How to allow remote direct serial PPP connections

Hello,

I have an old non-Windows machine that needs access to the internet.
It knows how to connect using PPP and SLIP using a direct serial
cable. Can a Windows system accept such a connection (presumably
with RAS) and allow the remote system access to my network
connection?

The problem I'm having with my windows systems is that none
of the COM Ports are available to use to accept connections.
Only LPT1 appears in the drop down list. Naturally my old
system doesn't know how to use an LPT connection for
IP.

Thank you,

David