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20051116 Wednesday November 16, 2005

IEEE ITC 2005, Austin - Test: Survival Of The Fittest

I am back from Austin, the live music capital of the world ... country ... a whole another country within a country ;) ... and here are the tunes I heard at the International Test Conference.

SUMMARY My personal focus was on microprocessor testing. Some key take-aways were: + Our competitors and partners have multi core SoC test problems on their minds (as expected). + Confirmed that cache preload is an established methodology for SoC functional testing in the industry. + There was an expected buzz about delay fault testing and compression. + No one seems to have been successful in taking transition tests to the extent that it replaces functional testing. Functional tests continue to rule their niche; while transition tests continue to enhance their value in production. + The most interesting papers on high speed serial interfaces were from our own team(s). + (personal opinion) For my first ITC experience, the overall paper quality was below expectations.

TUTORIAL: Dealing with timing issues in sub--100nm designs Li-C. Wang,UCSB and Magdy S. Abadir, Freescale

This tutorial primarily covered two sub-areas: Statistical STA and speed binning. Semiconductor metrology, modeling and variability decomposition were presented in a consolidated effort. Related issues from process characterization to speed binning were highlighted.

SSTA refers to timing analysis engines using statistical cell delay models with distribution functions as an input, as opposed to worst case STA cell delay models. Methods for model extraction were covered. A comparative motivation for SSTA was presented that showed a refinement in delay margin compared to worst case. A DAC 05 paper reference showed an SSTA application where the error in computing the standard deviation of the delay margin was on average only 0.19% of the measured path delay; on a large microprocessor block (> 100K cells, 90nm, 492 critical paths). Inclusion methods for power noise were proposed.

For speed binning, Freescale data was presented that showed that complex (through memory) transition tests give the best correlation to functional frequencies. Miscorrelation contributors, including higher switching with TT were mentioned.

STA generated critical paths do not always correlate to post-silicon speed paths. Path delay test helps define a correlation metric. Better correlation to Fmax was achieved by targeting individual paths instead of the entire path delay test set.

SESSION 6: Microprocessor Test

6.1: Testability Features of the First -Generation CELL Processor M. Riley, L. Bushard, N. Chelstrom, S. Ferguson, IBM; N. Kiryu, Toshiba Corp.

This presentation was nothing but a list of the testability features. Yet, there were a few items of interest to denote with more details in the paper. + The processor has a high speed asynchronous interconnect to memory and system io + IO and memory clocks are used in a synchronous mode during scan test + 46% of the logic is non scannable to save area and power + partial cores are supported + Single clock scan design with Thold_b clock control + Test modes: Full Access (scan), LBIST, OPMISR, ABIST, AVP, SST (Specialized Scan), IO, Free Run + Advanced Verification Program: functional test execution by loading memory + Modes are combined for test sequences

6.2: Test Methodology for Freescale's e600 core based on PowerPC N. Tendolkar, D. Belete, A. Razdan, H. Reyes, B. Schwarz, M. Sullivan, Freescale Semiconductor

This presentation was a variant of a previous paper and was not too interesting beyond the emphasis on LBIST and at-speed scan. The methodology includes an array clock freeze mode where outputs are driven to a fixed value.

6.3 Drive only at speed functional testing DOFT: One of the techniques Intel is using to control test cost Mike Tripp, Silvio Picano, Baruch Schnarch, Intel Corp.

As the title suggests, the ATE drives the stimulus and the response is either compared to the expected response on the device-under-test (DUT), or compressed into a signature on the DUT. The output of the comparison or signature is driven out of a test port for pass / fail determination by the ATE.

DOFT enables low cost tester usage, efficient use of tester memory (by 20-50%), reduces tester turn-around time limitations, and supports multi-site testing. The ATE could also drive the expected response in addition to the stimulus, and the two could be internally compared on the DUT(s) with DUT drivers tri-stated. A Signature mode is used on Pentium M, with efforts in place to eliminate X states.

The Signature mode is also used on the 65 nm Pentium-4. A DOFT like methodology could also be leveraged with future processor architectures with multiple cores, and with high speed asynchronous serial interfaces with external loopback relays.

PANEL 6: Have we addressed challenges for SoC testing ? Moderator: S. Menon, Intel, Panel: Y. Zorian, Virage, T. Wood, AMD, N. Chelstorm IBM, Raj Raina, Freescale.

