Method and apparatus for character code generation

Claim 3

A method as claimed in claim 1 in which a first plural key operation comprises operating a first key (12) whereafter a second key (11) is operated while the first key is still operated, to generate a first character code ("A"), and a second plural key operation comprises operating said second key (11) whereafter said first 'key (12) is operated whilst said second key is still operated, to generate a second character code ("R").

Claim 4

3 . A method as claimed in claim 1 in which two plural key operations comprise depressing a first key (13), depressing a second key (11), releasing said first key, depressing a third key (12), releasing said second key, and depressing a fourth key, the first plural key operation for generating a first character code ("E") being determined by the first and second keys, and the second plural key operation for generating a second character code ("H") being determined by the third and fourth keys.

Claim 5

A method as claimed in claim 1 in which two plural key operations comprise depressing a first key (22), depressing a second key (23), releasing said second key, and re-depressing said second key or a third key (13), the first plural key operation for generating a first character code ("L") being determined by the first and second keys, and the second plural key operation for generating a repeat of the first character code ("L") being also determined by the first and second keys, or for generating a different character code ("P") being determined by the first and third keys.

Claim 9

Apparatus for generating character codes comprising a keyboard (1), character code generating circuitry (4, 8, 10), said keyboard having a plurality of keys and said circuitry being such that a single key operation of any one of said keys can cause said circuitry to generate a respective character code for that key, said circuitry also being such that a plural key operation involving operation of a plurality of said keys in a predetermined sequence causes said circuitry to generate a respective character code for that particular plurality of keys operated in that predetermined sequence, characterised in that the circuitry is designed to distinguish constituent key operations of a plural key operation in a said predetermined sequence from a said single key operation, having regard to a predetermined keyboard operational rule that for a plural key operation, the plurality of keys are operated in the particular sequence until all those keys are simultaneously operated.

Claim 10

Apparatus for generating character codes comprising a keyboard (1), character code generating circuitry (4, 8, 10), said keyboard having a plurality of keys and said circuitry being such that a single key operation of any one of said keys can cause said circuitry to generate a respective character code for that key, said circuitry also being such that a plural key operation involving operation of a plurality of said keys in a predetermined sequence causes said circuitry to generate a respective character code for that particular plurality of keys operated in that predetermined sequence, characterised in that the circuitry is designed to distinguish constituent key operations of a plural key operation in a said predetermined sequence from a said single key operation, having regard to a predetermined keyboard operational rule that for a plural key operation, the plurality of keys are operated in the particular sequence until all those keys are simultaneously operated.

Claim 11

Apparatus as claimed in claim 8 on which said circuitry includes signal means (4;51,54,56) operable to indicate respectively when one key has been operated, and when at least one subsequent different key has been operated while said one key is operated, and when no key is operated, the circuitry distinguishing a single key operation by an indication of one key being operated, followed by an indication that no key is operated, and distinguishing a plural key operation by an indication of one key being operated, followed by an indication of a subsequent different key being operated while said one key is operated.

Claim 12

Apparatus as claimed in claim 8 or 9 in which said circuitry indludes key-code means (51,54,R1,R2) for generating key codes for operated keys of the keyboard, and an addressable store (80) of different character codes, and means responsive to a key code resulting from a single key operation, or to key codes resulting from a plural key operation, to address the store and read out from it the appropriate character code.

Claim 13

Apparatus as claimed in claim 10 in which said key-code means includes keyboard scanning means (4;51, 54,R1) for repeatedly scanning the keyboard for operated keys, and at least one register (R2) for storing the key code of a first operated key while the keyboard scanning means continues to scan the keyboard.

Claim 14

Apparatus as claimed in claim 11 as dependent indirectly on claim 9 in which said keyboard scanning means includes a register (R1) for storing the key code of the key currently to be scanned, and said signal means includes an arithmetic logic unit (54) arranged to compare the content of said registers (R1 and R2), different key codes in the registers indicating that a subsequent different key has been operated while said one key is operated.

Claim 15

Apparatus as claimed in claim 9 including timing means (R3) which prevents the circuitry distinguishing a single key operation unless the indication that no key is operated, follows by more than a predetermined time interval established by the timing means, the indication of one key being operated.

Claim 16

Apparatus as claimed in any of claims 8 to 13 in which the keyboard is a one-hand operated keyboard, and each key (eg. 23) is marked with a number of characters (F,G,X,T,K,6,;=,?), whereby when two keys are to be depressed in a sequence for generating the character code for a specific character (eg.F), the character marking for the specific character (F) on a key defines that this key (23) is the second key to be actuated, and the location of the character marking on the key defines the first key (4) to be depressed.