[A89] Re: Quite in here... let's discuss something!
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[A89] Re: Quite in here... let's discuss something!
> On HW2 calculators, the lcd dma doesn't affect the performance. This is
> because all writes to the led are snooped, and copied to a special buffer
> for the LCD (separate from normal ram). ie the dma doesn't have to
> constantly fetch the lcd data from ram and use the bus.... which leaves it
> free to do other stuff...
>
> That's all i know :)
FYI, last I checked TI considered the changes between the HW1 and HW2 LCDs
(using the hardware gate array as a buffer to eliminate the LCD DMA) to be
highly confidential. When one of their employees, not knowing it was a
secret, explained this a while back, he got in a lot of trouble. So
everything we know about the LCD DMA comes from that one message and a few
brave souls who opened up their calculators and took them apart =)
-Scott