DMA - Direct Memory Access on the ZX Spectrum Next

This is the third video in a short series looking at some of the more advanced parts of the Spectrum Next. If you've not seen the others, go watch them after this one. In this video we're looking at how to program the DMA controller in the Spectrum Next. This'll be technical, it'll include code on how to do this using Z88DK and C for the Spectrum Next. It's a pretty advanced technique, but it's quite understandable and can add some nice speed boosts to code if used appropriately. DMA or Direct Memory Access is a way to allow devices access to system RAM without the CPU being involved. The DMA controller in the Next is a programmable device and has a few registers that need writing to. This is well documented on the Spectrum Next wiki https://wiki.specnext.dev/DMA. There are seven registers called WR0 to WR6. Writing to them is like when we configured the sprite system in my other video. Each register is accessed through the same IO port and the pattern of the first three bits tells