I wish the author had included the full ascii chart in 4 bits across / 4 bits down. You can mask a single bit to change case and that is super obvious that way.
The charts that simply show you the assignments in hex and octal obscure the elegance of the design.
I was going to ask you to please explain as I didn't understand, but I am guessing you are talking about the same thing as this comment[1] right? That's super cool
The third and fourth columns of the table are only a single bit apart from each other. If you mentally swap the first two columns, you get a Gray code ordering of the most significant bits, which is pretty close to what you're looking for.
The charts that simply show you the assignments in hex and octal obscure the elegance of the design.