Wednesday, May 3, 2006

Texas Instruments OMAP850

I can imagine the cries of dispair when the HTC Wizard was announced last year, that it would be powered by a Texas Instruments ARM processor. This especially after the debacle that was the HP iPAQ h6315. After using the Wizard for a week now, I can say that while the OMAP850 processor on the Wizard is only clocked at 200Mhz, it is speedy enough.

It isn't as fast as the 624Mhz processor on the Axim x50v, but it feels just slightly slower than Jennifer's HTC Magician (which has a 416Mhz Intel XScale PXA272 and a slightly unbloated OS). Put it this way, it feels twice as fast as my old Toshiba e310 with its Intel StrongARM 206Mhz. And that is with the bloated Windows Mobile 5.0 OS.

Specifically the OMAP850 contains two cores, an ARM926 application processor from ARM's family of ARM9E cores and a TI EDGE digital baseband chipset, the TCS3500 (an ARM7MCU coupled with Texas Instruments C54 DSP). Basically the workload of the Wizard (or any mobile device that uses the 850) is thus divided into the two cores (with some shared) as you can see from the diagram below (from Texas Instruments):

The ARM926 core controls the WiFi module, Infrared, LCD, buzzer, SD/MMC flash card and SDIO modules, LCD backlight, USB connection, battery, camera, LEDs and GPS (The Wizard doesn't have one).

As Windows Mobile 5.0 is a multi-task processor, processors has to divide up between the phone part of the OS and the PDA part. Receiving a call could slow the device down considerably, but the 3500 DSP is specifically there to deal with GSM calls.

It also controls EDGE data communications, although my service provider (o2 UK) has no EDGE network, so that is useless to me (Orange is the only network to offer EDGE in the UK). The DSP also handles the AC97 audio controller, SIM card, touch screen controller and part of the Bluetooth (voice), as well as the speakers.

Both of the cores share the load on memory controller, 2D graphic accelerator, keyboard and data Bluetooth.

The only slow down I noticed is when playing DivX encoded videos (above 500kbps and it would stutter) but overclocking to 240Mhz using OmapClock would sort it. Even sophisticated 3D games like Michael Schumacher Racing World Kart 2002 ran well. So don't sweat if the device you want contains a OMAP850.

But speed is a subjective matter, and what may seem okay to me may not be okay for you. You should trial any device to see if it fits. Don't let the stores pester you to purchase something. Stay as long as you want and force them to demo the units you want to purchase and make sure they have a reasonable return/exchange policy should you change your mind.

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