purchase a device unless it was made by at least 2 companies for this very reason) so they would contract with other manufacturers to make their design.  Having other companies manufacture your design, or compatible parts, also increased the market share of your architecture (8086, 68k etc).  For years AMD made and licensed most everything Intel made, AMD also licensed various peripheral chips to Intel (notably the 9511/2 FPU).  As the market grew larger, the competition increased, Intel (and others) began to have enough reliable fab capacity to safely single source devices.  Meanwhile other companies continued to make compatible products, based on previous licensing.  AMD notably made x86 CPU’s that ate into Intel’s market share. In the 1970’s Intel had cross license agreements with AMD, IBM, National, Texas Instruments, Mostek, Siemens, NEC and many others.

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