In the 1980s, a company called Keypunch Software sold budget software
for the Atari 800 and other personal computers. I want to know who
currently owns Keypunch Software - specifically, who owns the
copyright to those titles.

I know from http://www.infogrames.com/corp_people_paulrinde.php that
Keypunch was founded by Paul Rinde in 1984, and that he sold the
company in 1989. I want to know who he sold the company to, and if
possible, contact information for that person or company.

Keystone software recently was renamed from Keystone Software plc to
Keystone Solutions Group plc. Their new contact info is as follows:

Keystone Software Solutions, Inc. 
529 Reading Avenue Suite M-1, Reading, PA 19611 
(610)685-2111 (800) 289-9109 x11 (toll-free) 

Hope this might be of some assistance. --Brian

Hi waffle,

I managed to track down the original address of Keypunch.

Keypunch Software
1221 Pioneer Building
St. Paul, MN 55101
(612) 292-1490

Interestingly, today that phone number returns the following :

American Luggage & Case Inc, 
106 Fillmore Ave W, 
Saint Paul, 
MN 55107
(612) 292-1940,

The Corporate Information link you show has the most promise. Since
Keypunch Software was in St.Paul MN and Mr. Rinde is now working for
Infogrames in Minneapolis MN, why not just call or email him and ask
him? Tell him you're researching early computer game development for a
book. Keypunch's name appears to totally disappear after 1989. One
source I find says that they went out of business; it implies there
was some money owed programmers. Contact me if you want either of the
links I allude to.