Everything You Wanted to Know About SDRAM Synchronization But Were Afraid to Ask

One of the problems with engagement in our hobby or profession is that people assume that if you can build a computer from chips, you must know every detail of their latest laptop. Most of the memory we deal with is pretty simple compared to DDR4 memory and if you've ever tried to tweak your memory, you know that a good BIOS has dozens of settings for memory. [Actually Hardcore Overclocking] has a great description of a typical DDR4 spec sheet and you can watch it in the video below.

Of course, he points out that knowing all of this really doesn't help you much with memory overclocking because you can't really predict complex effects without trial and error. However, most of us like to figure out which buttons we turn at random. Besides that, a theme of the video is that DRAM is dumb and simple. If you've ever thought of using it in a project, this might be a good place to start.

After all, there are only 18 commands, far less than a typical microcontroller. If you're interested in self-design, you'll be a bit disappointed that it doesn't cover self-refresh and power-saving modes, but the video will give you a good base to start learning more about.

Even out of the 18 commands, to read and write you only need a small number of commands. However, if you want to roll your own, you will need several. If you're targeting an FPGA, there are a number of FPGA-based controllers like this that can help you learn even more.

Remember that DDR5 is going to require you to buy new RAM soon enough and then you will have plenty of spare DDR4. Of course these days you might prefer to design around NVMe, which is a kind of memory and a kind of disk drive.