[Info-vax] 8-bit characters

[Michael Moroney]

On 11/11/2021 3:10 AM, Phillip Helbig (undress to reply) wrote:
> In article <smicj8$h9r$1 at gioia.aioe.org>, Michael Moroney
> <moroney at world.std.spaamtrap.com> writes:
> 
>>>>> notice that COMPOSE-T-H and COMPOSE-t-h create upper and lower case
>>>>> thorn (Þ þ if those characters get through).  If entered by both
>>>>> create the character, unless it is at the beginning of a line, in which
>>>>> case one sees <XDE> or <XFE> (one character, displayed as several).
>>>>> ASCII values are 222 and 254.  Refreshing the screen also causes the
>>>>> mnenonics to appear.  Also, they are not displayed via HELP FORTRAN
>>>>> CHAR DEC.
>>>>>
>>>>> Any deeper reason or just flaky instrumentation?
>>>>>
>>>>> I also notice that × (COMPOSE-x-x) works fine in a DECterm but not on a
>>>>> real VT220 (where most or all other composed characters work).  Again,
>>>>> deeper meaning or just flaky?
>>>>
>>>> You're definitely not looking at ASCII, and AFAIK Þ and þ aren't
>>>> in DEC
>>>> MCS,
>>>
>>> At least HELP FORTRAN CHAR DEC doesn't show them.
>>>
>>>> which likely means you're looking at inconsistent handling of or
>>>> inconsistent configuration of ISO 8859-1 among your apps and OS and
>>>> hardware; I'd guess some here is MCS, and some 8859-1.
>>>
>>> Only LK411, Alpha hardware and DECterm (under CDE, but that's probably
>>> irrelevant).  Maybe they are inconsistent.  :-|
>>>
>>>> You've asked variations of this question over the years too, usually
>>>> involving trying to use EDT past ASCII or maybe past DEC MCS.
>>>
>>> Yes.  :-)
>>>
>> The character set ISO-8859-1 is almost the same as DEC-MCS with some of
>> the undefined DEC-MCS characters being defined in ISO-8859-1.  The
>> exceptions are a few rarely used characters such as Œ and Ÿ.
>> Specifically, ISO-8859-1 has Icelandic Þ and þ, these positions are
>> undefined in DEC-MCS. 99% of the time one can use ISO-8859-1 instead of
>> DEC-MCS and get away with it.
> 
> Right.  And ISO-8859-15 is also similar.  I routinely write € in EDT to
> get the Euro sign when most people read that text.
> 
>> There is an EDT patch which makes it more ISO-8859-1 friendly, actually
>> prompted by a customer who used EDT for strictly ASCII except for a
>> character at the 'þ' position (but not þ).
> 
> So the patch causes the wanted characters to be displayed?  Of course,
> one can enter any value in EDT.

Yes since all characters in the range xA0-xFF are defined and printable. 
In theory it's compatible with any ISO-8859-x character set since EDT 
doesn't care what the actual 8 bit characters are. It's up to the user 
and their program to interpret things correctly.
> 
>> EDT fans may want the patch
>> for its ability to understand terminals with more than 24 lines.
> 
> Will the patch become standard?  Not that I need a terminal with more
> than 24 lines.  :-)
> 
It's a regular patch for VSI V8.4-2x and is already part of 9.X.