Professor David Barron

I have known (even now it’s hard to say “I knew”) David Barron since the mid-1970s and was always uplifted by his sheer delight and interest in programming —  whatever the paradigm and whatever the language.

He always told me that once you’d had the privilege of working with programmers of the calibre of David Wheeler and Christopher Strachey you rapidly got used to discussing everything from assembler level detail (Initial Orders II), to CPL design, to abstract semantics without turning a hair.

Like many others, I first got to know of his written work via the Monographs on “Recursive Techniques in Programming” on and on “Assemblers and Loaders”. The former introduced me for the very first time (and well before the days of Wikipedia) to the delights of the Ackermann Function as an example of something that was recursive but not primitive recursive.  Having just covered `toy’ recursive examples such as “factorial” and “greatest common divisor” in my ARM programming course last semester, I have invited the keen students to try coding up Ackermann “if they think they’re hard enough …”

In the late 70s and early 80s David and I had a lively exchange of views on the rival merits of Algol68 and Pascal.  It was typical of David’s status as a Scholar and Textbook Writer that he was soon in at the deep end writing texts (with Judy Bishop) on PASCAL.

David and I would certainly have agreed that whether there’s a “heaven up there”, or not, is a classic example of undecidability.  But if you *are* up there, David, then please go to the Celestial Electronic Document Vault and pull out, and read, a copy of “Why PASCAL is not my Favorite Programming Language” by Brian Kernighan.

I rest my case!

Now, David was always proud of his association with CPL and its status as the grandparent of the Bell Labs. `C’ language. Thankfully we both agreed that C was a perfectly acceptable language — at least, for people who knew what they were doing.  It combines the precious property of letting you do just about anything you want, while quietly giving you more than enough rope to hang yourself …

I also recall, around the same time, that David wrote a book, with Mike Rees, on UNIX troff. Like me, he delighted in the fact that there is no loop in troff macro syntax and yet there is recursion! So, despite the fact that troff macros seem light years away from a functional language, nevertheless if you want to have a loop in a macro you have to use recursion. Nice one!

You then discover (the hard way) that there are no such things as local variables in troff macros either. Everything is global 🙂

Amid great hilarity we agreed that the final line of the `wizard’ entry, in the much-circulated “UNIX expertise hierarchy” document, was wickedly accurate:

    wizard

           Fixes bugs by patching the binaries

           Writes device drivers with cat > 

           Is on first-name terms with Ken, Dennis and Brian

           Configures an executing kernel using cat > /dev/kmem

           Writes own troff macro packages

In the 1980s David gave me an enormous amount of advice while I was involved in setting up Computer Science at Nottingham from 1984 onwards (and I should also add that Roger Needham and Frank Sumner were invaluable too).

The common heritage of Southampton and Nottingham in giving External London degrees for the first half of the last century meant that much of David’s experience was of very direct help. And that in turn led to two decades of Southampton/Nottingham competition and collaboration in various fields of CompSci.

From the beginning of the email era in the 1980s David was one of my most valued and frequent email correspondents. The earliest email I have from him goes back to 1988 (and that date would have been earlier still, had a catastrophic disk crash, in the early 1990s, not wiped out much of my archived mail).  My `DWB’ mail folder now totals just over 1000 emails over 22 years — not far short of one per week.

David acted as External Examiner for us, here at Nottingham, on many occasions and at every level from undergraduate to PhD. Most recently, in 2005, he was PhD external examiner (in 2005) for my lecturer colleague, here at Nottingham, Dr Steve Bagley.

Steve tells me that the viva was one continuous round of enjoyable but detailed questioning about the implementation details, and the innards of PDF, that led to Steve’s encapsulated PDF document components called COGs.  Although I was Steve’s PhD supervisor, I was not present at the viva, but I could hear the animated debate going on as I walked past the exam. room. Later that day I took  great delight in reading a typical Barron-ism in the first para. of the External Examiner’s report.  This was to the effect that:

” … this candidate *really* knows his stuff” (!).

