ZX81 keyboard layout
                                    ====================
              +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
              |     |     |     |     |     |     |     |     |     |     |
              | EDIT|  AND| THEN|   TO|LEFT |DOWN | UP  |RIGHT|GRAPH|RBOUT|
              |  1  |  2  |  3  |  4  |  5  |  6  |  7  |  8  |  9  |  0  |
              +-+---+-+---+-+---+-+---+-+---+-+---+-+---+-+---+-+---+-+---+-+
                |PLOT |UNPLT|REM  |RUN  |RAND |RETRN|IF   |INPUT|POKE |PRINT|
                |  "" |  OR | STEP|  <= |  <> |  >= |  $  |  (  |  )  |  "  |
                |  Q  |  W  |  E  |  R  |  T  |  Y  |  U  |  I  |  O  |  P  |
                | SIN | COS | TAN | INT | RND |STR$ |CHR$ |CODE |PEEK | TAB |
                +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
                   |NEW  |SAVE |DIM  |FOR  |GOTO |GOSUB|LOAD |LIST |LET  |     |
                   | STOP|LPRNT| SLOW| FAST|LLIST|  ** |  -  |  +  |  =  |FUNCN|
                   |  A  |  S  |  D  |  F  |  G  |  H  |  J  |  K  |  L  |NEWLN|
                   |ARSIN|ARCOS|ARTAN| SGN | ABS | SQR | VAL | LEN | USR |     |
              +----+---+-+---+-+---+-+---+-+---+-+---+-+---+-+---+-+---+-+-----+
              |        |COPY |CLEAR|CONT |CLS  |SCRLL|NEXT |PAUSE|     | BREAK |
              |        |  :  |  ;  |  ?  |  /  |  *  |  <  |  >  |  ,  |   £   |
              | SHIFT  |  Z  |  X  |  C  |  V  |  B  |  N  |  M  |  .  | SPACE |
              |        | LN  | EXP | AT  |     |INKY$| NOT | PI  |     |       |
              +--------+-----+-----+-----+-----+-----+-----+-----+-----+-------+