sql plus login problem with password prompt

I can login to my Oracle servers just fine if I supply my name/password and service name. But if I want SQLPlus to prompt for my password, the login fails. Will some helpful, knowledgeable person please clue me in on why this happens?

Thank you!
Mac
(private email ok, remove the NOTHX)

• Supporting documentation ==

SQLPLUS session:

SQL> conn joee/joee_at_bdev
Connected.
SQL> disc
Disconnected from Oracle8 Release 8.0.4.0.0 - Production PL/SQL Release 8.0.4.0.0 - Production
SQL> conn joee_at_bdev
Enter password: ****
ERROR:
ORA-12154: TNS:could not resolve service name

C:\ORANT\NET80\ADMIN\SQLNET.ORA: (The only file of this name on my PC)

AUTOMATIC_IPC = OFF
TRACE_LEVEL_CLIENT = OFF
names.directory_path = (TNSNAMES, HOSTNAME) names.default_domain = world
name.default_zone = world
sqlnet.authentication_services = (NTS)

C:\ORANT\NET80\ADMIN\TNSNAMES.ORA: (The only file of this name on my PC)

<snip>

BDEV.WORLD =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = bhost_db)(PORT = 1521))     (CONNECT_DATA = (SID = orcl))
  )
<snip>

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