For the past 10 years or so my face-to-face meetings with David have tended to be at various Cambridge events celebrating “50 years of EDSAC” or in honour of David Wheeler and (most recently) Maurice Wilkes. The last of these, of course, took place only last year. Although David looked very frail he gave a wonderful and affectionate talk about Maurice and the pioneering days of EDSAC (now available online, and as a paper in Computer Journal).

Afterwards his delight was evident when he received heartfelt congratulations and thanks from Maurice’s daughter.

Finally, it was evident to me from the earliest days that there were almost as many “Davids” in computer science as there were “Bruces” in Australia (as depicted in the Monty Python sketch). As an honorary “fourth David” I was introduced to the disambiguating syntax (used by Drs. Barron Hartley and Wheeler at Cambridge) of saying “David (him), David (you) or David (me) ” to make one’s meaning precise.

So, farewell then, David (you).

I’m missing you so very much already.

David (me: Nottm.)

From what has already been said this afternoon we have learned what a remarkable academic career David enjoyed. What may not be as widely known is that, in addition to being a distinguished scientist and learned professor, a loving husband and the proudest of fathers, he was a founding member of the SPG, becoming recently its oldest member. The SPG is a strange and mysterious club with no rules that its members understand. Its weekly meetings are solemnly conducted in defiance of the philosopher Wittgenstein’s dictum that whereof one cannot speak, thereof one must remain silent. In the SPG meetings David contributed in the style many of us will recognise, and it was always evident that if he was not actually disgruntled, he was far from being gruntled. It should be mentioned that what David looked for most from SPG meetings was a reasonably faithful simulacrum of that fabulous elixir Buck-u-Uppo, described by his favourite author as a marvellous specific which, when taken with some food, encouraged the elephants of Indian Rajahs to face tigers in the jungle with jaunty sang-froid. A teaspoonful of the stuff was said to be enough. Naturally, as a distinguished Cambridge-educated academic, David ignored that miserable measure.

Apparently David was keen to have the SPG involved today, as he felt that SPG involvement is likely to keep the sombre moods to a minimum. Hopefully sombre this will not be, so those of a delicate disposition may wish to avert their gaze now.

I could give you my and others’ reminiscences, but fortunately David was a superb wordsmith.

And when email was invented, it was as if it had been made for him personally; many, if not all of us will have had emails that conveyed his pearls of wisdom, or perhaps less elevated thoughts on the state of some aspect of society.

In fact, it feels pretty normal to have David quietly in the background, and today will only be unusual in that when we get home there will be no email from him, providing comment and thoughts on the proceedings.

So, I am just going to read you a tiny few of the thousands of emails from David, to try to paint a portrait of him in his own words, and help you to remember. Although I may have taken extracts, none has been edited. I think they really capture a lot of a complex and very human being.

Let’s go back to the early days. When asked about his paper with Risbeth:

Rishbeth and Barron was *the* classic paper in ionospheric studies

(though as Henry Rishbeth said to me "it did more for my career than it did for yours".)

However, it served me well when CS joined Electronics in 1986.

The old guard in Electronics had very little regard for us. But a few days after the merger, David Stewart approached me and asked in awed tones "are you the Barron of 'Rishbeth and Barron'? When I said yes, I was in!

David told Ray Steele, and Ray then accepted me as someone worthy of respect.

(He didn't change his mind about the rest of the CS staff though.)

In fact, with respect to moving to ECS:

Me, I was brought up in a hard school of academic politics in Cambridge. So when I became HoD, (Buggins' turn) I put the boot in. Within two years, we had a Faculty of Mathematics. (Derek Schofield told me later that "If a bunch of academics want something seriously enough, they will get it." As far as Maths was concerned, I was the one who wanted it seriously enough, and I got it.)

