Fifty Years of Programming
and Moore's Law

by John Walker
November 4th, 2017


Univac 1107 console with tape drives behind As best as I can determine, it was around fifty years ago, within a week or so, that I wrote my first computer program, directing my life's trajectory onto the slippery slope which ended in my present ignominy. This provides an opportunity for reflection on how computing has changed in the past half century, which is arguably a technological transition unprecedented in the human experience. But more about that later. First, let me say a few words about the computer on which I ran that program, the Univac 1107 at Case Institute of Technology, in the fall of 1967.

It Was Fifty Years Ago Today…

In the 1960s, the Univac® 1107 provided the main computing facility for Case Institute of Technology in Cleveland Ohio in the United States. Operated by the Andrew R. Jennings Computing Center, the “Seven” enticed a generation into the world of computing and, with the innovative “fast turnaround batch,” “open shop” access pioneered at Case, provided a standard of service to a large community of users almost unheard of at the time. The Case 1107 was immortalised by being included by Case alumnus Donald Knuth in the calculation of the decimal representation of the MIX 1009 computer in The Art of Computer Programming.

In the view above, we see the system console at the right, in front of the bank of UNISERVO™ II-A tape drives. The rounded cabinet at the very left of the frame is part of the TRW 530 “Logram computer”, which was used primarily to convert tapes between UNISERVO II-A 200 BPI format and the 800 BPI IBM-compatible format used by the UNISERVO VIII-C drives on the 1108 at Chi Corporation.

Central computer cabinet

The Univac 1107 was massive, but quiet. All its main cabinets went from floor to ceiling, with air conditioned air injected under the raised floor and exit air exhausted over the dropped ceiling. Most of the central computer cabinets were walk-in. This one contained the main processor logic and the 65,536 36-bit words (about 256 K bytes) of core memory. Memory access time was 8 microseconds per word, but interleaving of instruction and data accesses allowed average access time to approach 4 microseconds in ideal conditions.

FH-880 magnetic drum

Mass storage for the single job run at a time, and for queueing waiting jobs and printer output for those already complete, was provided by the two FH-880 magnetic drums, one of which is shown above, which together provided about 6 megabytes of random access storage.

Maintenance panel

The central processor was a 36 bit architecture, capable of executing most simple arithmetic instructions in one 4 microsecond cycle time. Multiplication of two 36-bit integers took 12 microseconds, and division of a 72-bit dividend by a 36-bit divisor 31.3 microseconds. The processor performed 36-bit single precision floating point arithmetic in hardware, but did not implement double precision floating point.

High speed reader and line printer

The high speed printer and card reader were connected directly to 1107 I/O channels. The printer was a rotating drum and hammer device which printed 600 lines per minute. The card reader read 600 cards per minute with two sets of brushes to read and verify the card; if they did not agree, reading would halt. Cards were grasped by a vacuum-equipped feed arm and fed into the mechanism.

The “card eater” was notorious for jamming, sometimes demolishing student card decks which had been fed through numerous times in the process of debugging a program. Note the prominent Emergency Stop button to the right of the throat which ingested the card deck. Fortunately, students in the “open shop” environment in which the 1107 operated quickly learned how to field-strip the card reader and remove the remains of their programming projects when this happened.

24-hour clock and Computer Is Available signThe high speed printer was derived directly from a printer used on the Univac I. Its hammers were driven by a bank of thyratron (gas-filled power switching) tubes which were visible when the back of the printer was removed. When the drum advanced so the desired character was approaching the hammer, the tube would fire and whack the paper against the drum from the hammer bank behind the page. The printer incorporated a feature known as the “all out detector” which, if one or more hammers failed to fire on a given line, leaving their corresponding drive tubes not “out” (you could see the gas in them glowing until they fired), halted the printer, permitting the operator to examine the printer controller, note the missing characters, open the printer carriage, write them into the columns they belonged with a pencil or pen, then restart the printer. The pace of life was so much slower then….

