Terry Floyd, founder and chairman of the Support Group, tossed off a guess of 10,000 HP 3000s running worldwide today. His estimate runs just about midway between the highest number we've heard and one of the lowest, 700 companies. When we shared that estimate with Stromasys, they admitted to feeling a rock in the pits of their stomachs. No one will ever know for certain how many systems still hum with 3000 applications this year, or next. HP lost track of its customers when it careened into reseller arrangements in the early '90s that were better suited to selling LaserJets.

What more, the census got even more murky when customers started dropping HP support in favor of independent companies, or even self-support. By the late 1990s more than a third of the estimated systems around the world operated outside HP support records. A few years later the majority of 3000s were being serviced by companies that didn't report anything to HP about client counts.

It's become a regular exploration for me to ask 3000-specific suppliers about the census. Pivital Solutions CEO Steve Suraci said last month that customers keep appearing that he figured were off the system. "A customer called who I figured was off the MRP GrowthPower product "for about 10 years. I found out they're now a pretty big company and they're still running GrowthPower."

Floyd's company is finding 3000 sites like this, too. "We called and called a company that we thought would have a 3000 running, and got the answer no," said TSG's Donnie Poston. "But then we finally got to the right person, who said yes, they still had a 3000 in production."

Support companies, we figure, have the best chance of finding customers and 3000s in our transition era -- because they still have a service that adds value to owning a system. "There's quite a few of them out there that have always flown under HP's radar to begin with," Suraci said. "Vendors that have relied on HP for their customer lists never saw those customers in the first place."

At one point in the last four years, more than 500 HP 3000 were still in production at State Farm Insurance. These were well off of HP's supply radar, since State Farm loved to buy upgraded servers from independent brokers. One rumor we've heard, however, reported that State Farm bought more than 100 N-Class servers in 2006 -- direct from HP.

Whether there are 4,000-5,000 HP 3000s running around the world -- a popular guess -- or more than twice that begs a larger question. What's the correct number to call the market viable? In 1982, HP reported the entire universe was 10,000 servers, including some that were already out of service. That was a market that supported third party software, a user group exclusive to the 3000, a bi-monthly magazine and a dedicated sales force.

The marketplace is absolutely transformed today, but Stromasys is looking out beyond a time when the question about how many systems is still asked. Once HP ends its 3000 operations in about three months, the number of 3000 licenses is static. But then Stromasys may see unknown 3000 sites emerge which need an alternative to a migration, like the Series 917 users, as Suraci said, "who want to clean up what they have with an emulator [on a PC], so it's easier for an IT department to support them."

That emulator is scheduled to be rolling into customer sites almost 40 years after HP got started selling those 3000s. That prompts a question about another number, based on that history: How many years will companies want to maintain a choice that's still serving them well enough? If the sensible answer seems "as many as possible," maybe that lifespan is what the census takers really want to know.