case sensitive/insensitive confusion

I am seeing different ORDER BY results
on a character column on different machines.
I have (1)
ResyDBE=# select version();
version
------------------------------------------------------------------------
PostgreSQL 7.4.5 on hppa-hp-hpux10.20, compiled by GCC gcc (GCC) 3.3.1

ResyDBE=# \l ResyDBE
List of databases
Name | Owner | Encoding
-----------+-------+-----------
ResyDBE | rodos | SQL_ASCII

ResyDBE=# select parameter_name from parameter_define where
parameter_name ilike 'c%' order by 1 limit 8;
parameter_name
----------------
CAENAM
CAENAM
CAENAM
CBERRY
CBERRY
CCCTOG
CCCTOG
CCCTOG

and (2)
ResyDBE=# select version();

version
-------------------------------------------------------------------------------------
PostgreSQL 7.4.5 on i686-pc-linux-gnu, compiled by GCC gcc (GCC) 3.3.1
(SuSE Linux)

ResyDBE=# \l
List of databases
Name | Owner | Encoding
-----------+-------+-----------
ResyDBE | rodos | SQL_ASCII

ResyDBE=# select parameter_name from parameter_define where
parameter_name ilike 'c%' order by 1 limit 8;
parameter_name
----------------
c12a
c12b
c12c
c1a
CAENAM
CAENAM
CAENAM
CAENAM

It seems to me under hpux the sort is done case sensitive,
as would one expect on SQL_ASCII encoding, whereas
under linux a case insensitive sort is done.
I'd like to see the hpux behaviour under linux too.
Has anybody seen something like this?
TIA

Regards, Christoph