Earlier this year, Apple Inc. co-founder Steve Wozniak accepted the position of chief scientist at start-up solid-state drive company Fusion-io. It's the first time since 1972, when he worked in Hewlett-Packard Co.'s calculator division, that he has held a technologist's position for a company that wasn't his own.

Unlike many other solid-state vendors, Fusion-io doesn't manufacture a NAND flash drive product in a 2.5-in. or 3.5-in hard drive form factor. The company makes PCIe cards with up to 640GB of capacity and 1.6GB/sec. throughput that can be inserted directly into servers, greatly increasing performance for I/O-intensive applications while also shrinking space requirements when compared to high-end hard disk drives.

Since joining the company, Wozniak hasn't widely discussed why he chose to become a member of Fusion-io's advisory board and then its chief scientist. Computerworld spoke to him about that choice and what he sees as the future of solid-state storage technology. The following are excerpts from that interview.

Becoming a member of any company's board that you didn't help create seems uncharacteristic of you, so why did you join Fusion-io's? I joined because I saw a remarkable vision, but more than the product vision, I saw the people who created the vision. Their overall design methodologies lead to good clean products. That's what I saw in these people. I really expected to be invited to join the advisory board, but I sort of got a position in the company, which was exciting because by then I was so sold on the company.

And, I'm sort of a purist. I like things with electrons moving instead of heavy metal parts -- maybe because I didn't grow up as a mechanical person. Rather than spinning atoms, I like to get down to electrons, and who knows, maybe in the future it will be photons.

You've never really been a storage guy. What attracted you to this technology? Well, I was a storage guy really early - in floppy disks. I don't come from the heavy-duty storage area where you've got RAID arrays and fiber optic channels. But, actually, the way I approached even designing my floppy disk structures was to take out a lot of middle man technology that wasn't needed - to look at the overall problem and get from the start to the finish in one quick jump. And, I saw those same principles had been applied in designing [Fusion-io's] product.

Also, I've been close to a lot of people who worked in data centers -- good friends -- and it's just like data centers always have huge racks and racks of equipment. And, almost every entity in the world is basing its operations on servers and disk storage, so it's almost unlimited. So [with Fusion-io] you're not confined to one little niche.

What initially caught your eye, though? I went into a meeting totally blind. I hadn't researched the company. I had just agreed to have lunch in Los Gatos, [Calif.] with some of the engineers. I'd met a couple of really bright Ph.ds like [Fusion-io chief technology officer] David Flynn ... and his background was with supercomputers and disk storage devices. He'd worked a very long time with a low budget at home, sort of the way we'd done it at Apple and he had gotten far enough to have developed some very good working models. He didn't go down to a venture capitalist with a sheet of paper and say here's what we'd like to do and give away all the company to begin with. I really admired the way he'd structured his start-up.

I started asking questions like, how would it compare to this, or how would it compare to that technology? How did you solve these problems? The answers came back very knowledgeable and very much in line with my thinking about how you should design good products. They completed their financing round, which I had nothing to do with, and then they offered me a position in the company and I accepted. It's the first time I accepted a position in a company that I didn't create myself since 1972 with Hewlett-Packard calculators.

What do you see as the role of solid-state drives today and how do you see that changing over the next five to 10 years? I've been a very big fan of solid-state storage. I had dynamic RAMs backed up with power in huge tower-like structures that I'd connect to early Macintosh computers. I'd use that as my disk and it would double my speed. I've been a fan of solid-state disk in my laptops - I always ordered them and paid extra for the solid-state disk. I'm just sort of a purist. With music devices, even before the first iPod, I preferred to use solid-state storage when it cost a thousand dollars to have enough solid-state storage for an airplane flight. So, I'm just a big fan of that storage media.

Why? It's just really interesting to see at the enterprise level that it's outperforming and solving a lot of problems we're having with spinning media. It's a very different approach to how you solve your storage problems. I like to say solid-state storage, not solid-state disk, because a disk implies it's on a regular cable, plug-in structure that a disk could be plugged into and this is one alternative. I like skipping that and just going to just one protocol in communication.

SSD appears to be finding great success in enterprise-class server systems, but not so much in the PC and laptop market. Why is that? Hard disks over a certain size are still more economical than solid-state storage. You have to pay a premium to have solid-state storage, and depending on the way it's architected, it may not be faster in all ways. I have flash in my laptop and it boots up and loads programs much faster than before, but the general operation doesn't seem that much faster. So why would you pay extra when you don't see [the added performance]?

I mean I'd pay extra ... because I like the whole concept of reliability [with flash memory], and I like to be a purist and like to be a little bit in the lead in doing something. I like to have an early jump. So I had this penchant for solid-state storage before the fact that it now has a place in enterprise storage. That's what really surprised me, and of course now the whole world is recognizing that's a big part of the future of enterprise storage - at least on the first tier.

Why has solid-state storage done so well in the enterprise? There was a vacuum. The solution hadn't been recognized early on. Even the personal computer could be thought of but it couldn't be designed until the price of chips due to Moore's Law came down to a certain amount of power in chips for a certain price. In flash memory, that wasn't obvious at first - how low it would get. But as flash memory went into consumer devices [MP3 music players, USB flash drives, for example] and became such a huge product ... its price came down.

