[TUHS] More Spider

I noted with much pleasure that the main bitsavers site is back up, and that at some point it has added a full set of scans of “Datamation”. The Feb 1975 issue contains an article from Dr. Fraser about Spider and the network setup in Murray Hill early in 1975: http://bitsavers.org/pdf/datamation/197502.pdf For ease of reference I have also temporarily put the relevant 4 pages of the issue here: https://gitlab.com/pnru/spider/blob/master/spider.pdf I find the graphic that shows how Spider connected machines and departments the most interesting, as it helps understand how the pro’s and con’s of Arpa Unix might have been perceived at that time. The more I read, the more confused I become whether the “Pierce loop” was a precursor to “Spider” or a parallel effort. The facts appear to be that John Pierce (https://en.wikipedia.org/wiki/John_R._Pierce) submitted his paper to BSTJ in December 1970, essentially describing a loop network with fixed size short datagrams, suggesting T1 frames. It is quite generic. In February 1971 W.J. Kropfl submits a paper that describes an implementation of the ideas in the Pierce paper with actual line protocols and a TIU. In October 1971 C.H. Coker describes in a 3rd paper how to interact with this TIU from a H516 programming perspective. Several Spider papers mention that the project was started in 1969 and that the first Spider link was operational in 1972. The team appears to be entirely different: the h/w is credited to Condon and Weller, and the s/w to Frazer, Jensen and Plaugher. The Spider TIU is much more complex (200 TTL chips vs. 50 in the Kropfl TIU). The main reason for that - at first glance - appears to be that in the Spider network the TIU handled guaranteed in order delivery (i.e managed time outs and retransmissions), whereas in the Kropfl implementation this was left to the hosts. It would seem logical that the latter was an evolution of the former, having been developed at the same site at the same time. A 1981 book seems to take that view as well: “Local Computer Network Technologies” by Carl Tropper includes the text "Spider Spider is an experimental data communications network which was built at the Bell Telephone Laboratories (Murray Hill, New Jersey) under the direction of A. G. Fraser. A detailed description of the network is given by Fraser [FRAS74]. This network was built with the notion of investigating Pierce's idea of ...” The chapter is titled “The Pierce loop and its derivatives”. This is a much as Google will give me - if somebody has the book please let me know. On the other hand, the Spider papers do not mention the Kropfl network or Pierce’s paper at all. The graphic in Datamation appears to show two Kropfl loops as part of the network setup. Yet, this is described in the accompanying text as "4. Honeywell 5l6: Supports research into comunications techniques and systems. The machine has a serial loop I/O bus threaded through several labs at Murray Hill. Equipment under test is connected either directly to the bus or to a minicomputer which is then connected to the bus. Also avail- able are graphics display terminals and a device that can write read-only memory chips.” Maybe this is a different bus, but if it is the same as the Kropfl loop, to call it a “serial loop I/O bus” suggests it was a parallel effort unrelated to Spider. Does anybody on the list recall whether Spider was a parallel effort or a continuation of the earlier work?