Turing complete Updated 2025-07-16
A computer model that is as powerful as the most powerful computer model we have: Turing machine!
Ciro Santilli can accept closed source on server products more easily than offline, because the servers have to be paid for somehow (by stealing your private data).
Linear polynomial Updated 2025-07-16
A polynomial of degree 1, i.e. of form .
As of 2020, no one knows how to build the major desktop distros fully from source into the ISO, and especially so in a reproducible build way. Everything is done in build servers somewhere with complicated layers of prebuilds. It's crap.
Non-relativistic quantum mechanics Updated 2025-07-16
The first quantum mechanics theories developed.
Their most popular formulation has been the Schrödinger equation.
NoSQL Updated 2025-07-16
x86 Paging Tutorial / PAE Updated 2025-07-16
Physical address extension.
With 32 bits, only 4GB RAM can be addressed.
This started becoming a limitation for large servers, so Intel introduced the PAE mechanism to Pentium Pro.
To relieve the problem, Intel added 4 new address lines, so that 64GB could be addressed.
Page table structure is also altered if PAE is on. The exact way in which it is altered depends on weather PSE is on or off.
PAE is turned on and off via the PAE bit of cr4.
Even if the total addressable memory is 64GB, individual process are still only able to use up to 4GB. The OS can however put different processes on different 4GB chunks.
Why are pages 4 KiB anyways?
There is a trade-off between memory wasted in:
  • page tables
  • extra padding memory within pages
This can be seen with the extreme cases:
  • if the page size were 1 byte:
    • granularity would be great, and the OS would never have to allocate unneeded padding memory
    • but the page table would have 2^32 entries, and take up the entire memory!
  • if the page size were 4 GiB:
    • we would need to swap 4 GiB to disk every time a new process becomes active
    • the page size would be a single entry, so it would take almost no memory at all
x86 designers have found that 4 KiB pages are a good middle ground.
History of the World Wide Web Updated 2025-07-16
Video 1.
Why web tech is like this by Steve Sanderson (2022)
Source.
Neon Updated 2025-07-16

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