This panel discussion was the highlight for me at ITC05; the reason being that there was representation from all major SoC microprocessor companies under one roof. The discussion covered SoC and / or multi-core testing. It was obvious from the discussion that SoC testing is still a challenge for the industry. The strategy followed is to divide and conquer using structural / BIST techniques, at least for production. IEEE Std. 1500 Testability Method for Embedded Core based ICs, seemed to be widely referenced or utilized.

The Q&A revolved around the following topics: + speed guarantee testing (was relegated to systems at AMD) + partial core testing strategies + non/availability of yield predictors based on partial cores / die size. + reliability of tested good cores with defective cores on chip + true array speed determination using MBIST and related design margins for control & data paths + speed binning with the existence of asynchronous domains

There was an open call (from R. Raina) for papers and development of methodologies (beyond cache preload) that reuse SoC on-chip memory as tester memory in some form of BIST. In conclusion, there was a consensus on the fact that many problems still remain unresolved.

Other sessions attended, but lacking major points of interest to report, were: 11.1 Enhanced Launch-Off Capture Transition Fault testing 11.2 Methods for improving transition Fault Coverage Using broadside Tests 12.3 Automated Mapping Of Precomputed Module Level Test Sequences to Processor Instructions PANEL 4: Business Constraints Guide Test Decisions - Not Vice Versa 21.1 BIST for Molecular Electronics Based Nanofabrics 21.2 Defect oriented testing and Diagnosis of Digital ufluid based bio-chips 21.3 A new approach for Massive Parallel Scan Design 27.1 A comprehensive Production Solution for SATA based on AWG and Undersampling Advantest 6.5G Presentation Advantest CertiMax Demo 45.2 Programmable MBIST 45.3 Full-speed Field Programmable MBIST Controller (2005-11-16 15:16:00.0) Permalink Comments [0]

20051031 Monday October 31, 2005

Fall - Its The Season Of Microprocessors On The Road To Multicore! It was a big week for microprocessors at the Fall Processor Forum in San Jose, and I wish I could have been there. Reading the web bits and bytes covering the forum was close to overdosing on caffeine for the processor engineer. In my short 10 years in the arena, I can't remember the last time so many processors vied for center stage: PWRficient(TM) from P.A Semi on the dark (big blue) side of the architectural force, to Fujitsu's Sparc64 VI+ Jupiter, to my personal favorite - Niagara :) ... The traffic is getting busy on the road to multicore! Also resounding in the media was the Intel inside(R) sound with another Itanic groan. Intel delayed (Montecito) its dual-core Itanium, and announced plans to give the Xeon line an interconnect booster shot called 'Tigerton' (seemingly reactive to AMD's dual-core Opteron, and to replace the dead Whitefield). You probably knew all this. What is conspicuous and reassuring is the following of multicore roadmaps gathering behind the pied pipers like Sun. As they say - imitation is the best form of flattery! (2005-10-31 23:16:00.0) Permalink Comments [0]

20050815 Monday August 15, 2005

A Global Citizen's W.IF In my evangelistic journey, I referenced the Indian PM's speech to the National Press Club. During the Q&A, the PM emphasized on the need for India to increase its IT investment in the area of hardware. An article from Infoworld - 'Sun invests in India ...' is good news from Sun India, coincidentally commemorating India's Independence Day. It is tempting to put the two together, and wonder whether in the not so distant future Sun hardware engineers will have the option to continue their work on cutting edge CMT microprocessors and systems at the IEC. No, not all the hardware jobs pals! Maybe just the existing Indian percentage. W(hat)IF the world is flat ? (2005-08-15 22:25:59.0) Permalink Comments [0]

20050807 Sunday August 07, 2005

58.2°N, 135.78°W and Thereabouts This is my debut blog, and an attempt to put into words a transcendental experience at Point Adolphus. Couldn't do justice without the verbosity ...

Watching the movie Whale Rider had nothing to do with our aspirations to paddle with the whales in their natural surroundings. It must be those prolonged hours of exposure to the nature channels on cable. The fact must be that Supriya and I both overdosed on the same subliminal messages from the idiot box. A taste for the outdoors, and love for the flora and fauna on the third rock from the sun - that's our common trait. After burning a lot of midnight oil over travel books, and travel web sites, we resolved on being frugal with our time allowance. We planned on spending the available eight days and seven nights in the not so tiny south east region of the "great land", or 'Alyeska'.

