Misinformation Department9 December 2002 I've seen a lot of confusion and misunderstanding in the mobile landscape recently. Here's a quick primer on some of the big issues and what you can do about them, or why you shouldn't worry about them in the first place. Hey, buddy, can you spare a NAND?It's a shame I didn't realize how NAND flash memory works when I wrote my Bargain Basement column, because it directly supports my "low-priced Pocket PCs as a gateway drug to higher-priced (and higher margin) Pocket PCs" theory. News hit recently that the $299 ViewSonic V35 has the same issue as the already-criticized HP iPAQ 1910, in that a fair chunk of the device's 64MB of RAM is unusable by the user. The ViewSonic V35 has about 36MB available to the user, while the HP 1910 has 46MB user-accessible. The reason behind this has to do with the difference between NAND and NOR flash memory. Older and higher-priced Pocket PCs use NOR flash memory to store the OS. This is more expensive than NAND memory, and slower to write, but it does have one significant advantage. It has a wide data pipe that allows the device to run the OS and applications directly from flash, called "executing in place," or XIP. This is why a 64MB Pocket PC like the Toshiba e335 (which uses NOR memory) has nearly 64MB free after a hard reset. The OS itself is running, but it's running directly from flash. NAND memory uses a serial pipe for data and can't support XIP. When a device using NAND memory starts up, it has to copy the OS and core apps into RAM and execute them from there. This is exactly the way PCs work, copying the OS from the hard drive to RAM before running it, and it's the reason you need both a hard drive and system RAM on a PC, rather than just one giant flash drive. NAND memory is significantly cheaper than NOR memory, though, and figures to be a popular choice in low-end Pocket PCs as a way to keep the price low and still make a profit on the device. (Remember that unlike cell phone makers, Pocket PC makers can't take a loss on the hardware and make it up in service costs.) This means that while the V35 and H1910 are advertised as being 64MB devices, they really aren't, at least not the same way 64MB devices using NOR are. The V35 is closer to being a 32MB device, while the H1910 comes in a little better. Does this mean that these devices are faulty, or not worth getting? Not at all! I've been a Pocket PC power user for many years now, the vast majority of that time using 32MB devices. It is possible to use a Pocket PC as your "do everything" device without 64MB of RAM. The key is liberal use of the storage card. I install almost everything to my 256MB SD card, almost never having more than 7MB used by storage in RAM. I have my device allocated with 20MB even of program memory and 11.21MB of storage memory. This is enough to run all the programs I need, even beasts like Adobe Acrobat. I use PocketNav to switch between tasks, and I periodically close apps I'm not using. Of course, there is a catch. Unlike my trusty 32MB XDA, the V35 and H1910 have no networking built in. If you want to connect the devices by some means other than IR or the cradle, you'll have to remove the memory card. This "network or expansion, but not both" drove me nuts on my Jornadas and will probably do the same to folks that buy the V35 or H1910. This is, of course, exactly what ViewSonic and HP are counting on. These $299 devices give folks a good taste of what Pocket PCs can do, but many users will inevitably "graduate" to the HP iPAQ H5450, an XDA, one of the dual-slot Toshibas, or the higher-end devices ViewSonic is planning for next year. Or, people might just buy a Dell Axim X5 from the start and be done with it... 300MHz, 400MHz, Whatever It TakesIt's all about bus speed. I've seen several folks comment on the slower processors of the Toshiba e335 (300MHz XScale) and iPAQ H1910 (200MHz XScale). Given that a 400MHz XScale gives roughly the same performance as a 206MHz StrongARM, these lesser XScale devices must be abysmally slow, right? Actually, no. For most things, all those XScale speeds will look more or less like a 206MHz StrongARM. The reason is that all the XScales use a 100MHz data bus, compared to the 103MHz data bus on the 206MHz StrongARM. I went over this in detail in XScale: Hit or Hype? in June. In short, the bottleneck for most Pocket PC performance is the data bus between the CPU and the rest of the system, not the CPU itself. While a 400MHz processor would be faster for something like number crunching, for most day to day activities (calendar, email, music, ebooks, etc.) a 200MHz XScale is going to be about as fast - perhaps slower, but only your benchmarking program knows for sure - as all the other XScales out there. So if you really want that 200MHz iPAQ H1910, go ahead and snag it (watch for my review of it next week). Your "need for speed" won't suffer too much. Jeff Kirvin
Jeff Kirvin is available for consulting on mobile technology. Email me today! |