BBC Master Keyboard Table
                                         =========================

              +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+     +-----+     +-----+      +-----+-----+-----+-----+
ctrl          | &A0 | &A1 | &A2 | &A3 | &A4 | &A5 | &A6 | &A7 | &A8 | &A9 |     |     |     | &AE |      | &AB | &AD | &AF | &AA |
shft          | &90 | &91 | &92 | &93 | &94 | &95 | &96 | &97 | &98 | &99 |     |     |     | &9E |      | &AB | &AD | &AF | &AA |
norm          | &80 | &81 | &82 | &83 | &84 | &85 | &86 | &87 | &88 | &89 |     |BREAK|     | &8E |      | &AB | &AD | &AF | &AA |
     +-----+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+   +-----+-----+-----+-----+
ctrl | &1B |  1  |  2  |  3  |  4  |  5  |  6  |  7  |  8  |  9  |  0  |  -  | &1E | &1C | &AC | &AD |   | &B7 | &B8 | &B9 | &A3 |
shft | &1B |  !  |  "  |  #  |  $  |  %  |  &  |  '  |  (  |  )  |  0  |  =  |  ~  |  |  | &9C | &9D |   | &B7 | &B8 | &B9 | &A3 |
norm | &1B |  1  |  2  |  3  |  4  |  5  |  6  |  7  |  8  |  9  |  0  |  -  |  ^  |  \  | &8C | &8D |   | &B7 | &B8 | &B9 | &A3 |
     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+   +-----+-----+-----+-----+
ctrl    |     | &11 | &17 | &05 | &12 | &14 | &19 | &15 | &09 | &0F | &10 | &00 | &1B | &1F | &AE |      | &B4 | &B5 | &B6 | &FF |
shft    |     |  Q  |  W  |  E  |  R  |  T  |  Y  |  U  |  I  |  O  |  P  |  @  |  [  |  £  | &9E |      | &B4 | &B5 | &B6 | &FF |
norm    | TAB |  q  |  w  |  e  |  r  |  t  |  y  |  u  |  i  |  o  |  p  |  @  |  [  |  _  | &8E |      | &B4 | &B5 | &B6 | &FF |
        ++----++----++----++----++----++----++----++----++----++----++----++----++----++----+-----++     +-----+-----+-----+-----+
ctrl     |     | &01 | &13 | &04 | &06 | &07 | &08 | &0A | &0B | &0C |  ;  |  :  | &1D |    &0D    |     | &B1 | &B2 | &B3 | &AC |
shft     |     |  A  |  S  |  D  |  F  |  G  |  H  |  J  |  K  |  L  |  +  |  *  |  }  |    &0D    |     | &B1 | &B2 | &B3 | &AC |
norm     | CTRL|  a  |  s  |  d  |  f  |  g  |  h  |  j  |  k  |  l  |  ;  |  :  |  ]  |    &0D    |     | &B1 | &B2 | &B3 | &AC |
         +-----+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-----++-----+----+     +-----+-----+-----+-----+
ctrl     |        | &1A | &18 | &03 | &16 | &02 | &0E | &0D |  ,  |  .  |  /  |         | &7F |          | &B0 | &AE |    &9D    |
shft     |        |  Z  |  X  |  C  |  V  |  B  |  N  |  M  |  <  |  >  |  ?  |         | &7F |          | &B0 | &AE |    &9D    |
norm     |  SHIFT |  z  |  x  |  c  |  v  |  b  |  n  |  m  |  ,  |  .  |  /  |  SHIFT  | &7F |          | &B0 | &AE |    &9D    |
         +--------+-----+--+--+-----+-----+-----+-----+-----+-----+-----+--+--+---------+-----+          +-----+-----+-----------+
                           |                                               |
                           |                      &20                      |                             Keypad &90-&FF translated
                           +-----------------------------------------------+                                 via keypad offset


      Low-level keyboard codes before being translated by Shift, Ctrl, Caps.

+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
|  | x0 | x1 | x2 | x3 | x4 | x5 | x6 | x7 | x8 | x9 | xA | xB | xC | xD | xE | xF |
+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
|0x|TAB |    |    |    |    |    |    |    |    |    |    |    |    |RETN|    |    |
+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
|1x|    |    |    |    |    |    |    |    |    |    |    |ESC |    |    |    |    |
+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
|2x|SPC |    |    |    |    |    |    |    |    |    |    |    | ,  | -  | .  | /  |
+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
|3x| 0  | 1  | 2  | 3  | 4  | 5  | 6  | 7  | 8  | 9  | :  | ;  |    |    |    |    |
+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
|4x|    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
|5x|    |    |    |    |    |    |    |    |    |    |    | [  | \  | ]  | ^  | _  |
+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
|6x|    | a  | b  | c  | d  | e  | f  | g  | h  | i  | j  | k  | l  | m  | n  | o  |
+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
|7x| p  | q  | r  | s  | t  | u  | v  | w  | x  | y  | z  |    |    |    |    |DEL |
+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
|8x| f0 | f1 | f2 | f3 | f4 | f5 | f6 | f7 | f8 | f9 |    |Copy| <- | -> |Down| Up |
+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
|9x|    |    |    |    |    |    |    |    |    |    |    |    |    |KRet|    |    |
+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
|Ax|    |    |    | K# |    |    |    |    |    |    | K* | K+ | K, | K- | K. | K/ |
+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
|Bx| K0 | K1 | K2 | K3 | K4 | K5 | K6 | K7 | K8 | K9 |    |    |    |    |    |    |
+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
|Cx|    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
|Dx|    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
|Ex|    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
|Fx|    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |KDel|
+--+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+

 &00     translated to the current TAB character code
 &01     toggles Caps Lock status (Compact: Extend key)
 &02     toggles Shift Lock status
 &90-&9F is added to keypad offset minus &C0 (ie &9D defaults to &0D)
 &A0+    is added to keypad offset minus &B0 (ie &B0 defaults to '0')

On the Master Compact, Ctrl-Shift-BLOCK sets bit 7 on the next keypress and inserts
NULL,key in the keyboard buffer, unless cancelled by the Escape key.