Also memorable about the high speed printer was that, due to its both consuming and storing relatively large amounts of energy, along with a supply of paper, its front panel was equipped with a Fire indicator light and, directly below, an Extinguish button. I was a very different person in those distant days of yore, and never pushed Extinguish to see what, if anything, it did. However, one Friday night while the system programmers and system programmer wannabes (myself falling into the latter category) were watching Star Trek in the hardware engineers' room (first airing of The Original Series, you understand!) the Extinguish button lighted up spontaneously without any obvious effect; a few switch flips turned it off.

Keypunch room

All jobs (“runs”) were initiated by reading in decks of punch cards from a card reader. Above is the main keypunch room where most users prepared their programs. This room was open to anybody, 24 hours per day, and was equipped with IBM model 026 manual card punches. The individual at the keypunch is unidentified. Visible through the window at the end of the keypunch room is the computer room, with the Univac 1004 card reader/punch and printer unit in the foreground.

The UNIVAC 1004 reader/printer/punch

Here's a view of the 1004, with the keypunch room in the background. This machine read 300 cards per minute and printed 300 lines per minute. Though slower than the high speed reader and printer, it was more reliable and its output generally more legible, so many preferred it. Its card punch (at the left) was an awesome machine that punched an entire 80 column IBM card all at once. A huge electric motor powered the beast, and the GRRRrumble and then whump, whump, whump when it came to life brings back memories even today. The reader/printer unit is to the right. Punch cards were introduced into a hopper to the right of the printer and followed a tortuous path before emerging vertically in the bin visible at the right of the unit. This bin was slanted upward slightly and a weight with wheels on the bottom held the cards in place as the deck filled the exit bin. If you happened to feed a deck into the 1004 when this weight wasn't in place, the cards would spray out of the reader through the air every which way, completely scrambling the contents. This was extremely amusing to watch, as long as the cards weren't yours.

The 1004 jammed less frequently than the high speed reader, but when it did jam it could do so heroically. The high speed reader never destroyed more than a single card at a time, but the 1004 could jam in ways not detected by the machinery, which continued to feed more and more cards to their certain doom, until their torn remains sufficiently clogged the works to bring things to a halt. As I recall, the record for the number of crumpled and shredded cards removed from a single 1004 jam was 17, but I believe that was a 1004-II which ran twice as fast and was even more prone to jamming. Still, it was not unusual to lose four or five cards in a 1004 jam.

2400 baud modem

The Case 1107 was one of the first computers on Earth to provide access from remote locations both at other places on the campus and as far afield as Erie, Pennsylvania. This is the 2400 baud leased line modem used for one of those connections. Now, if you have a modem, you need a port to hook it up to. Here's a pair of 2400 baud serial ports, 1960s style.

Communications Terminal Synchronous (Serial Port)

This floor-to-ceiling box (the file drawers for punch cards on either side provide a sense of scale) was called the CTS—short for “Communication Terminal, Synchronous”. It could contain either one or two synchronous serial ports, each on a dedicated I/O channel. This CTS has two ports; the vertical rows of round lights show input and output activity on each port. Not only did the CTS consume an entire I/O channel for each port (the 1107 only had 16 channels—you could put 16 tape drives on a channel or…one serial port), it was a prodigious memory hog. Input and output were stored with a single six bit character in each 36 bit word. If you transmitted and received small blocks of 1024 characters, and ran half-duplex so you didn't need separate input and output buffers, the data buffer for a single remote terminal would still consume 1/64th of the entire 65536 word memory of the 1107.

Programmers around the console

Day and night, the 1107 attracted individuals fired by the sense of wonder of what such a machine and its descendents, properly programmed, might do during their lifetimes. In this picture, from left to right, are John Richards, Ken Walter, John Langner, and Gene Hughes. John Walker snapped this candid picture.

The Quail Building at Case Institute of Technology, c. 1966

The 1107 was installed on the first floor of the Quail Building, shown above in a photo taken around 1966 by Bill Patterson. This is the same building which previously housed Case's Univac I and Burroughs 220 computers. The keypunch room was on the near end of the left face of the building in this view, and the 1107 occupied the far half of the ground floor.

