Source-level debugger for RR Janus/Ada?

[icsu8209@attila.cs.montana.edu (Glassy)]

Hello, all.  Is there a source-level debugger for Janus/Ada?  Our site
has a license for Janus/Ada; I used it for one short program last year,
but before I throw a lot of code at it, I'd like to get my grubbies
on a source-level debugger.  

Does RR or a third party make a debugger for Janus/Ada?  Alternately,
is there a way I can use some other commercially-available debugger
(say, Borland's Turbo Debugger?) to debug Janus/Ada code?

The debugger-functionality I'm looking for isn't (I think...) all that
extensive; I'd like to be able to step through a program, step into
procedures and functions, examine values of variables, and maybe set or
clear breakpoints...

--oh, yes, and spend less than $100 on it? 
(student budget, strikes again! ;-)

Please email replies, and I'll summarize for the net in a few days...

Thanks in advance,

Lou Glassy (icsu8209@caesar.cs.montana.edu)