TANDEM CLX 800 Processor – VLSI CMOS 1u process – 16MHz.

Tandem Computers was established way back in 1974, and was one of the first (if not the first) dedicated fault-tolerant computing companies.  They designed completely custom computers designed for use in high reliability transaction processing environments.  These were used for support of stock exchanges, banks, ATM networks, telephone/communications interchanges, and other areas where a computer failure would result in significant, costly, disruptions to business services.  Tandem was started by James Treybig, formally of HP, and a team he lured away from HP’s 3000 computer line.

Tandem computers are designed to do two things well, fail-over quickly when a failed part is detected.  This means that if a faulty processor or memory element is found, it can be automatically disabled, and processing continues, uninterrupted, on the rest of the system.  The other design element that Tandem perfected was allowing the computer to find and isolate intermittent problems.  If a processor or storage element ceases to work, that is relatively easy to figure out, but if a processor is glitchy, causing errors only occasionally, that can be much harder to find and can result in serious problems for the user.  This is known as ‘Fast Fail’ and today is a pretty standard concept, find the error, catch it, and prevent erroneous data from ever making it back into the database.  Tandem computers were designed from the ground up to be fault tolerant, disks were mirrors, power supplies, busses,

Tandem CLX 600 PCB (click for larger)

processors,all were redundant, but unlike some other systems, components were not kept as ‘hot spares’ sitting idle until something failed.  This kept hardware from being ‘wasted.’ Under normal operation if it was in the system, it was contributing to system performance.  A failed component then would reduce system performance until it was replaced/fixed, but a customer would not be paying for hardware that served them no purpose unless something broke.

To support these goals Tandem designed their own processors and instruction set architecture know as TNS (Tandem NonStop).  The first processors were a 16-bit design call the T/16 (later branded NonStop I) made out of TTL and SRAM chips spanning 2 PCBs.  Performance was around 0.7MIPS in 1976.  They were a stack based design similar to the HP3000 with added registers as well.  T/16 systems supported 2-16 processors. NonStop II, released in 1981, was similar, but supported the occasional 32-bit addressing, increasing accessible memory form 1 to 2MB per CPU and performance to 0.8MIPS.

The 1983 introduction of TXP saw a great performance improvement, up to 2.0 MIPS, but kept the same form factor.  The processor was implemented in TTL, with the addition of many PALs and added much better support for 32-bit addressing.  In 1986 the NonStop VLX was released, which moved to an ECL based processor.  This was a full 32-bit design, running at 12MHz (3MIPS) but still using discrete components and a new bus system as well.  This was to be the high end of the NonStop line, it was fast reliable, and rather large.  The desire for a more economical system to fit the needs of smaller customers led to a first for Tandem…

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Itanium Sales Forecasts vs Reality

‘Itanium is dead’ is a phrase that has been used for over a decade, in fact many claimed that the Itanium experiment was dead before it even launched in 2001.  The last hold-out of the Itanium architecture was HP, likely because the Itanium had a lot in common with its own PA-RISC.  However HP has announced that they will be transitioning their NonStop sever series to x86, presumably the new 15-core Xeons Intel is developing.  Itanium was launched with goal of storming the server market, billed as the next greatest thing, it failed to make the inroads expected, largely due to the 2 decades of x86 code it didnt support, and poor initial compiler support.  Many things were learned from Itanium so though it will become but a footnote, its technology will live on.

Interestingly other architectures that seemed to be n the brink are getting continued support in new chips.  Imagination, known for their graphics IP, purchased MIPS, and now has announced the MIPS Warrior P-class core.  This core supports speeds of over 2GHz, and is the first MIPS core with 128 bit SIMD support.

Broadcom, historically a MIPS powerhouse, has announced a 64-bit ARM server class processor with speeds of up to 3GHz. Perhaps ironic that ARM is now being introduced into a market that Itanium was designed for. Broadcom has an ARM Architecture license, meaning they can roll their own designs that implement the ARM instruction set, similar to Qualcomm and several others.

POWER continues to show its remarkable flexibility.  Used by IBM in larger mainframes in the POWER7 and POWER8 implementations it crunches data at speeds up to 4.4GHz.  On the other end of the spectrum, Freescale (formerly Motorola, one of the developers of the POWER architecture) has announced the 1.8GHz quad-core QorIQ T2080 for control applications such as networking, and other embedded use.  These days the POWER architecture is not often talked about, at least in the embedded market, but it continues to soldier on and be widely used.  LSI has used it in their Fusion-MPT RAID controllers, Xilinx continues to offer it embedded in FPGAs and BAE continues to offer it in the form of the RAD750 for space-based applications.

Perhaps it is this flexibility of use that has continued to allow architectures to be used.  Itanium was very focused, and did its one job very well. Same goes for the Alpha architecture, and the Intel i860, all of which are now discontinued.  ARM, MIPS, POWER, x86 and a host of MCU architectures continue to be used because of their flexibility and large code bases.

So what architecture will be next to fall? And will a truly new architecture be introduced that has the power and flexibility to stick around?

CNet Blog nanotech recently did an article about the 3 most recent CPU design flops by Intel, IBM, and AMD.

For Intel they chose the Itanium, and Itanium 2, there is no doubt that the Itanic as it is commonly called was a failure of epic proportions. It cost to much, and ad NO decent backwards compatibility and no existing code base.  Intel of course still keeps plugging away on it.

For AMD editor Brooke chose the Puma, AMD’s much hyped and highly underperforming CPU/GPU, no argument here, it was and is a dog.

Where I disagree is the selection of the PowerPC by IBM.  While Apple’s use of the PowerPC (all 10 years of it) ultimately ended in failure, the PowerPC did find its niche in many industries.  Servers and supercomputers worldwide use thousands of PowerPC CPU’s.  IBM has created many embedded versions which are used in everything from industrial control to running printers.  IBM has also successfully license the PowerPC architecture to many other companies (over 20 at that, including a couple CPU’s running on Mars). Xilinx makes FPGA’s with multiple integrated PowerPC cores which find there way into about everything. Apple continues to be involved in PowerPC through their purchase of PA Semiconductor.

Perhaps the most well known users of the PowerPC today? The Nintendo Wii and the XBOX 360.