A Sense of Scale

The Univac 1107 I used in 1967 (which was, at the time, reaching the end of its service life, and would be replaced the next year by its successor, the Univac 1108) had a fundamental instruction clock rate of 250 kHz: it could execute simple instructions such as add, subtract, and jump in around 4 microseconds, or 250,000 such instructions per second. By the standards of 1967, this was pretty impressive: heck, it's a lot faster than I can do such things, and it was sufficient to meet the need for research and instructional computing for a university with around 3,000 students. Let's look back at it from the perspective of today's computers.

Dell Precision 7710 I am writing this on a modest laptop whose processor runs at 3 GHz: three billion instructions per second. Simply based upon the clock rate, my current machine, fifty years after I ran my first program, is twelve thousand times faster than the first computer I used. But that isn't the whole story. The Univac 1107 had a single processor, made of discrete transistors on circuit boards in a cabinet the size of a kitchen. My laptop has eight processors, able to all run in parallel, and if I manage to keep them all busy at the same time, I have 96,000 times the computing power at my fingertips. Further, the instructions are more powerful: the 1107 was limited to 36 bit integer and floating point computations: more precision required costly software multiple precision, while my laptop has direct hardware support for 64 bit quantities. This is probably worth another factor of between two and four for applications such as graphics, multimedia, and scientific computation.

Univac core memory plane from the Fourmilab Museum. What about memory (or, as I prefer, storage)? You can't do all that much with computing power if you don't have the space to store the data you're crunching. In 1967, most programming was a constant battle to work around the constraints of limited storage. Every bit in a core memory plane had to be wired by a human, peering through a magnifying glass, threading almost invisible wires through tiny ferrite toroidal cores—no wonder these memory devices cost a fortune. The Univac 1107 had 65536 words (“64K”) of 36 bit core memory or, roughly converting into present-day terminology, 256 kilobytes of RAM (random-access memory). And my laptop in 2017? Well, it has 64 gigabytes of RAM. Let me write these out with all of the digits to make this clear. The Univac 1107 in 1967: 256,000 bytes; my laptop in 2017: 64,000,000,000 bytes. That's 250,000 times as much memory. Imagine how many cat videos I can store!

Now, let's look at what we used to call mass storage, although by present standards it was laughable. The Univac 1107's two FH-880 magnetic drums provided a total of around 6 megabytes of storage, which was mostly used to buffer input and output to the computer and provide scratch storage to programs. My laptop has three solid state drives with a total of three terabytes (trillions of bytes) of storage: 500,000 times that of the 1107 (in fact, the laptop has so much storage I've opted to mirror all of my data on two drives, halving the available storage in the interest of redundancy should one drive fail). And my laptop is a few years old: today I can buy a six terabyte hard drive at the supermarket.

Floating Point Benchmark

All of these big numbers—megas, gigas, and teras—tend to make one's eyes glaze over. Let me provide a personal perspective on the revolution in computing power during my career. Ever since the 1970s, my strategy has been to identify applications which, in order to be useful, required more computing power than was presently available to its potential customers, and then begin development with the goal of, when the product was ready to bring to market, the exponential growth in computing power at constant cost would make machines available which could run it. This was the central strategy of Autodesk, Inc., the company I co-founded in 1982, and whose first product, AutoCAD, only came into its own with the introduction of the IBM PC/AT and other 80286 machines in 1984. In order to keep track of the evolution of computer power, in 1980, I created a floating point benchmark which measures the performance of various computers on a scientific computation task which was a model for those I intended to bring to market. A “benchmark”, in computing, is a program, usually simple and easy to adapt to various computing environments, which models the performance of those systems on more complex tasks you're interested in running. My benchmark, based upon ray tracing to analyse the performance of optical systems, ended up being uncannily accurate in predicting how fast a given computer and software environment would run AutoCAD. If you were interested in word processing, crunching large databases, or other applications, its results weren't useful, but as a model for scientific and engineering computation, it was unreasonably effective.