Of course, there was much satisfaction in getting the better of Graham Hills, then Dean of Science. (He accused me privately of eating hot chillies for breakfast.) But the real hidden agenda was that once we had a Faculty, it became much easier to promote the cause of CS. With evident results - as I said, Cambridge was a hard school of academic politics.

BTW, the icing on the cake is that when Mathematics was separated from Science, we got Jim Craggs installed as the Dean of Science 🙂 As I said before, Cambridge was a hard school of academic politics. The easy targets in Soton were like taking candy from a baby 🙂

Jim (Craggs)'s death reminds me of the "fight" to establish Mathematics as a Faculty in its own right. When Jim ended his term as HoD, it had been going on for ten years. Jim was the last of a line of Mathematics Professors who believed that reasoned argument would make the case. They got nowhere.

And again:

P.S Apropos not having the argument, my modest success in academic politics was in no small part due to my learning early on that you should never start something that you know you cannot possibly win. If that's the case, then you resort to 'softlee softlee catchee monkey'. If you're pretty certain you can win you go in with guns blazing. If you're a bit doubtful you wait till the sun is low, and in the enemies' eyes. Worked well for me.

I’m not sure how to introduce this one, but many will recognise it:

Subject: Measurements

Quantum Physics tells us that the act of observation can change what is being observed.

I have a medical example. When an attractive lady doctor wearing a low-cut blouse leans forward to check your pulse ... you have to look away sharpish if you don't want an elevated figure.

And of course, when it came to bureaucracy, he was scathing of the processes expected. It was a matter of pride to him that he reached retirement without ever filling in a Course Evaluation form. Nor was Political Correctness his favourite topic. When asked by the University what his Department was doing to promote women as role models, his response was swift and short: “We employ them as academics.”

Indeed, he was very proud of what he did to help women take their just place in the largely male environment of an engineering department.

The media, government and poor websites were popular targets for his criticism.

The BBC changing its schedules:

Subject: BBC

BBC have just announced that advertised programmes on BBC One are abandoned until further notice so that thay can show Andy Bloody Murray's match at Wimbledon.

Given that the audience share of digital BBC3 is so small as to be almost unmeasurable, why couldn't they can that instead?

David (hoping that Murray will do a Henman)

and

Subject: BBC
Surprise, surprise, the advertised schedule has been abandoned to allow Wimbledon coverage to over-run. And just when you think that at least the tennis is nearly over, you remember that next week it's bloody golf.

And as far as websites were concerned:

... but I'll say it again. What really, really, REALLY pisses me off is e-commerce sites that won't accept spaces in debit/credit card numbers.

Grrr!

David

And of course he woe betide those (especially students) who presumptuously called him “David”, or heaven forfend, “Dave”.

Subject: Another thing that pisses me off

Web sites that require me to register with a me as "David". I prefer Amazon's "Hello D W Barron".

David (to my friends and family)

He was also very proud of his roots. One short email during the census went:

I've been giving much thought as to what I should write in as my religion. Front-runner at the moment is 'Lancastrian'.

David was very fond of his cats. He wrote:

Breakdown of the recent food shopping trip:

Cat food: £8.28
Bird food: £6.09
Food for us: £7.80

Puts my priorities in perspective 🙂

In fact, further shopping messages included the following:

However, on the up-side the Tesco van arrived this afternoon with 12 bottles of Cru Beaujolais at 30% off list price 🙂

Among all this, we must not forget that David was a geek. Only last September he wrote:

The EDSAC 2 had two hardware modifier registers (or three if you include the instruction counter, which could be used as a modifier to achieve position-independent code – another of David Wheeler's inventions). Realising that this might be a limitation, David provided a capability to use any memory location as a modifier. The instruction '2 f n' added the contents of the address field of location 'n' to the address of the following instruction. '2' instructions could be cascaded, and could be modified with the hardware modifier registers, leading to a variety of ingenious tricks.

