Old programmer's bible

I don't have many books on my work shelf. One of them stands out though:

"Programmer's PC Sourcebook", second edition, which I got maybe in early 90s (I don't remember exactly when). I used to call it 'bible', even. It covers mostly MS-DOS and BIOS level stuff, so literally all the information within it is completely useless these days - unless of course you happen to work with ancient computers or emulators (say, dosbox). Which I don't.

I don't think I have even opened it since late 90s when it started to become completely obsolete, but I just don't have heart to throw it away. That single book just has been so very useful to me in the past. Information from time when computers were so much simpler to work with. I'm using the work in 'you can see and know everything happening under the hood' sense, unlike these days where operating systems hide all the cool details from the user - or in worst case, actively prevent users from seeing anything past provided API.

Let's just call is nostalgia. Or maybe part of the reason why I like to work with embedded stuff; I get both to make the hardware and program it. Working with low level stuff is what I like to do most, maybe because that is what I started with so long ago.