Having Been Human
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Sat Jul 21 05:21:23 2012
Bus Mastering and DMA

I learned about bus-mastering a loooong time ago; it's a pretty cool capability for hardware to take some burden off of the CPU. I had hardware that was capable of bus-mastering back then. More recently, I've had hardware that said it did DMA; I always assumed that DMA was basically the same thing.

Tonight I was curious to find out how true that is.

Turns out it's just about 75% true, and there are some important nuances in how the terms relate. I enjoyed reading this explanation to clear it up. Looks like DMA is done by hardware that does a limited, programmed subset of what bus mastering is broadly capable of, and DMA uses bus mastering as its underlying mechanism.

Also, earlier today I found that my cats have progressively dug a cat-shaped hole into my laundry basket. This would be irritating, but it's surprising enough that I'm actually kind of impressed.