But David being David, he also introduced a level of indirection with the instruction '4 f n'. This modified the address of the following instruction by the address field of the location pointed to by the address in the '4' instruction. Of course, '4' instructions could be cascaded giving multiple levels of indirection: or you could use a sequence of '2' and '4' instructions each modifying the next, and possibly themselves modified by the hardware registers.

Has to be said that very few programmers used the '2' instruction, even fewer the '4' instruction, and hardly any a combination of the two. That was the ultimate accolade, akin to the top level of Unix skills "writes own troff macros". (Which I did.) Also used the '2' and '4' instructions in my EDSAC 2 programmes. I have a vague recollection that I once managed to achieve a devilish trick by cascading two '4' instructions, but at this distance in time I can't remember the details 🙁

BTW, life's unsolved mysteries: I remember the '2' and '4' instructions, but can't for the life of me remember if there was a '3' instruction in the order code 🙁

Happy days

David

And another short bit of a message:

And should I ever find myself faced with a PDP11/35 with UNIX V6 installed, I would remember that to get it up in single-user (root) mode, you count to ten after the primary bootstrap is completed, then enter '173030' on the keypad 🙂

And he did enjoy technical expertise in others:

Subject: That's ma boy!

Nik, describing his Virgin cable setup, observes that the TV Catch-up Facility is very useful, but the material is copy-protected, so you can't record it.

"Unless I put my little black box in the connection".

That's ma boy!

And David always cared deeply about the way his words looked, as well as the content. An otherwise unremarkable email had the postscript:

P.S Apologies for the mixture of Times 10pt and Courier 12pt in the text above. Eudora has a mind of its own when it comes to fonts and sizes.

But many will have in mind that David was an inspiring teacher. Of course it is hard to find emails from David about his own skills, but I have found some:

Jacky has received a well deserved promotion at King Edwards. But she's not entirely happy with her new title of 'Senior House Mistress'. As she observes, it can be mis-construed, and certainly will be by some of the lads in the Sixth Form.

But I reckon she will cope with them with elan. Runs in the blood. I remember years ago telling an unruly class that "you can try whatever you like, but I've seen it all before, so there's no point".

And another about his teaching:

(Reminds me of the time when the University's 'Teaching and Learning Committee' spent two hours deciding to call itself the 'Learning and Teaching Committee'.

What's wrong with teaching? All through Grammar School and University I had an avid desire to learn. Which was served by a long sequence of inspired teachers, to whom I am eternally grateful. I understand that my Wikipedia entry (I blame Hugh: I've never looked at it) says that I had "an almost unique lecturing style". It wasn't unique at all: it was modelled on all the wonderful teachers who had inspired me in the past. And it was based on the belief that some of the audience were keen to learn, and I had the privilege of passing on the understanding of the subject that I had achieved by the sweat of my brow. And it gave me great pleasure to do so.

And it worked. In my last year of delivering my third-year option on scripting languages, I got the graveyard slot at the end of Friday afternoon. Needless to say, I didn't get a large audience. But those who came were keen to learn. To the extent that several of them would come down to the lecture bench when I'd finished to raise a number of questions that proved they had really been listening. And we carried on an animated discussion until I felt obliged to point out that the bar had opened some time ago, and we were losing valuable drinking time.

David was always a trouper. One message ended with:

Chris Harris was equally supportive. In my final year I mucked in by giving the UCAS recruitment talks. (For most of the season my routine was to go to RSH at 09:30 for Radiotherapy, then get back to Zepler to perform at 11:00.) I have to say, modestly, that on a couple of occasions I got spontaneous applause from the audience, and I got lots of congratulatory comments from the parents who attended.

No big deal: just doing the job in a quaint
old-fashioned way.

In fact, I have a feeling that this might be a nice time to give David a round of applause.

