I wonder what the performance would be like, since the TCP is in a user process (a different one from the application), i.e. there's a process switch every time the application goes to send or receive data. This wouldn't have been such an issue when the code was written, since ARPANet-type networks were not very fast, but with a better network, it would have been limiting. There was no 'MIT' network API. He was talking about the CHAOSNet API. The TCP/IP done in the CSR group at MIT used a totally different API. The various Unix systems at MIT were pretty well out of touch with each other, and did not exchange code. The only exceptions were the DSSR (later RTS) and CSR groups in Tech Sq, who used pretty much the same system. Noel