|VIA's Glenn Henry Speaks On New Low Power Isaiah Processor|
With all the buzz around VIA's recent announcement of their next generation low power Isaiah mobile processor and the parade of online coverage of the recent press event VIA held at their Centaur design center in Texas, we felt rather than regurgitating the usual marketing fluff and press pitch material, we would get together with some of VIA's top architecture and design brass in a "fireside chat" sort of venue. The idea was to provide a little more insight into what the team at VIA feels will be the real value proposition of their ultra low power Isaiah mobile X86 processor and how the product will differentiate versus current and future offerings from the likes of Intel, AMD and others. Our direct line of contact was with VIA's Centaur design center president, Glenn Henry. Former Dell CTO and IBM Engineering Fellow, Glenn founded Centaur back in 1995 and the highly successful company has the lowest employee attrition rate in the industry - no small feat for a semiconductor design house.
Q: With more than triple the number of transistors, a larger die, and potentially higher frequencies, how was Centaur able to lower Isaiah’s TDP (thermal power design) in comparison to your C7 core? Is the power savings a direct result of using a 65nm manufacturing process, or are there specific design elements within the core that lend themselves to power savings?
Glenn Henry: There are many areas in the chip where we optimized the design to improve overall power consumption above and beyond what a 65nm manufacturing process brings. We worked on the power profile of the chip first and didn’t focus as much on increased clock speed. We looked at performance-per-watt and made that our priority and then tuned the design for performance. The new Isaiah CPU will consume only about as much power as our current C7 but offer significant performance increases of up to two times our C7 chip.
Q: You’ve stated that Isaiah based processors are likely to outperform Intel’s upcoming Silverthorne processor. What is it about Isaiah that gives it this perceived advantage? Is there a higher IPC capability in the design versus Intel’s architecture? What fundamental blocks of the chip offer you a competitive advantage, in your opinion.
Glenn Henry: Had I known that I would have gotten so much publicity for that statement, I may not have said it BUT, in a nutshell, we suspect Intel’s Silverthorne is an in-order processor (instruction fetch, operand dispatch, execution, and then function unit/result write). Isaiah is an out-of-order processor and out of order processors are just, faster. Isaiah is capable of three X86 instructions per clock and can execute up to 7 micro-instructions per clock with our superscalar architecture. They’ll (Intel) likely only be able to do 1 or 2 X86 instructions per clock. We also think our 1MB L2 Cache and dual 64K L1 caches going to be larger than theirs but we can’t confirm this officially obviously. So the big bullets are; out of order execution, a wider three-issue superscalar architecture and likely larger caches versus the other guy’s (Intel’s) chip – at least from what we think we know of their product at this point in time.
Glenn Henry: Isaiah's FPU performance is a big gain in some applications for sure. We’re relatively a lot faster on applications that are heavy on FPU but also lot faster than our previous product (C7) on integer operations. How we achieved greater FPU performance is a patentable invention. We came up with a new approach to doing floating-point adds and put a lot of detailed engineering work on FP multiplies. Centaur started working on the FPU architecture on the first day. It was something we didn’t do as well on the C7 but we made it a top priority on Isaiah and put a lot of focus on FPU performance.
Q: Is VIA / Centaur also developing lower power, higher performing chipsets for the Isaiah architecture to further enhance the entire platform’s power and thermal characteristics?
Glenn Henry: Yes, we can’t offer any info on the new chipsets right now but there will likely be a new chipset with the part when it launches. In addition, Isaiah will be compatible with our current chipsets, which will be a big advantage for our current customers in their migration efforts to Isaiah.
|Pin Compatibility, More Capable UMPCs and Ultra-Lights|
Q: Initial Isaiah based processors are said to be pin compatible with the C7, which will make it easy for partners to adopt them for existing designs. This leads us to believe a new pin-out is planned for future revisions of the core, however. If that is the case, can you comment on some of the new features that might come along with a new pin-out?
Glenn Henry: At this point we have no plans to bring out a new pin-out for the chip and there is no perceived need to take the design beyond our current footprint. In the future, if there’s some obvious market need, we would of course react to that.
Glenn Henry: You should probably talk to a few of our marketing guys on this one but personally, I don’t think we’ll see a new class of devices spring up from the introduction of Isaiah. However, we will make the existing laundry list of devices more functional and useful. Here’s a personal example. I have an OQO UPMC that runs Windows XP really well on our C7 processor. One of our Engineers here tried to install Vista on it and wasn’t happy at all with the performance. Vista just consumes a lot of processing power. I don’t want to say it’s a CPU hog (nah! why would he say that?) but this is just an example of how we’ll make current existing devices more capable and useful. So maybe they can process not just MPEG2 but also MPEG4 content and run Vista on these machines; stuff like that. Also, from our personal viewpoint, this chip will make us a lot more competitive in low-end desktops and notebooks. HP in China uses our C7 in a low cost desktop, for example and Isaiah will benefit them greatly by doubling their available performance.
Glenn Henry: I don’t want to quote anything on this topic because a large component of power consumption in ultra-mobile devices isn’t tied to CPU power consumption, so it would be hard to provide accurate projections. However, Isaiah consumes about the same amount of power as our current C7 processor. Where we’ll see big benefits will be in power efficiency. In other words, Isaiah will have higher overall processing throughput at relatively the same power consumption. So in that scenario, battery life should obviously be improved.
It’s too complicated to say though really. There aren’t very good benchmarks in this area though, so we’ll have to see how it performs in real-world applications first. If statistics are lies, so to speak, then quoting power statistics in this area early on would be a worse lie. So we don’t want to go there.
|Future Process Migrations, Interview Audio Download and FAQ|
Glenn Henry: We assume it will have a very long life cycle like the C7. We’ve done a lot of things in the design to leave hooks for adding new features and transition to new technology. We have a very small design team, so we architected the chip with a lot of flexibility in mind for adding future functionality and features.
Yes there are plans for a 45nm processor in the future and we’re actively working on it as we speak. We could technically take Isaiah to as low as fab technologies are capable. However, fab capitalization and costs for leading-edge fab processes are expensive. We won’t be on the leading edge out of principal, but will only move that way when there are obvious advantages.
Isaiah will come in a 21x21mm BGA package that is compatible with current C7 designs. We’ll also be introducing a much smaller 11x11mm package for both Isaiah and C7, with a tighter ball pitch of course. VIA has been showcasing a business card-sized full PC on their site with that 11mm package which is obviously very tiny. So the processor will be available in 11x11mm BGAs with a Northbridge/Graphics/Southbridge chip a single 25x25mm BGA. All told, that’s not a lot of real-estate at all.
Thanks very much for your time, Glenn. It was a pleasure. Good luck!