Xref: utzoo comp.protocols.misc:1076 comp.os.cpm:4327 alt.folklore.computers:6885 Path: utzoo!attcan!uunet!mcsun!ukc!edcastle!cs.ed.ac.uk!cs.edinburgh.ac.uk!gdmr From: gdmr@cs.edinburgh.ac.uk (George Ross) Newsgroups: comp.protocols.misc,comp.os.cpm,alt.folklore.computers Subject: Re: Early microcomputer networks Message-ID: <1593@skye.cs.ed.ac.uk> Date: 8 Nov 90 11:44:34 GMT References: Sender: nnews@cs.ed.ac.uk Reply-To: gdmr@cs.edinburgh.ac.uk (George Ross) Organization: Department of Computer Science, Edinburgh University Lines: 41 In article , news@helens.Stanford.EDU (news) writes: > ... But what about networks that became extinct, the > network dinosaurs? What was happening with other mini/microcomputer > networks around that time? They're still alive and kicking (at least, in their later incarnations). In the early '70s we had an assortment of minis, tied together with point-to-point "links", running initially at about 256Kbaud, and latterly at 2Mbaud. These links were full-duplex flow-controlled, with error detection (parity and positive/negative acknowledgement). The machines included several Interdata 70s, a dozen or so 74s, a PDP-8, a PDP-9 and a PDP-15. Originally they all ran their usual operating systems, but around 1976 we added a big (67Mbyte!) disc to one of the 70s and converted it to a file server. At first it just did file storage and transfer, but by the early 1980s we had converted the 74s to be discless clients which booted from the central server (thanks to the AUTOLOAD instruction) and then relied completely on it and a separate compute server (another 70). Meantime the PDP-8 had been retired and the 9 and 15 converted to use the central server as a virtual-DECtape server as well as a file server. Since then we've converted the links to a 2Mbaud CSMA/CD network which provides reliable virtual circuits in the firmware, added 60-odd 68K-based machines, retired all the Interdatas and the PDP-9 and 15, and added several new 68K-based file servers. There's nothing left now of the original hardware, though for a while around the mid '80s it was all running happily together. In fact, the last "link" board was removed just last year when we switched off our 780. The file access protocol is still the same, though, more or less, as that used in 1976 -- the only difference is that the current servers don't understand some of the more baroque block-size constructs needed to get the virtual DECtapes working sensibly. It's a stateful protocol, btw, with user validation done by the servers on the basis of link- and VC-specific tokens issued by them in response to the initial logon request. Just what's needed, in fact, to deal with a labful of students all doing operating systems practicals. > > Jim Helman > Department of Applied Physics Durand 012 > Stanford University FAX: (415) 725-3377 > (jim@KAOS.stanford.edu) Work: (415) 723-9127 -- George D M Ross, Department of Computer Science, University of Edinburgh 031-650 5147 or 031-667 1081 gdmr@uk.ac.ed.cs (or cs.ed.ac.uk if you prefer)