PocketMatrix

cnet review: "3D interface of Windows CE 4.21"
did i miss something with SE? maybe a hidden feature? (or they are probably talking about the ipaq software...)

btw comparing X30 with hx4700 is kinda useless. it's two different category. i don't think anybody thought that a VGA device will outperform or even reach a top QVGA model in graphic speed (comparing with stuff that is not hw accelerated)

It's a bit inaccurate to say any VGA device will be slower. If you're playing games in QVGA mode you're still not going to get awful gameplay, just VGA games - ie games that are blitting to all 640x480 pixels.

Sponge: You are probably right. I believe optimized code can scale it by x2 for "free". Basically your bottleneck when scaling is reading the original image, not writting the scaled version. If this is true, you can paralellize the writting with the reading and your speed becomes that of reading the original image. So scaling or not, speed is about the same. But there is some bitshifting and instruction dependencies when scaling that are simply not there when doing a straightcopy. I would thus expect slightly slower performances.

Guest: what you are saying doesn't make any sense. The screen doesn't wait for the code to update pixels. The LCD update is done with a DMA transfer and doesn't interface with the code at all. That's actually the reason why there is tearing at high refresh rate and that there is no easy way to sync the screen update with the vblank period.

Guest: actually you don't have to wait for the lcd to draw the pixel. the lcd reads the video memory all the time with 60-70hz (for VGA it's quite big bandwidth 640x480x2x70 byte/sec). you simple write into the video memory and when the lcd scanline goes there next time it will be displayed.

but writing to memory takes time. if you check the specs even if the new pxa cpus has much higher main core frequency the memory bus is still about the same (100Mhz->104Mhz). many operation is memory speed limited. writing four times many pixels to memory can be slow.