ASCII - American Standard Code for Information Interchange. (1963,1967,1986)
  IBM supported its use, it was not quite ready when they released the 360 
    architecture.

  7-bit - compatible with punch tape and AT&T teletype hardware.
    
  Did away with shift set of alternative characters.

  128 value possible.
     Represents 0-9, A-Z, a-z, punctuation, and device control.
       Some punctuation appears between the sequences 0-9, A-Z, and a-z.
       But within each sequence, values are sequential and contiguous
         J (74) does follow I (73) 
         making collation much easier to code.

     33 non-printable control characters for controlling output devices.
       - teletype and later printers

       Print control. 
         Backspace, linefeed (vt), form feed, tab (ht), carriage return (cr),
         linefeed (lf), etc. 
         # interpreted by device.
       
       Transmission control.
         CTS (clear to send), RTS (ready to send), EOT (end of text), etc.

       DOS/Windows systems use [cr][lf] (13,10) character pair to mark end
         of current line.
    
       Unix/Linux systems use only [lf] (10).

       Early Apples and other used only [cr] (13).

       Early printers handled [cr] and [lf] separately allowing over-strike 
         (reprint over same line) or other formatting such as stair-case
         indenting.

     94 printable A-Z,a-z,0-9 and various punctuation.
      1 space - invisible graphic (actual value - not null)
 
    Image of character (glyph) defined by device displaying.

    00 - null (nul) ~ neither printable or non-printable, control character(?)
      Sometimes refereed to as the null terminator.
    In C, marks end of string.
    Sometimes represents a NOP as a way to stall while some other action 
      completes.

  High bit usage (in 8 bit byte storage).
    For ASCII, set to null
      
    Some systems use as parity check.
      
    A number of system and equipment makers used high bit to define an
      additional custom character set.

      Some non-English western languages characters. (for French, Spanish, etc.)

      Simple graphic symbols - often custom to system or device (Epson vs. IBM)
        Smiley faces, lines and angles used to draw boxes on screen.
        IBM code page 437
        

  Still geared for English/Western European character sets

Code pages
  see wikipedia topic ISO_8859-1

  Before Unicode, computer manufacturers used OEM code pages to define
    alternative character sets for other languages.

    Code pages were firmware re-definitions of the 7-bit ASCII and, possibly,
    the hi-bit extension values to reflect the characters of a specific 
    country.    

    e.g computers sold to Russia displayed Cyrillic characters.
     (and only Cyrillic)

    Eventually, these were standardized - ANSI/ISO 8859 code pages
      But still based on 1 bytes characters.
 
    * IBM and Microsoft keep separate 'standards'.

    See 'code pages' on wikipedia.

    Re-introduces the problem of converting information between systems
      using different definitions of character sets.