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Buying Handhelds Without an OS?
cr0sh asks: "I have a question that I am hoping someone can answer - today I was looking into cheap handhelds - I first looked at Palm, then at Handspring, then at something called LinuxDA, which seems to be a company offering not only an embedded Linux for handhelds, but also a device with it pre-loaded as one of their products. Looking at each of these companies offerings, I began to notice how they all seemed to be identical, hardware-wise (case, processor, button-layout, memory size, etc), so my question is - is there some company in Asia making the hardware, which each of these companies now source from, with the difference being the software on the platform? Handspring was kinda "spun-off" (not in the traditional sense) of Palm, but what is LinuxDA? The hardware they have looks the same, and their software can run on Palm devices. They surely didn't design and built their own hardware, and besides, each of these companies having such similar designs would cause them to lob trademark infringement lawsuits around - but they aren't - that only leaves the option of one of them acting as the source for the hardware, or an outside supplier. Basically, I want to know where I could get the bare hardware..."
Uh, having worked at one of the companies you mention, I can definately tell you that they designed their own systems from scratch.
Sure, for most Palm devices, the processors are the same - Palm OS runs on Dragonballs, at least until Palm OS 5.0 comes out. And you know, memory's memory. LCD screens are made by several manufacturers, I'd assume, as are buttons and such, but since the devices run the same (lightweight) OS, they're bound to be pretty similar inside.
The hard part is fitting it all together into the form factor, and adding whatever extra functionality your version offers. Those things are crammed _very_ tight.
But no, there's no mysterious reference design for this stuff; it's like saying all x86 manufacturer's motherboards can run the same code, and therefore they must all be supplied from the same source.
A basic PDA circuit diagram is pretty straightforward. RAM, ROM, CPU, LCD interface, LCD, button interface, buttons. If it weren't for the size, cost, and other design constraints, a second-year EE student could design a bare-bones system.