The Inscript Keyboard:
The Inscript (Indian Script) keyboard overlay was standardized by DoE in 1986. ("Report of the Committee for Standardization of Keyboard Layout for Indian Script Based Computers", Elec- tronics-Information & Planning Journal, Voi. 14, No.1 October 1986).
A revision was done in 1988 by a DOE committee, when it was decided to compact the ISCII code by deriving some characters using a separate Nukta character. This required substitution of the Nukta character in place of the earlier "Transform" key. From frequency considerations it became necessary to mutu- ally adjust the positions of vowels, along with their Matras.
The Inscript overlay can be used on any QWERTY keyboard. The Indian script legends should be shown in the right-hand side of a key, as the left hand side has the English legends.
Temporary selection of the other overlay can be achieved by pressing the key along with the RIGHT ALT key (In IBM En- hanced keyboard), or the SYS-REQ key (In PC-AT 88-key keyboard). This can be very convenient for embedding a single character from the other overlay.
The Inscript overlay contains characters required for all the Indian scripts, as defined bv the ISCII character set. The Indian script alphabet has a logical structure, derived from the phonetic properties. The Inscript overlay mirrors this logical structure. The overlay has also been optimized from phonetic/ frequency considerations. It is divided into two parts: the vowel pad on the left hand side, and the consonant pad on the right hand side.
Within the vowel pad the vowels are given in the shift positions of the corresponding Matras. All the five main short vowels are given in the home row while their longer counterparts are located on the corresponding keys just above them. Since the vowel does not have a corresponding Matra, the vowel- omission sign, Halant, is given in the unshifted position. Halant is used for forming conjuncts, when it is typed in between con-sonants.
Alternate hand action gets used in typing of a conjunct; as Halant is typed from the left pad, while most of the consonants are typed from the right pad. Similarly alternate hand action occurs while typing a Matra after most of the consonants. This considerably speeds up typing of a syllable.
In the consonant pad all the primary characters of the 5 Vargs are included in the home row. The aspirated consonants are kept in the shift positions of their unaspirated counterparts. The non-nasal consonants of each Varg are contained in a pair of vertically adjacent keys.
The main nasal consonants of the Vargs are contained in the bottom row of the left pad, along with the related Anuswar and Chandrabindu. The other non-Varg consonants are kept in the remaining positions of the right pad, according to their logical relations, and usage frequencies.
All the characters needed for touch typing are contained in the bottom 3 rows. The top row contains some conjuncts meant for ease in sight typing. The conjunct character keys actually send out the corresponding basic characters.
Due to the phonetic/alphabetic nature of the keyboard, a person who knows typing in one Indian script can type in any other Indian script. The logical structure allows ease in learning, while the frequency considerations allow speed in touch typing. The keyboard remains optimal both from touch-typing and sight-typing points of view, in all Indian scripts.