I've been using the HxD hex editor by Mael Horz and recently learned about its ability to display the contents of my entire hard drive(about 1 terabyte). My assumption is that all this data retrieved from the hard drive must be kept in RAM first, and then it can be displayed onto the screen. Since my RAM is only 4 gigabytes, I am confused as to how my 1 terabyte of hard drive contents can be outputted to my monitor screen. My guess is that not all is outputted at once because there is a scroll bar to scroll down the list, but still the contents are displayed extremely quickly.
So what i'd like to know is, does data(the exact binary) need to be kept in RAM in order to be displayed onto the screen?