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.