The Inside Passage extends along the Alaskan panhandle for about 900 miles north of Vancouver, British Columbia. A labyrinth of jagged coastlines, fjords, islands, sounds, glaciers, protected bays and straits that were once home to the native Tlingit and Haida. As per local mythology, it is the Haida inhabitants, of what is now Queen Charlotte Islands, who were taught how to build a canoe by the Raven. Their northwestern neighbors, the Eskimos and Aleuts, probably influenced the use of a kayak in the southeast. The kayak is an amazing human invention, or possibly a supernatural creation, like the canoe. It has only evolved in building materials; from the usage of animal skin and bones, to stronger, reliable, available, and humane synthetics. The Eskimos have been known to traverse the entire Arctic Circle, and reach as far down south as California in these extremely nimble and seaworthy skin covered boats. The Passage is brimming with natural opulence. The land is carved by ancient tidal glaciers; reminders of the last ice age, as they mark their paths towards the coastal waters. The areas emancipated by the glaciers have since been carpeted by lush green rain forests. And then there is the ocean; the richest of them all.

We jump-started our experience in the recently formed township of Gustavus. It is the gateway to the Glacier Bay, a World Heritage site. Our itinerary and priorities could not accommodate a visit to the Glacier Bay National Park, but Gustavus was a perfect launch site for our journey.

Gustavus is almost a town. It is a community of less than 400 permanent year round residents; with its origins as a homestead. The transients describe the aggregate of dwellings and its dwellers as a place "where the ordinary are extraordinary". We were picked up from the surprisingly developed airstrip by the only cab company in town, in what was probably the only cab in town. In summer, the airport supports a daily fifteen minute jet hop from Juneau. This was notoriously advertised by the airline steward as the second shortest jet flight in the nation. The rest of the traffic comprises of bush planes and float planes. Since no roads lead to this gateway town, your only other mode of transportation is by water, along the Alaskan Marine Highway.

Our lodge was rumored to be built by the owner herself, a peppered hair alumnus from Berkeley. The interior was comparable to a well-equipped urban studio apartment. A room with a view, placed amongst grassy fields speckled with native wild flowers, Indian Paintbrush and Fireweed; stretching towards sand banks and the bay on one side, and a majestically parading snow capped mountain range on the other. The high peaks keeping their snow, even during the warmer summer when the temperature ranges from 50°F to 60°F or higher at sea level.

The quaint little town is literally at the crossroads of change. It is a scattering of dwellings and establishments around the crossroads, with its only gas station at the junction. Change is visible in the form of another building under construction at the junction; expected to house three small stores. This must be to promote fair trade, because the only existing store in town is a grocery store and deli, west of the junction, on the way to the dock. We walked east from the junction in search of dinner at the only bed-and-breakfast cafe open in town, on a Sunday.

Unfortunately, we had missed the daily reservation deadline at an inn famous for it's family style local cuisine, cooked by the chef and inn keeper whose culinary skills are mentioned in the book '1000 Places To Go Before You Die'; under the worthier listing for Glacier Bay / Inside Passage. Dinner at the bed-and-breakfast was the freshest Alaskan salmon you can get on land. Coincidentally we were prearranged to move to this lodging for our second night's stay, as our room with a view had been accidentally overbooked. The hostess at the bed-and-breakfast proved to be psychic in recognizing us at the dinner table. This wasn't the last of the psychic predictions made by the ladies of this town.

It rained that summer evening, as is typical for a rain forest region. We spent the evening in our cozy room, browsing through the library stacked with books on the region. Appropriately for the weather, the rest of the library was completed with mystery novels donated by our hostess' sister from Seattle. I caught a glimpse of the land's natural and social history. This was the pictorial history of the natives; and the Russians, who by all means possible coaxed the natives to hunt some of the land's natural gems close to extinction; to the Alaskan land sale; followed by the Klondike gold rush. I traveled back in time through the pictures on maritime history, and it's fight with natural forces on the high seas. I read about marine biologists tracking Orca for the last few decades, and recognizing them by their fins and saddle pad markings. These magnificent marine mammals too could be differentiated as transients or residents, akin to their mammalian human counterparts of the region.

