The First Internet Computers In Texas

Thanks to Clive Dawson's excellent discussion, it's now known that the first Internet computers in Texas were on campus at UT Austin from 1977. There was an initial PDP-11, followed soon after by UTEXAS-20 a PDP-10 based DEC-20 and UTEXAS-11 a second PDP-11. And actually of course, what truly came first was an ARPANET IMP, the essential gateway into the ARPANET. In UT's case, there was an initial IMP with the initial PDP-11, followed soon after by a second IMP in the old Computation Center machine room. Like modern network routers, an IMP's only purpose was to interact with the network. Unlink modern routers, IMPs came in heavy steel cabinets and were centrally managed from the BBN network control center in Boston. While it's true that UT was already at the center of an important regional network, the first ARPANET machines on campus were historic. [1][2]

Thanks to the work of Lars Brinkhoff the IMPs have come back to life and it's possible to reconstruct core parts of the original UT Austin environment, in other words, the dawn of the Internet in Texas. The question then becomes, is it also possible to reconstruct the original PDP-11s and DEC-20? There things become complicated. The short answer is that it may be possible for the DEC-20 because it was in some sense a regular, normal ARPANET machine with full support from DEC, in particular the TOPS-20AN operating system and AN20 interface hardware. These were regular commercial products with fairly good records and archival material still available today.

Before diving into the topic of the DEC-20, what about the PDP-11s? The key question seems to be the NCP Network Control Program software. This is essentially software driving the networking hardware connecting a machine to an IMP, and the issue here is that the PDP-11s were running adhoc custom UNIX operating systems (from the University of Illinois?) and it seems very unlikely that the software can be reconstructed now. In a nutshell, the PDP-11s were custom oddities and there's not much hope of restoring them. What's possible is that at some point in the future Lars and others will come up with realistic-enough placeholder software to run on PDP-11s. Old bits, as Lars says, but realistic-enough rather than what it was really like originally.

For UTEXAS-20, there's hope of approaching quite closely to what things were really like originally. A DEC-20 running the special ARPANET ready TOPS-20AN, with the AN20 networking hardware connected to a UT IMP emulator, probably the IMP in the old CC. The first trick will be to reconstruct the TOPS-20AN software, hopefully as an install tape that others can use for their own DEC-20 reconstructions. Then the hardware emulation within Rich Cornwell's PDP-10 code can be tackled. With software and hardware reconstructed for UTEXAS-20, eventually packets could again flow to a UT IMP. Ideally both UTEXAS-20 and the IMP will live side-by-side, each in its own independent Docker Container, easily deployed to the cloud, along with a third Container for the HRC DEC-10 running DECWAR. And the reconstructed 1982 UT environment will live on into an unlimited future.

[1] In 1969 the Southwest Region Educational Computer Network was created around the UTCC infrastructure with the help of a grant from the National Science Foundation. By 1972 the network consisted of eleven four-year colleges and universities and three secondary schools across Texas. UTCC staff and the computer science faculty provided the core resources for the network. The establishment of the network was a pioneering step in regional academic collaboration that cemented UT Austin’s status as the regional hub for computing and served as a precursor to modern distributed computing networks and the Internet. Of the fourteen institutions in the network, only UT Austin, Rice and Trinity universities had sizable computing facilities and well-established computing programs on campus. Note that both Austin High and McCallum High were network members.

[2] The first IMP was installed at UT Austin in 1977, with a second arriving within the next few years. By the March 1977 ARPANET map, Texas is clearly visible as a node, and the ARPANET Directory from 1978 lists the University of Texas at Austin (specifically the Linguistics Research Center and Computation Center) as a fully operational host. In the transition to the modern Internet in the eighties, UT Austin was assigned significant network resources. Notably, the Class A network 39.0.0.0 was assigned to the UT Austin BRC (Balcones Research Center) in later IP registries.

DEC's description of the ARPANET ready TOPS-20AN.

ARPANET IMP

ARPANET NCC network control center at BBN in Boston