I first ran the benchmark in 1984 on an IBM PC/AT. Now, bear in mind, this machine was more than three times faster than the original IBM PC on which we had launched AutoCAD in 1982. Running the benchmark for the standard of 1000 iterations, it ran in 3290 seconds in Microsoft BASICA and 2132 seconds in the C language in which we implemented AutoCAD. Note that there are 3600 seconds in an hour. Not long after, Apple announced the Macintosh, and their Macintosh Plus ran the benchmark in 1598 seconds, less than half the original Microsoft figure. Amusingly, my Marinchip machine, first delivered in 1978, beat the much-vaunted Macintosh at 1582 seconds.

Then things really began to take off. Microsoft optimised their BASIC, and QuickBASIC cut the run time to 404 seconds. The introduction of the 80287 floating point coprocessor allowed a C compiler to complete the benchmark in 165 seconds. Workstation machines and increasingly optimised personal computer hardware and software contended throughout the 1980s, and by the end of the decade the Intel 80486 was running the benchmark in 1.56 seconds—more than two thousand times faster than in 1984. But, notwithstanding the prophets of stagnation who said, “surely, this must end”, the exponential curve continued to climb to the sky, and before long the one second barrier had been breached by the RISC processors of the 1990s, and then even those marks were dwarfed by the runaway increase in clock rates in the 2000s. My current laptop, which is far from the highest performance machine available today, runs the benchmark in 0.00862 seconds. What used to take almost an hour in 1984 now can be completed in less than a hundredth of a second: this is an increase of speed of a factor of 381,671 times, and the laptop which delivers this performance costs a fraction, in constant dollars, of the personal computer in 1984.

But wait, there's more. Through most of this history, computers had only a single processor, or computing element. They processed the tasks they were assigned one at a time. They may have flitted from one to another to provide the illusion of concurrency, but that didn't get things done any faster than if they'd done them in order. In the 2010s, it became more difficult to increase the clock rate (fundamental speed) of microprocessors, but the ability to put more and more transistors on a silicon chip continued to increase. As a result, we began to see the emergence of processors with multiple “cores”: separate processors on a single chip, which could simultaneously execute different tasks independently. Now, you could watch a cat video, build your killer app, and produce your next YouTube hit simultaneously on one machine because different processor cores were working on these jobs at the same time. Fourmilab's main in-house server has 64 processor cores, all running at 3 GHz. If I get them all running at the same time on my floating point benchmark, it completes in (normalised to the original execution time) 0.00027 seconds, or 12,115,113 times faster than the first machine to run the benchmark in 1984: a factor of more than twelve million in thirty-three years.

To trot out a tired analogy, had automotive technology advanced at the same rate as computing, the successor to the 1972 red Volkswagen bus I drove in 1984 would be able to cruise at one billion miles per hour (one a half times the speed of light), get 200 million miles per gallon (about the diameter of the Earth's orbit around the Sun) and, if it used any Microsoft products, explode randomly every few days, killing everybody on board.

Moore's Law

What's going on here? In 1965, Gordon Moore, co-founder and director of research and development at Fairchild Semiconductor, and later co-founder of Intel, forecast that, over the next ten years, the number of components it would be possible to cram onto a silicon integrated circuit (chip) of constant size and at constant cost, could be expected to roughly double every year. He wrote, in an editorial in Electronics magazine,

The complexity for minimum component costs has increased at a rate of roughly a factor of two per year. Certainly over the short term this rate can be expected to continue, if not to increase. Over the longer term, the rate of increase is a bit more uncertain, although there is no reason to believe it will not remain nearly constant for at least 10 years.