The next day was Independence Day, and our hostess predicted that the sun would break through the clouds, as it did every year to save the town parade. It did by parade time. What other option did the sun have in a town "where the ordinary are extraordinary". The epicenter of the parade was the bridge over Salmon River, and the park besides it. Almost every transient or resident, and visitor in Gustavus was here to cheer on the Hootchie-Cootchie band leading the town's fire engine with blaring sirens, followed by boisterously noisier kids and teenagers in honking jalopies. The parade culminated with a flyby salute by local pilots. A hot dog and burger lunch, games, a crab and halibut dinner, and finally an auction of donations by local artisans, writers and establishments followed this. It was during lunch that we were spotted and recognized again. This time by one of the owners of the excursion outfitters we were using for the next three days. We'd only exchanged emails and had phone conversations before. The world just gets smaller in this nascent town. In between these activities, we saddled up and peddled down in every direction the crossroads took us. By the time we got back for dinner, we had explored the town's beaches, dock, and what was it's waterfront nine hole golf course with overgrown weeds, wild strawberries for the picking, and an abandoned and rusty Chevy truck. This real estate was purchased a few years back, with plans for grandeur. But Mother Nature had other plans. The waterfront has since been receding along with the neighboring glaciers, leaving the golf course higher and drier. We returned for dinner, and then had to leave the festivities to get back to our lodging and keep an orientation appointment with our excursion guide, Spiritwalker Jon; and pack our dry bags for the ensuing expedition.

The day started early with a hearty breakfast, when Jon, an English teacher from Oregon and a summer transient in Gustavus, arrived with the van. All excited and packed, we were on our way to the docks. A few fishing boats were coming in with the early morning catch. The skies were cloudy, and the water was calm. Greeting us at the dock post was a magnificent bald eagle, perched on its throne, regally surveying the shallow waters for an edible opportunity. Jostling up and down the steel ramp with some industrious and some agitated fishermen, we formed a human chain and loaded our gear and kayaks onto our charter boat. Our boat captain was a friendly local charter fisherman, helped by his daughter, and a friendly little mutt in tow. With our rain gear on, we skimmed and bobbed over the seven nautical miles across the Icy Strait to Chichagof Island.

Chichagof Island has a unique coastline. It meanders in and out, creating a seemingly endless stretch of coves, beaches, inlets, bays, and peninsulas. This gives the island a coastline longer than all the Hawaiian Islands put together. Our premeditated destination was Eagles Beach, between Point Adolphus and Mud Bay. But the site was already occupied. Such popularity was a rarity. We simply chose the next beach over. The captain cut off the engines; carefully and deftly steering the boat ashore with the tide. Gently grounding the starboard side, we jumped overboard into the ankle deep icy water, but comfortably protected by our rubber boots. Using our well rehearsed human chain, our gear was quickly unloaded before the boat returned.

The strategy for our wilderness habitat was to follow a delta floor plan. Tent sites were at one point of a triangle, just behind the tree line; food storage straight across from the tents, on a potentially bear safe tree limb, more than ten feet above the ground; and a temporary kitchen at the triangle's apex, on an inter-tidal beach spot. The prime objective of this strategy was to avoid the habituation of the local grizzlies to humans as food providers. The unspoken cardinal rule was to avoid leaving human imprints on this pristine spot.

The spellbinding surroundings immediately welcomed you home. The spruce canopy was our roof, and the rocky and steep hillside our back wall. The spruce trunks were our doors, opening out onto a grassy doormat, with the pebbled beach as our yard with an outdoor kitchen. Just looking out onto the waters of the Icy Strait made one forget all connections to the civilized world. As far as the eye could see, we were in a water world, where the ocean, sky and land were all painted a similar shade that dissolved into each other at the horizon - like siblings embracing theirs mother's legs in a familial huddle. The ocean was a calm mercurial sheet, reflecting the ice-capped slopes and the cloudy gray sky. There was water everywhere, in one of its amazing forms or the other. This was Mother Nature's playground, and we felt privileged to be here, and overwhelmed by her affluence. The water, though calm, was teeming with life. The low tide divulged signs of a kelp forest under its surface. There were salmon playfully jumping in all directions around us. Sea lions bobbed their heads, curious and on the lookout for the sprightful fish. The orchestrated activity was joined in by the bald eagles, leaving their high tree top perch on frequent sorties and dives in search of food. Their mission was not complete until they successfully carried their catch back to their nesting and hungry eaglets; for they had to ward off attacks from other scavenging eagles and ravens. In avian contradiction, murrelets bobbed on the placid waters, pecking its surface for smaller prey like herring and krill. The currents from the open seas, weave their way between the islets, and churn the nutrient rich marine waters. This lures the humpback whales here to feed all summer. "Whoosh!" The jettison sound perked our ears, as our eyes scanned the waters. A few hundred yards away, a whale pod arched through the water, periodically surfacing and spouting plumes into the air at about three hundred miles per hour. White bottomed flukes and pectorals emerged and slammed the surface, followed by thunderous claps. The sensory indulgence was naturally aspirating to the mind and soul. The solitude was only broken by the odd fishing vessel, private yacht, magnetized tourist boat, or one of a couple of luxury behemoths allowed to navigate parts of the bay everyday.

