(It would be so very awesome if this was the sort of documentation you got if you purchased a new computer, although perhaps on a disc instead of hardcopy.)
I'm not sure which Zones Of Thought book it was (probably Deepness in the Sky), but my favorite software joke in SciFi is when someone deep-diving into the system discovers that at the deepest layers timekeeping is still calculated from the UNIX epoch on the long lost human homeworld.
"The 16-bit segment selector in the segment register is interpreted as the most significant 16 bits of a linear 20-bit address"
However, Wikipedia has a funny quote on that
"Once the BIOS has found a bootable device it loads the boot sector to linear address 7C00h (usually segment:offset 0000h:7C00h, but some BIOSes erroneously use 07C0h:0000h"
IBM's BIOS put the boot loader at the end of the minimum amount of memory at the time (32KB). 7C00-7DFF get the boot sector, and 7E00-7FFF are scratch space.
Also once upon a time SCP tucked it into 0200-03FF because that ram was otherwise unused.
> "DOS 1.0 required a minimum of 32KB, so we weren't concerned about attempting a boot in 16KB."
> (Note: DOS 1.0 required 16KiB minimum ? or 32KiB ? I couldn't find out which correct. But, at least, in 1981's early BIOS development, they supposed that 32KiB is DOS minimum requirements.)
And today I learn about Terry Davis, TempleOS and showdead. Moderation and censorship is a travesty online. Fortunately showdead allows us to bypass it somewhat.
Soon the community will be able to selectively un-auto-[dead] comments. We've been working on this for a long time. It's currently in alpha testing, and indeed the alpha-testers (not moderators) unkilled https://news.ycombinator.com/item?id=10282575, which is precisely the intent of the feature.
You can see the actual bootloader code in the PC's BIOS here:
http://static.pcjs.org/pubs/pc/reference/ibm/5150/techref/19...
The address is mentioned in lines 44 and 45 here:
http://static.pcjs.org/pubs/pc/reference/ibm/5150/techref/19...
(It would be so very awesome if this was the sort of documentation you got if you purchased a new computer, although perhaps on a disc instead of hardcopy.)