In 1975, Moore revisited his prediction, which so far had been borne out by progress in integrated circuit design and fabrication, and further predicted that complexity at constant cost would continue to double until around 1980, after which it was expected to slow, but continue to double every two years thereafter. He placed no upper bound on this forecast, although obviously there are ultimate limits: the components fabricated on integrated circuits are composed of atoms, and atoms have a finite size. At some point, as you make things smaller and smaller, you'll reach a scale where device geometries approach the atomic scale and there are just aren't enough atoms to fabricate the structures you're trying to make (and, in addition, quantum effects become significant and change how electrons behave). But those limits were far in the future when Moore made his forecasts, and they're still far away from our present technology. Shortly after Moore's revised 1975 forecast, Caltech professor Carver Mead coined the term “Moore's law” for this anticipated compounded exponential growth in transistor density in integrated circuits.

Now, everybody understood at the time that “Moore's law” was not a law of nature like Newton's laws of motion or gravitation, but an observation about technological progress and that there was no apparent law of physics which prevented the increase of component density from continuing to grow exponentially over a period spanning decades. For this to actually happen, however, engineers would have to become ever more clever at designing smaller devices, figuring out how to fabricate them on silicon at geometries which would approach and then decrease below the wavelength of visible light, and fund the research and development required to figure out how to do all of this. And this presupposed that there would be applications and markets for these increasingly powerful and sophisticated devices which would generate the sales needed to fund their development. From the perspective of the 1970s, it was entirely possible that sometime in the 1980s the market would decide that computers were fast enough for everything people wanted to do with them, that after every office desktop had a computer there was no further mass market that sought more computing power, and consequently the investment required to keep Moore's law going wouldn't be forthcoming. In the early 1980s, I bet my career that this wouldn't happen. And it didn't. What did happen? This….

Moore's Law: 1971–2011

Seldom in the human experience has compounded exponential growth such as this over a period of decades been experienced. Moore's forecast, originally made more than half a century ago (two years before I wrote my first computer program) has been proved to be almost exactly precise over time. Note that the chart above is on a semi-logarithmic scale: the time scale at the bottom is linear, but the transistor count scale at the left is logarithmic: each equal interval represents a power of ten in the number of transistors per chip.

“All right”, you ask, “every two years or so we can shoehorn twice as many transistors onto a chip at around the same price. But what does that mean?” It is central to the technological revolution through which we're living. For computer memory it's pretty simple to understand: for about the same money, every two years you can buy a digital camera memory card, USB drive, or other storage device that holds twice as much data as the previous generation. Over time, this compounded growth is flabbergasting. I remember when I thought a 48 megabyte compact flash memory card for my digital camera was capacious. The most recent card I bought is a much smaller secure digital card with a capacity of 256 gigabytes: more than five thousand times greater. This same growth applies to the main memory in our computers and mobile gadgets: my first personal computer in 1976 had a RAM capacity of 256 bytes. As I noted above, my current machine's capacity is 64 gigabytes: two hundred and fifty million times larger.

Intel SDK-80 single-board computer (1976)But when you make transistors smaller, they don't just shrink: the Dennard scaling theorem kicks in. It's a win-win-win-win proposition: not only can you put more transistors on the chip, allowing more storage and increased complexity in computer processors, each transistor can switch faster and uses less power for each switch, thus dissipating less heat. (This is pretty easy to understand: as the size of the transistor decreases there are fewer electrons which have to flow through it when it switches, so it takes less time for them to flow in and out, and they require less supply current and release less heat with each switch—this is oversimplified [I don't want to get into device capacitance here], but it should be sufficient to explain the idea.) So, you don't just have more memory: processors can be more complicated, adding instructions for things like floating point, graphics, and multimedia operations, adding computing cores to allow multiple tasks to run simultaneously, and employing a multitude of tricks, clean and dirty, to speed up their operation, all without paying a cost in higher power consumption or waste heat generation. Again, let me put some numbers on this. That first personal computer in 1976 ran at a clock rate of 0.5 MHz, executing an around 500,000 instructions per second. My current laptop has a clock rate of 3 GHz, running around 3,000,000,000 instructions per second on each of its 8 processor cores, for a total of 24,000,000,000 instructions per second (if I can keep them all busy, which is not the way to bet). Thus, the laptop is 48,000 times faster than my first machine.

