Editing Open Transport (section)

===STREAMS===
Prior to the release of Open Transport, the [[classic Mac OS]] used a variety of stand-alone [[INIT (Mac OS)|INITs]] to provide networking functionality. The only one that was widely used throughout the OS was the [[AppleTalk]] system. Among the other [[protocol stack]]s supported, [[MacTCP]] was becoming increasingly important as the [[Internet]] boom started to gain momentum. MacTCP emulated the [[Berkeley sockets]] system, widely used among  [[Unix-like]] operating systems.

MacTCP and the previous generation AppleTalk library were slow on PowerPC-based Macintoshes because they were written for previous generation 680x0-based Macintoshes and therefore ran under emulation on PowerPC-based machines. MacTCP was also lacking in features, however, and a major upgrade was clearly needed if Apple was to keep its hand in the Internet market.

Through the late 1980s several major efforts to re-combine the many Unix derivatives into a single system were underway, and the most significant among these was the [[AT&T Corporation|AT&T]]-led [[System V]]. System V included an entirely new networking stack, [[STREAMS]], replacing the existing Berkeley sockets system. STREAMS had a number of advantages over sockets, including the ability to support multiple networking stacks at the same time, the ability to plug in modules into the middle of existing stacks to provide simple mechanisms for filtering and similar duties, while offering a single [[application programming interface]] to the user programs. At the time it appeared STREAMS would become the ''de facto'' standard.

This change in the market led Apple to move to support STREAMS as well. It also presented two practical advantages to the company; STREAMS' multiprotocol support would allow them to support both TCP/IP and AppleTalk from a single interface, and a portable cross-platform version of STREAMS was available for purchase commercially, one that included a high-quality TCP implementation. Using STREAMS also appeared to offer a way to "one up" [[Microsoft]], whose own TCP/IP networking system, [[Winsock]], was based on the apparently soon-to-be-obsolete sockets.