A lot vs. Alot: 9 Grammatical Pitfalls
Part of earlier versions of MacOS that provided access to TCP/IP services. Apple removed MacTCP from MacOS in revision 7.5.3 in favor of the new OpenTransport (OT) TCP/IP stack. However, MacTCP lives on as a community development effort.
See also MacPPP.
[How did it work? Where was it from?]