In short, the number of transistors we can put on a chip is a remarkably effective proxy for the computing power available at a constant cost. And as that continues to double every two years, it changes things, profoundly.

The Roaring Twenties

Where's it all going? We have experienced a spectacular period of exponential growth over the last fifty years. In fact, I cannot think of a single precedent for such a prolonged period of smooth progress in a technology. Usually, technologies advance in a herky-jerky fashion: sitting on a plateau for a while, then rushing ahead when a technological innovation occurs, and then once again stagnating until the next big idea. For example, consider aviation. The first Wright brothers' airplanes were slower than contemporary trains. It wasn't until the development of metal, multi-engine airplanes decades later that commercial aviation became viable. Progress was slow and incremental until the advent of jet propulsion, developed during World War II but not widely applied until the 1950s. While great progress has been made in reliability, safety, and efficiency, today's jetliners fly no faster than the Boeing 707 in 1957. Supersonic transport was shown possible by the Concorde, but proved to be an economic dead end. By comparison, in computing the beat has just gone on, year after year, decade after decade (indeed, if you extend the plot backward to the development of Hollerith machines and mechanical calculators in the 1800s, for more than a century), with hardly a break. Technologies have come and gone: electromechanical machines, vacuum tubes, discrete transistors, and integrated circuits of ever-increasing density, but that straight line on the semi-log plot just continues to climb toward the sky.

At every point in the last fifty years, there were many people who predicted, often with detailed justification based in physics or economics, why Moore's law would fail at some point in the future. And so far, all of these forecasts have been proved to be wrong. As David Deutsch likes to say, “Problems are inevitable”, but “Problems are soluble.” Engineers live to solve problems, and so far they haven't encountered one they can't surmount. Everybody who has bet against Moore's law so far has lost, and those of us who have bet our careers on it have won. Some day, it will come to an end but, so far, this is not that day.

What happens if it goes on for, say, at least another decade? Well, that's interesting. It's what I've been calling “The Roaring Twenties”. Just to be conservative, let's use the computing power of my current laptop as the base, assume it's still the norm in 2020, and extrapolate that over the next decade. If we assume the doubling time for computing power and storage continues to be every two years, then by 2030 your personal computer and handheld (or implanted) gadgets will be 32 times faster with 32 times more memory than those you have today.

Only a Human... So, imagine a personal computer which runs everything 32 times faster and can effortlessly work on data sets 32 times larger than your current machine. This is, by present-day standards, a supercomputer, and you'll have it on your desktop or in your pocket. Such a computer can, by pure brute force computational power (without breakthroughs in algorithms or the fundamental understanding of problems) beat to death a number of problems which people have traditionally assumed “Only a human can….”. This means that a number of these problems posted on the wall in the cartoon are going fall to the floor some time in the Roaring Twenties. Self-driving cars will become commonplace, and the rationale for owning your own vehicle will decrease when you can summon transportation as a service any time you need it and have it arrive wherever you are in minutes. Airliners will be autonomous, supervised by human pilots responsible for eight or more flights. Automatic language translation, including real-time audio translation which people will inevitably call the Babel fish, will become reliable (at least among widely-used languages) and commonplace. Question answering systems and machine learning based expert systems will begin to displace the lower tier of professions such as medicine and the law: automated clinics in consumer emporia will demonstrate better diagnosis and referral to human specialists than most general practitioners, and lawyers who make their living from wills and conveyances will see their business dwindle.

The factor of 32 will also apply to supercomputers, which will begin to approach the threshold of the computational power of the human brain. This is a difficult-to-define and controversial issue since the brain's electrochemical computation and digital circuits work so differently, but toward the end of the 2020s, it may be possible, by pure emulation of scanned human brains, to re-instantiate them within a computer. (My guess is that this probably won't happen until around 2050, assuming Moore's law continues to hold, but you never know.) The advent of artificial general intelligence, whether it happens due to clever programmers inventing algorithms or slavish emulation of our biologically-evolved brains, may be our final invention.

References and Further Reading

Photo and image credits:

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