[gelstudios]

Curious, what does someone gain with MacTCP? I'm not familiar with the space, but a casual glance (not an assessment!) suggests that OpenTransport was standard-ish from system 7.6 onwards.

Does it boil down to compatibility with older hardware?

[retrac]

Different software. They had different APIs from the programmer perspective. MacTCP was older and was based on Berkeley sockets (I think with some BSD code in the implementation?) and was somewhat primitive.

OpenTransport was fully multithreaded and based on SysV UNIX streams. Technically much superior. It has partial MacTCP API support for older apps but some programs demanded real MacTCP to work properly. I think Mac was the only place that really used Streams widely. Mac network programming in the OpenTransport days was alien from a Unix perspective.

OS X now uses sockets like everyone does these days.

Going off memory here it has been a long long time.

[jjuran]

At the very least, MacTCP supports System 6 and the 68000; Open Transport is incompatible with both.

(I seem to recall there's a version of OT you can use with System 7 Pro, a.k.a. System 7.1.1.)