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Since the 70s,
different committees of the Department of Electronics
and the Department of Official Language have been
evolving different codes and keyboards which could cater
to all the Indian scripts due to their common
phonetic structure. Earlier efforts could not keep
the ASCII code intact. The BIS standards IS
13194:1991 conforms to the earlier standard
IS 10402:1982, "8-bit coded character
set for information interchange". It
is intended for use in all computer & communication
media which allow usage of
7 or 8 bit characters. In an 8-bit
environment, the lower 128 characters are
the same as defined IS 10315:1982, "7-bit
coded character set for information interchange"
also known as ASCII character set. The top
128 characters cater to all the ten Indian scripts based
on the ancient Brahmi script. In a 7-bit
environment the control code SI can be used for
invocation of ISCII code set, the control code SO can
be used for reselection of the ASCII code set.
The common
INSCRIPT keyboard overlay allows typing of
all the ten Indian scripts. This
overlays fits on any existing English
keyboard. Alternating between the English and
Inscript overlay is achieved through the CAPSLOCK key.
The INSCRIPT keyboard, provides a logical
and intuitive arrangement of vowels and consonants.
It is based both on the phonetic properties
and the relative usage frequencies of the
letters. Not only does this made the
keyboard much easier to learn, but also enables
a person to type subsequently in all the Indian
scripts.
The ISCII
code table is a super-set of all the characters
required in the ten Brahmi-based Indian
scripts. An optimal keyboard overlay
for these scripts is made possible
by the phonetic nature of the alphabet. The
differences between scripts primarily are in their written
forms, where different combination rules get used.
There are manifold
advantages in having a common code and keyboard
for all the Indian scripts. Any software which
allows ISCII codes to be used,
can be used in any Indian script,
enhancing its commercial viability.
Furthermore, immediate transliteration
between different Indian
scripts becomes possible, just by changing
the display modes.
The 8-bit
ISCII code retains the standard ASCII code, while
the Indian script keyboard overlay is designed for
the standard English can co-exist with
Indian scripts. This approach also makes
it feasible to use Indian scripts along
with existing English computers and software, so
long as 8-bit character codes are allowed.
The ISCII code
(Indian Script Code for
Information Interchange, co-exists with the standard
English code: It contains only
the basic alphabet arranged in an order
which conforms to that in most of the Indian dictionaries.
As the display
rendering depends entirely on the composition methodology,
it is possible to view the same text in different
styles prevalent in the script. It is possible
to transliterate the text to Roman script, using
additional signs oon the letters (diacritic
marks), for removing ambiguities. It
is even possible to have the initial letters
capitalised in the Romann text.
ISCLAP is a
two byte code, which can be used within 7-bit (such as
POCSAG, FLEX) as well as 8-bit (such as RDS) Paging
environments. ISCII code (Indian Script Code for Iformation Interchange)
standardised by Bureau of Indian
Standards (IS 13194:1991) defines a
superset of alphabet required for Indian
scripts. These alphabet codes,
require some context-sensitive pre-processing
before they can be displayed or printed. The
Pager industry, however, felt a need for a simpler
code, for display- only applications
as in pagers. Most of the microcontrollers
used within Pagers may not have the processing power or
the code- space for handling ISCII code, while
they can use a separate Character-Generator
ROM which can store thousands of characters, as
needed for Chinese. Like the Chinese
character set, the ISCLAP character
set has a few thousand characters for
each Indian Script, these however can be just
placed one after the other in
the manner of English characters. Unlike
the ISCII code, ISCLAP code does not have any context-sensitivity,
but can still render almost all the combinations
of ISCII characters used in the modern scripts.
The ISCLAP code
was evolved in April 1996 by Telecom Engineering Centre(DOT)
in association with Department of Electronics, AIR R&D,
National Informatics Centre and Bureau of Indian Standards.
Brahmi based Indian scripts .India has two families of
scripts - one based on the ancient Brahmi script, and
the other on the Perso-Arabic script. The Brahmi script
(400 BC) had a phonetic alphabet. The consonants had implicit
`a' vowel. Vowel-signs had to be attached on them to indicate
a different vowel. Consonants without the intervening
`a' vowel were depicted by combining the I shapes. Brahmi
also had an `Anuswar' sign to indicate nationalisation.
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