Every once in a while we take a retro look at products to help calibrate the pace of change in consumer electronics. Particularly when there are modern parallels for the product category, a look at the past can be enlightening and (for me, anyway) a bit amusing. In tidying up the Portelligent "morgue," which has product teardowns dating back to the early 1990s, an old gem resurfaced: the Diamond Rio PMP300 MP3 player.

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A single-line LCD provided the visual interface, displaying only the track number. None of the modern expectations of artist and title information, album cover art or timing information was shown, but it was enough to get the job done. Much as is the case today, the control interface consisted of a circular set of buttons for backward and forward track skipping along with start, stop, pause and the option for repeat play and random mode. (Sound familiar?)

The PMP300 provided four different equalizer settings, and both MP2 and MP3 audio formats could be played. Support for multiple bit rates and variable-bit-rate MP3 was also standard. A SmartMedia slot gave the PMP300 an expansion path to a maximum of 64 Mbytes, with cards up to 32 Mbytes possible at the upper limit. A single AA alkaline cell powered the device for about 10 hours of average playback time and the host PC's parallel port gave means for interface and song upload.

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Along with breaking open a new consumer market, the PMP300 broke some new legal ground. In a courtroom scene that sounds like it could come from today's headlines, the Diamond Rio was the subject of a lawsuit filed by the Recording Industry Association of America, which claimed the player violated the 1992 Audio Home Recording Act. Diamond received a favorable ruling in October 1998, however, clearing the path for development of the MP3 player market.

So how was this pioneer product made? Surprisingly, the overall PMP300 architecture bears a resemblance to one of today's most popular flash-based players, the Apple Nano. Key elements of the PMP300 were built from the growing availability of affordable NAND flash memory devices, and here four Samsung packages with 8 Mbytes each (part number KM29U64000T) supplied the 32 Mbytes of total internal memory. As in some other modern players, a NAND memory interface was required, and here an Actel A40MX04, a 6,000-gate FPGA, created the gateway between NAND flash and the system controller, an NEC µPD78P064GC 8-bit microcontroller.

A Micronas MAS3507 MP3 decoder (actually a design from Intermetall, which was purchased by Micronas) provides for the system DSP, translating the compressed MP3 stored-media format to a flat, expanded digital-music equivalent. From there a Micronas/Intermetall MAS3550 digital-to-analog converter created the final analog output for delivery to the headphone jack.

Page 2: Under the Hood: The MP3 that broke new ground
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