Newsgroup: soc.culture.greek


Article 3493 of soc.culture.greek:
Path: icdoc!dds
From: dds@doc.ic.ac.uk (Diomidis Spinellis)
Newsgroups: soc.culture.greek
Subject: Re: Keyboards in Greece
Summary: Encoding for Greek characters on PC machines
Message-ID: <3008@gould.doc.ic.ac.uk>
Date: 13 Mar 91 11:06:36 GMT
References: <4102@dciem.dciem.dnd.ca> <1264@theseas.ntua.gr>
Sender: news@doc.ic.ac.uk
Organization: Dept. of Computing, Imperial College, London, England
Lines: 46
Content-Length: 2533
In article <1264@theseas.ntua.gr> zvr@ntua.gr writes:
[...]
>    The PC compatibles usually don't use the ELOT standard, either
>(although there are versions that do).  They use a particular encoding
>called IBM-422 (if I remember correctly), which apart from the fact
>that uses a different encoding, lacks the characters produced
>by three-key sequences (iota with accent and diaeresis, for example).

There are actually three character encodings used on PC compatibles today:

The most widespread is the one called "437" (the number is supposed to be
the code page number).  This is a de facto standard from the early days
of the Greek costumisation efforts probably defined by Memotek S.A. who
did one of the first Greek costumisations for PCs.  Greek characters
start at code 128 with capital A and continue onwards occupying the
special characters with umlaut accent etc.  Note that the code page
number 437 is probably misleading as it is supposed to be the US code
page.  I believe that this number is given to the code page because
it is hacked into the US drivers.

When the IBM PS/2 machines appeared IBM put forward another standard
way of encoding Greek characters this time with its own code page
number "851".  I think it is the same encoding as the one used on the
IBM mainframe machines (at least this was the explanation given for the
change).  This leaves many of the special European characters
unaffected but has some Greek characters occupy graphic symbols.
Furthermore there are some gaps between the characters.  The software
to use this encoding is given by IBM in the form of a "National
Language Supplement" disk and manual.

Finally with the appearance of the Microsft Windows 3.00 software which
internally uses the ANSI/ISO 8 bit encoding it became easy to switch
encoding once again and use the ELOT 928 standard.  There are currently
three firms selling Greek adaptations for Windows.  Having done
implementation work for one of them I can say that it uses internally
the ELOT 928 standard.  Special translation tables allow the
transparent cutting and pasting between DOS applications that use the
437 encoding and Windows applications that use the ELOT 928 encoding.

Hope this clears things up a bit.

Diomidis
-- 
Diomidis Spinellis                  Internet:                 dds@doc.ic.ac.uk
Department of Computing             UUCP:                    ...!ukc!icdoc!dds
Imperial College, London SW7        #define O(b,f,u,s,c,a)b(){int o=f(); ...




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