EE Times Under the Hood - June 23, 2008 - (Page U50)

UTH0623COMP_pg42_55.qxd 6/11/08 4:32 PM Page 50 under the hood: w w w. e e t i m e s . c o m C OMPUT ERS & GAM I NG • w w w. t e c h o n l i n e . c o m Scientific calculator boils down to two ICs very once in a while I come across a product that makes me say, I’ve got to take that apart. That was the case with Hewlett-Packard Co.’s 35s scientific calculator. I spotted it sitting on another editor’s desk, in his own teardown queue. But because of my history with this product’s predecessors, I volunteered to write the story. BY RICHARD NASS E VIDEO For more insight, view the related TeardownTV episode at: cmptv.net/teardown/HP35s True, this is not the sexiest consumer product out there. Still, the engineering audience will likely see the appeal that the latest in a long line of HP scientific calculators held for me. The product arrived in time for the 35th anniversary of HP’s first scientific calculator. Hence, the “35” moniker. The 35s is similar in many ways to the 15c I bought 20-odd years ago when I entered engineering school (note that I paid about $125 for it, while the 35s sells for about $60). There’s no doubt that the 15c was the premier calculator of its time. Just about everybody in engineering school seemed to have one. I bet many of you are smiling to yourselves and saying, “Yeah, I bought one of those, too.” But the kicker—for me, and I’d bet for many of you—is that my 15c is still going strong. In fact, it still serves as my everyday calculator. And it doesn’t get borrowed, like many of the other objects on my desk, such as the tape dispenser, stapler and scissors, thanks to its use of reverse Polish notation (RPN). My family takes the attitude that it’s easier to find another calculator than to learn RPN. And that suits me just fine. The 35s can be used in either RPN or algebraic mode, although it defaults to RPN when you first turn it on. One big reason I wanted to take the 35s apart was to see how the design had evolved over the years. While I wasn’t willing to destroy my 15c for the sake of this article, I did get some good insight from Sam Kim, the direc- tor of product development for HP’s calculator group, who claimed to be the force behind the 35s. Kim said he wasn’t satisfied with HP’s existing line of calculators. “I really wanted to design something for the old-time calculator user while also attracting new customers,” he said. Two key components In a sense, I was disappointed to see what was actually inside the calculator. That’s because it’s not a very interesting design. It’s just two key components—an 8502 microcontroller and a flash memory chip, both covered by a blob of epoxy. The processor is under the bigger blob. The 8502 is designed by Sunplus Technology, a Taiwanese company. It’s based on the 6502, an 8-bit processor that first appeared on the Commodore 64 computer, which was popular around the same time that I purchased my 15c. The flash memory is a generic part, and no specific vendor is used. It’s generally based on whatever is available at the right price at the right time. The 8502 that’s used here also contains the system’s power management and all the typical chip-set functions, including an LCD driver, a keyboard controller, and so on. Kim explained that my old 15c was built with a 4-bit processor and had very limited memory. However, it has the ability to perform matrix manipulation, a feature that was way before its time, at least in a handheld calculator. And it was programmable. With the design down to just the two main ICs, it quickly became clear 8502 microcontroller Flash memory chip The HP 35s scientific calculator consists of just two key components, an 8502 microcontroller (under the larger blob of epoxy) and a flash memory chip (under the small blob of epoxy) 50 Electronic Engineering Times, TechOnline | June 23, 2008 http://www.techonline.com http://www.eetimes.com http://cmptv.net/TearDownTV/HP35s

Table of Contents Feed for the Digital Edition of Under the Hood - June 23, 2008

Under the Hood - June 23, 2008 Extreme Design: SuitSat Pushes Desigers' Limits Evolution of the Smart Phone Mature Devices get Rolly Rocking GPS: Garmin Nuvi 750 vs. HP iPaq 310 Inside the Sony OLED TV Multizone Dgital Audio Flip Ultra Camcorder - An Ode to Clean Design Robot Guitar Tunes Itself E-book is a Sight for Sore Eyes Scientific Calculator Boils Down to Two ICs $100 BOM Eludes First OLPC Laptop 45 nm: What Intel Didn't Tell You Next Step in NAND Flash Evolution Surveillance on a Shoestring Hot 3G Phone Owes Debt to Analog SecurID Fob: Single-Chip Safety Net

Under the Hood - June 23, 2008

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