We packed lunch, and paddled south towards Point Adolphus, cutting through the timid shore currents and calm wind with ease. With whales on our port side, we were finally satisfying our aspirations. It was tough resisting the urge to break the rules, and get closer than the stipulated hundred yards from these amazing mammals. The curious sea lions, not bothering to keep their distance, bobbed their heads and barked, and at times seemed to mimic the spouting and arching humpbacks. After lunch and a respite at Point Adolphus, we paddled back to camp, with the whales and sea lions for company. We had dinner watching the nature channel, live, as a nonchalant scraggly mink walked across the beach, scouting for tidal food in between the rocks. After dinner, we absorbed the tunes of the humpback orchestra, as their foghorns and splashes cut through the silence, like a marching percussion and trumpet band. The sun set over the horizon and beyond the Fairweather range, but the strait was still abuzz in the prolonged hours of summer twilight. We were sipping our wine, swatting away Noseeums, and giving up on preventing Beach Hopper protein from diving into our cups, when it started drizzling. As soon as we managed to get into our tents and sleeping bags, it started pouring. The operatic performance reached a crescendo that night, with the rain drumming on our tents as drops plummeted from the canopy, intermingled with the sixteen foot tide almost lapping at our feet, and the resounding humpback bass above and beyond them all.

The storm had passed over by breakfast time, leaving behind a totally different vista. The entire land was basking in an invigorating splash of sunshine, and the playground was abuzz with renewed energy. We decided to warm up with a short hike. Jon led us up the rocks and into the forest on what turned out to be a bear trail starting right behind our tent. This revelation added more substance to our anxiety levels the previous night, when each one of us had our ears perked like guard dogs, before the rhythm of the night coaxed us into a deep slumber. We ducked under broken branches that indicated the grizzly's stature, tracing its route; and dodged the animal's scat and prey bones, since cleansed dry. We continued on, suppressing the thorny Devil's Club leaves in our path, with our elbows. A few eagle feathers lay strewn on the rain forest floor, shed from the elevated roof nests. The trail led along a cliff that gave us an eagle eye view of the ocean and beach below. We descended, watching our step, down to the beach and walked back to base camp. It was time to pack lunch and paddle further south beyond Point Adolphus, towards Pinta Point. The tide was low and we had to skim our paddles over the kelp. The marine playground activities were at their peak, and were joined by sea otters, feeding and basking in the sunshine. We seemed to follow the whale pod everywhere. It was on the way back that we had our closest visual contact with these amazing and gentle leviathans. These gigantic mammals, averaging more than fifty tons and an equivalent number of feet in length, travel through the waters at unexpected speeds. They seemed to have avoided the tourist boats in the distance, and appeared about a whale's length from starboard. We stopped paddling and sat there in the water, transfixed by the sight. To see such a being lift itself out of the water and breach was spectacular and bewildering. The crashing of the flukes and pectorals, their lateral twists, the sight of their dorsals as they arched up and down through the water, the grace, the agility; it was music in motion. We were spiritually touched. Our eyes followed them as they distanced themselves, leaving us humbled.

Back at camp, we had acquired neighbors at the far southern end of the beach, who were paddling from Pelican to Hoonah, en route for the last two weeks. Our social exchanges included a freshly caught halibut for some wine and brownies. After skinning the fish and washing it in the nearby stream, Jon whipped up a hearty meal. Dinner was accompanied by an encore performance by our marine neighbors, amidst a spectacular sunset over the golden blue horizon. We woke up to a breezy morning, watching our neighbors fight the tide and head wind as they paddled south. We decided to brave the elements too, and then realized that it was quite an exertion. It took us a couple of hours to paddle a short distance, and less than half the time for the return. Having the tide and wind behind us, we explored the coast northwards towards Mud Bay. This was our last experience with the humpbacks of Point Adolphus and the Icy Strait, before we broke camp and headed back to the corporeal mainland.

The sun, rain and the wind made our stay memorable, but it was the humpbacks that left an eternal imprint when they touched our spirits.

(2005-08-07 23:10:48.0) Permalink Comments [0]


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