lemmington_steeleWhy do SSDs have a more limited number of times data can be written to them, but RAM memory can handle loads of re-writes?
Writing to an SSD damages the SSD, however things saved to an SSD are persistent, meaning the data isn’t lost when the SSD doesn’t get any power. Writing to RAM doesn’t damage it and it is also quicker. However, data saved on RAM is not persistent, meaning that all data is lost as soon as the RAM is not connected to a power source. Also, RAM is a lot more expensive than SSD storage.
RAMs are already used to avoid writing to (or reading from) the SSD or HDD when possible, the concept is called “Caching”
Even if it's powered, RAM will lose its data on the order of a tenth of a second. RAM doesn't just require power, it requires that your computer constantly read and rewrite it - so every 64ms your computer has to read every gigabyte of RAM and write it back.
What!
rickdgrayDynamic RAM tracks bits by using a capacitor for each bit. Caps’ charge bleeds out so you have to top it off again every so often. The way you do that is to just write the same data back again. So it reads and writes the same data to itself every refresh. The opposition to this is static RAM which does not use a capacitor and is just a clever arrangement of transistors. No refresh needed. It’s not typically used commercially except under special requirements, though as transisters are significantly more expensive. So the refresh strategy is the better choice for consumer hardware. DRAM has been dominant for decades.
If you ever have the chance to use an old Apple II computer, run a text mode program, wait til the owner is looking in the other direction and turn the power off and back on quickly.
For about a second, before you hear the loud BOOP and the screen clears, you’ll see whatever was on the screen just before you powered it off. But a few characters will be corrupted. Try it again, and wait a half a second longer than before. More characters will be corrupted.
For that brief second you’re looking at the contents of the video RAM, then the ROM (Apple called what we call BIOS now “ROM”) clears the contents and puts up the familiar text banner. The longer the power stays off, the more the contents of those flash cells decay and flip the bits that determine what character shows up in a location on the screen.
The camera hack is really cool - i love stuff like that.