Having had a lot of David’s more recent words, I think we can finish with some from much further back – the final words from his inaugural lecture, in 1971. Despite the bonhomie, wit and sometimes barbs we have heard, I think these words remind us of David as a scholar and gentleman, deeply concerned about the roles of Universities, both in education and creating technological advances, and who never lost his excitement at technology and its relentless march. But most of all we can hear someone who cared deeply about people:

The computer is the most far-reaching of our technological innovations, and like all technology, it can be utilised for good or ill. It is too late to turn back, and bury our processors and peripherals like Prospero’s Book, but we must avoid the danger of being swept along on a tide of innovation. If computers are to be used for good, then it is essential that everyone should understand what they are, and what they can do. Equally, those of us who are behind this technological revolution must gain a greater understanding of our tools, because out of understanding comes judgement.

We are only witnessing the beginning of the changes in Society that the wide-scale use of computers will bring. The changes are not going to be comfortable, but it is the job of those of us in the University to ensure, by education and research, that they are not catastrophic. That is why I am in the game. And, to be honest, it is great fun, too.

In the intervening 40 years it is good to report that with his help and humanity we have not lost the game. And there has been a lot of fun as well.

“Hugh Glaser (with help from the SPG).”

Source: http://www.numberwatch.co.uk/2012%20January.htm

David Barron was a staunch supporter of Number Watch and there are many references to his direct contributions in the archive (see, for example, the Number of the Month for July 2001), though there were far more that are unacknowledged.

He was master of his subject and was once disconcerted to be adversely criticised, during an assessment visitation by a lecturer from a former polytechnic, for lecturing without notes. Computer Science as a new university discipline could well have descended into organised charlatanry, as did some other subjects (e.g. sociology and epidemiology) but a small group of international academics kept it on the rails and turned it into a rigorous discipline. David was one of them. He was not a seeker after fame, which heightens the honour in which he is held by those who knew him and of his works.

What made David influential in the combining of the world’s first electronics department (and an acknowledged world leader) with a younger computer science department was his background as a physicist. Not just any old physicist, but one who had co-authored a notable paper on the ionosphere. Subsequently as a head of the new department he was able to talk to the engineers and physicists on equal terms. At Cambridge he had come under the influence of Maurice Wilkes, known as the father of British computing. The realisation then developed that there was a gaping hole in the state of computer technology, which was the non-existence of a science of programming. This could have reduced the inchoate technology to chaos, which is why David became one of that elite and influential international group who saved the day. He was one of a new breed – the software engineer.

He was also a man of principle and could be very stubborn if pressed to compromise those principles. For example, when that disastrous political folly known as the Research Assessment Exercise was launched, he shrugged off all pressure to join the “paper chase” and continued to produce his thoughtful books every few years. His chosen weapon, however, was the e-mail, issued copiously both locally and internationally. This was medium by which the sound academic discipline of Computer Science was established, from the time when relatively few people knew of its existence, as David’s memoir of Edsger Dijkstra demonstrates. Many of David’s e-mails have become collectors’ items, and I am devastated that I lost my personal collection of these in a recent catastrophic computer crash. They were succinct, witty and, when in attack mode, often acerbically to the point. It was typical of him that, though himself a life-long non-smoker, he fought to the bitter end to preserve a ghetto for the smokers, but this was after the going of Gordon Higginson and the tide of political correctness prevailed. Theirs was a generation for whom that much abused word “liberal” still retained the old meaning, before that definition was turned on its head.

How his contribution is missed in discussion of the most recent foolish proposal to come from the political class, that schools should teach computer programming! I have been programming longer than most, over half a century, and I would not even consider teaching it as a subject, for fear of passing on my bad habits. We engineers and physicists who came under David’s guidance were reluctantly obliged to accept that the computer scientists had a point about the importance of rigour.

It would be a foolish untruth to say that they do not make men like this any more, but perhaps true that they no longer rise to positions of influence.

– Professor John Brignell, a former colleague in the Department of Electronics and Computer Science