When I first talked to the Fusion-io people I asked how would it compare to a bunch of disk drives in a RAID array. And, how about in an enterprise server? And they said we beat them 2 to 1. I'm a practical person and I look at what really works and what doesn't, and it's incredible how much equipment they save and how much complexity they save and how much power they save. Almost everywhere I go ... I speak to CEOs of companies and when I tell them what our product does they say, "Oh, my god. We've got to get onto this right away." We've got the solution to so many problems that people are going through right now.

How do you see the PCIe form factor addressing the bottle neck issue between the CPU and the application as opposed to using SSD in a 2.5-in or 3.5-in disk form factor? I look at it as a more efficient, more direct connection to the high-speed bus. That's where you want it. The processors are so fast now, you've got so many cores, that they're no longer the bottleneck. It's always been the disk channel [that's been the bottleneck]. Sure, you can come close in bandwidth if you plug a Fibre Channel board into the same slot. But why do you want to transfer all your data into the Fibre Channel mode and then transfer it back. Why do you want to go through extra boards to cables to more boards and cables and then transfer it back? Skip all that middle-man stuff. That's the same way I thought when I was designing computers, storage and disks. Re-visualize the entire problem.

You want to get a little data from here to there, but you don't want to go through extra chips, extra parts, extra pieces. That's unreliability. The number of pins and connections you have is more related to reliability than the overall number of transistors these days.

I also like the fact that you just plug a board into a computer. I'm one of these guys that doesn't like to see bundles and bundles of cables. You know, where does this one go, and did I plug that one in the right way? Then you have to test both ends of it. It becomes a mess. I've got racks of equipment in my home and I don't like that. It's an overall mess that you look at and think, this scares away the common person. It scares away a child. I really believe that when you make something so simple that anyone can look at it and understand it, it even makes it easier for the engineers to understand what's going on where. That was one of the big things that turned me toward Fusion-io - using this form factor compared to the solid-state disk approach.

Do you see a day when solid-state storage will kick all spinning disk out of the data center? No. I don't see it kicking all spinning disks out. In computers we have so many tiers of storage for cost efficiency. Even when you have a hard disk drive it has its own cache built into it. Then we have caching systems in operating systems. Then we have different speeds of memory from your RAM to your L1, L2, L3 caches. This is an in-between one, but I think it's going to be huge - a lot bigger than people think. It cost more money per bit to create NAND flash ... [but] in a lot of places kick out spinning storage. I can see certainly in a netbook you don't want spinning storage. If you're talking 64GB or less, it's less expensive to have flash solid-state disk now.

But in a big enterprise-class data center there are huge amounts of data that aren't accessed very often. It's just mathematics. You take stuff that's not accessed very often, it can be accessed slowly. And then you bring it into a faster form of storage when it is being used a lot.

So I can see solid-state storage in the enterprise as a type of cache, without the same programming and design structure as cache, but serving that same purpose.

How will the maturing of the flash memory market affect the DRAM market? Do you think flash memory could replace DRAM as a type of cache in the future? Indirectly. When ... you have this high speed, local, very cost effective mass storage, all of a sudden you don't need this extra level of cache to speed it up because it's already fast enough to keep your processor at 100% efficiency.

Apple, like many personal computer manufacturers, has been slow to adopt flash in the majority of its desktops and laptops - at least not as something that doesn't come at a significant premium. How long before these companies start really warming up to flash and offering it at a reasonable price? I do remember paying a premium for it, but it was like the first computer I'd ever seen that offered flash from the factory as an option. That was the MacBook Air. So of course I ordered my Air with the 64GB flash option.

But now 64GB is the crossover point ... where it's equally expensive to have spinning disk or flash. So if your needs are met by 64GB, that's your decision today. Now, I look at my MacBook Pro, and I have a 256GB flash drive built in, and, yes, it cost me an extra $800. It gives me a little slicker performance but it's not a killer that everyone needs. I can't say Apple has held back that much. The new technology of the future, Apple's usually the earlier ones to jump on in recognizing what the winners are going to be. Things like USB, FireWire and a number of other such products over time.

When do you see the market for solid-state really catching fire? It's on fire now. I look back to the personal computer revolution, and we weren't selling many personal computers, but just as we were starting Apple, the first wave of analysts paying attention to this and saying it was going to be a multibillion-dollar market was so similar with what's happening with Fusion-io. Almost anywhere I go, I talk to anyone with a large company and when I tell them about our product and what it does, they want to get their IT people on it right away. It takes a long time before that turns into huge sales, but what other start-up company do you know that has 1,000 customers in a year?

I've been associated with an awful lot of start-ups, my own and others, and I've never seen one growing this fast and successfully since Apple.

So you're comparing this in many ways to what it was like with Steve Jobs and Apple in the early 1970s? If I didn't think it was very similar, I wouldn't be here. We're bringing the revolution to the world. We're looking at all the competition jumping into the same market. It's an exciting time in life again.