ASCII Bits
🡸 lup:7-bit ASCII is generally organized over sections of 32 (+0x00 - +0x1F), or, in other words, the bottom 5 bits (000X XXXX).
the topmost bit isn’t used.
the next top 3 bits determine either symbols or modifier keys:
000X XXXX | ctrl-modifier
001X XXXX | symbols (special case)
010X XXXX | shift-modifier (uppercase)
011X XXXX | no modifiers (lowercase)
the 32 symbol entries are divided into two 16 intervals, with the top 5th bit being a shift modifier:
0010 XXXX | no modifier
0011 XXXX | shift-modifier
the symbols don’t line up perfectly with US standard keyboard.
historically (typewriters and teletypes) was a different story.