Spelunking CACM, Vol. 16 (1973)

James R. Bell of DEC (Digital Equipment Corporation) (any relationship to Gordon Bell or to the James Bell I went to Caltech with?) wrote a highly-cited article on threaded code that, to my eyes, looks like byte-code compiled code for an interpreted language, as in the figure above. (The figure doesn't quite convey the distinction between the left and right figures, but it's there). On the CPUs of the 1990s this many jumps would totally trash your pipeline and possibly your cache, though today's CPUs invest a lot of effort in branch prediction and the like such that some of those jumps could cost as little as zero cycles, though the indirect through a register could make that harder.

Before the late-80s trend toward language-agnostic RISC systems that put the onus of efficiency on compilers and run-time systems (and ignited the most ferocious era of Moore's Law-enabled competition), it was common in systems research to consider hardware architectures that were tuned toward execution of a specific language. A team from IBM microprogrammed an IBM 360 model 25 to accept a baroque machine language specifically for APL. I rather miss those days; I was a fan of the Lisp machines of the 1980s, though there were among the first and most thorough victims of the Killer Micros.

 It's interesting to note that people have been concerned that we might have too many PhDs for half a century now. Such opinions seem to alternate (during boom times) with the fear that we don't have enough, that we are eating our seed corn (to leap ahead to 1981 in CACM for a minute).

We have done a little work on clique finding on quantum computers, so I probably should be more familiar with the work of Bron and Kerbosch. I am rather deliberately not looking just for articles that are highly cited; that would be boring and wouldn't really help anything. Instead I am looking for trends as well as things that just catch my fancy, as clever or prescient or sometimes extra-far off base. But this one might be the single-most cited paper in CACM in calendar 1973, and so is interesting for that reason as well as the overlap with my own work.

Overall, my impression of 1973 is that it was a year of "settling in", of solid but mostly not groundbreaking work, at least as represented in CACM. Soon enough, though, we will be into the Xerox PARC, home PC and UNIX workstation eras...looking forward to seeing how CACM changes. Next stop: the current half-century!