Computers - Servers, Terminals and Systems Software

1. Main University Computers

1.0 Prehistory - computers large and small

During the 1940s and 1950s, it became possible to construct very large electronic machines. Some of these were calculators; and some of them were computers. Earlier, in the 1930s, automatic telephone exchanges had been the largest information processing machines in use on the planet, but they were electro-mechanical. Electronic machines, by contrast, tended then to be small (e.g. radios) because anything with a large number of electron tubes was considered, potentially, too unreliable. (Electron tube is the currently preferred term for the former UK valve and US vacuum tube.) When Colossus was constructed at Bletchley Park in the 1940s, it was easily the largest electronic machine on Earth, and it convinced those who knew about it that such machines were feasible, in that that they would not keep breaking down all the time: an important step for the future of computers.

Machines of the size of Colossus - electro-mechanical in the 1930s and 1940s, and electronic in the 1940s and 1950s - were typically arranged as several bays of racking (each bay being filled with chassis filled with circuitry) and a fringe of smaller pieces of equipment, such as teleprinters, standing around it and connected to it by wires. As a convenient way of referring to things, the central racking came to be called the main frame, while the fringe came to be called the peripheral devices. In time, these became mainframe and peripherals.

With the ousting of electron tubes by transistors in the late 1950s, and of discrete transistors by integrated circuits in the late 1960s, computers became smaller. Then, computers that were still large enough to require bays of racking became called mainframe computers. Smaller ones, with just one bay (but not up to the ceiling) were called minicomputers. During the 1970s, there came large scale integration (LSI), and a processor all on one chip - hence microcomputers. By the 1980s, you could fit a computer into a washing machine - whereas, in the 1950s, you could easily have fitted a washing machine into a computer.

Now, in the 21st century, a computer can be powerful without necessarily being large. These terms are relative, of course: a supercomputer used for weather forecasting will be physically large - a mainframe computer if you like - but central computers serving networks are powerful without being remarkably large, even those that serve up simple processing power, and we now call these just servers, not mainframes.

1.1 The Elliott (later ICL) 4130

The University opened its first computer room - large and air-conditioned - in July 1967. Into it came the University's first computer: an Elliott 4130. The building had been funded, and the computer had been funded and chosen, by the Computer Board for England and Wales - see the Narrative page for 1960-79.

As delivered, the 4130 had 16k words of core memory (32 bits per word). It had a fast paper tape reader and a fast paper tape punch, for the input and output of data. It had a rather slow card reader for the input of programs. (It did not have a card punch - these were not common, as they were expensive to buy, to service, and to run.) It had a few (two? three?) magnetic tape handlers, of somewhat low specification.

It had absolutely no on-line access of any kind. Indeed, as evidence of its isolation, the only electrical connections between it and the outside world were the three-phase power cables laid in a trench in the surrounding concrete.

In September 1967, its memory was upgraded to 32k.

In January 1969, at a cost of £50,257, it acquired three disc handlers. These held 'exchangeable disc packs' - the operator could stop the handler running, open the lid of the cabinet, unlock the disc pack, and carry it (it was heavy) to a rack; then take up a different one, carry it across, lock it in place, close the lid, and press the 'run-up' button. Each exchangeable disc pack held one megaword (4 megabytes).

On 6 March 1970, a fourth disc handler was added, and the memory was replaced by a faster, larger one of 64k, which remained for the duration. This upgrade also included eight teletype-33 ASR on-line interactive 'consoles'.

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1.2 The Elliott 4130 + KOS + PDP-11 front end

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1.3 The computer replacement process

Following the invitation to bid, there were the following contenders.

Burroughs ***

Burroughs offered the model 5500 (or 6500?). These seemed at first to be architecturally advanced: they were designed to have virtual memory right from the start, they handled parallel processes elegantly and efficiently (the instruction set operated on a cactus stack), all systems software was written in a high level language (a suitably modified version of Algol: even the Fortran compiler was written in Algol), it could handle a very large number of on-line interactive terminals, and so on. But it had some serious disadvantages.

It was really a transaction-processing system. It was designed to operate in an environment where almost all the terminals interacted with one executing program (or possibly two or three). That is, in an application such as airline seat reservation, or theatre ticket booking. Only a few 'systems' terminals had the privilege of being able to create, modify and delete files, compile programs, and execute object code created by the on-line user. The Burroughs people did not at first understand what we would regard as normal interactive use, and were baffled even when we had explained it.

The other disadvantage, that spoke of its background in commercial data processing, was that its disc memory was a simulation of 80-column punched cards. Each byte represented a column, and all 80 columns were respesented on disc even when they were space characters (in card-speak: 'blanks'). In its intended application involving a uniform sequence of commercial records, that made sense; but when, as in university use, most lines consisted of just a few characters terminated with 'end-of-line' (a concept unknown to the card-based file store), it meant that 95% of the disc represented blanks. That was at a time when discs were very expensive, slow, and physically large but logically small.

A certain British university from the 1960s opted for one of these systems and found out afterwards.
Digital Equipment Corporation
General Electric ***

(This was US General Electric, not UK General Electric Company).

There is now no memory of what they were offering.
International Business Machines

IBM were offering one of the 370 series. To some extent, this system had the same disadvantages as the Burroughs offering.

IBM put up the backs of the Department's internal committee, and to some extent of CSAC, by refusing to talk to anyone 'technical' but sending people in suits and white shirts to talk about money with the Vice-Chancellor.
ICL (2900 series)

2900 series
Rank Xerox Data Systems ***

This was the computer-services subsidiary of the (UK) Rank Corporation that used, and marketed, US Xerox Data Systems computer systems. It was US XDS that withdrew from the computer manufacturing market.

*** During the months when the University was considering these bids, the three suppliers 'starred' above withdrew from the computer manufacturing market - not just from our requirement, but globally, suddenly and completely.

1.4 The DEC-System 10, model: KI-10

In 1976, the entire ICL 4130 system was replaced by a DEC-System 10, model: KI10.

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1.5 The DEC-System 10, model: KL10

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2. Departmental research computers

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3. Departmental servers

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4. Departmental simple terminals

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KSR = keyboard send/receive was an input device (keyboard) and an output device (teleprinter) operating fully duplex using two twisted pairs at 110 baud. With an 11-bit frame containing 8 data bits, that gave 10 ASCII characters per second. ASR = automatic send/receive had an extension bolted on the side that could read and punch 8-hole paper tape as if from the keyboard or to the teleprinter.

5. Departmental Desktop Computers

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6. Departmental computing facilities: from the Handbook

Just for the record, these are straight out of the Students' Handbooks. All that have been changed, for brevity, are (1) use of SWTL and HWTL instead of longer descriptions, and omission of local names of servers.

Room	Terminal	Server	Users
V/058 SWTL	IBM workstations	IBM RS6000/530	undergraduates
X/A001 SWTL	IBM PCs	IBM RS6000/530	MSc and Diploma
X/A006 SWTL	Sun-3 workstations	Sun-3/280	4th year MEng
X/D001 HWTL-1	Sun-3 workstations	Sun-3/280	timetabled lab
X/D003 HWTL-2	Terminals	IBM RS6000/530	timetabled lab
X/T001 SWTL	IBM PCs	???	ITBML undergraduates