On version 8.0.5 ,SVRMGR is issued by svrmgrl and not by svrmgr30.

See the following example (On Unix):

hp64 23: svrmgrl

Oracle Server Manager Release 3.0.5.0.0 - Production

(c) Copyright 1997, Oracle Corporation. All Rights Reserved.

Oracle8 Enterprise Edition Release 8.0.5.2.1 - Production
PL/SQL Release 8.0.5.2.0 - Production

SVRMGR> connect internal
Connected.

On your NT machine,try fisrst the command:
set oracle_sid = ;
and then : svrmgrl

send us the output of those commands.

Regards,

Nir