paulplatt

Cliches exist because they contain truth in an easy to digest form. There’s an old saying among engineers. “Anyone can build a bridge. It takes a good engineer to do it on time and under budget.”  That one holds the essence of why I consider good engineering more difficult to accomplish than good science. My formal training was as a scientist. I have been around scientific research in both the theoretical and experimental areas and I certainly appreciate the difficulties involved. However, it is the imposition of schedule and budget into engineering that makes it even more difficult than good science. Budget doesn’t just apply to the resources involved in the creation of the item but also involves the cost of manufacture. Great engineering means understanding “Just good enough.” Like many topics in this blog the concept of “Just good enough” is much broader and more important than many people think. It is related to the concept of quality. In his book Quality is Free, Philip Crosby defines quality as “conformance to requirements.” Great engineering meets the customer’s needs in the best manner. Best, in most cases, means finding a solution the customer can afford. For this reason designing a mid sized sedan like the Honda Accord is much more difficult than designing something like a Ferrari Italia. The Accord is in a much more competitive space and has tremendous budget constraints. If you want to upgrade the audio system then you have to find cost savings elsewhere. Many thousands of components have characteristics that must be traded off in order to meet the target price-point. The Ferrari design starts by asking “What’s best?” Just for fun, when it comes to the Accord, you get to layer on tougher customer expectations. The Accord isn’t a showpiece. It is a day-to-day working automobile and must perform perfectly for many years with few service needs. The Ferrari is expected to require some pampering. Even several year old Ferraris usually have just a few thousand miles on them. The Accord is a much tougher design challenge.

One engineer I admire is Steve Wozniak. If you look at the Apple II, the computer that made Apple a real company, you find many examples of awesome engineering. Again and again features are included and performance is achieved with elegant rather than brute force design. The result was a great combination of features at a reasonable price for its day. To highlight what I mean by “just good enough” I am going to single out just one of the many elegant design choices in the Apple II; but first I need to set the stage.

The personal computing era was kicked off in 1975 with the January issue of Popular Electronics. The cover article was on the construction of a computer kit called the MITS Altair 8800. With it came the introduction of the S100 bus. The Altair 8800 was a frame style design where cards were added to increase functionality. While many functions such as main memory have moved to the motherboard, we retain this expansion concept today although the S100 bus has mostly moved into history.

The Altair 8800 was copied by many companies and expanded upon. The S100 bus became an industry standard expansion bus. Lots of companies made cards for the S100 bus. Because of this a lot of computers placed only the basics on the motherboard in an effort to control price. There are problems with this approach. Since there was no game controller (joystick, paddle, buttons) functionality included in the Altair, there was no standardized game interface. I once looked at the cost of adding joysticks to an S100 based computer. The card alone was several hundred dollars. The approach involved expensive analog to digital converters (ADCs). The result was that only keyboard based games evolved for the S100 based machines.

During this time, games like Pong and Breakout were popular. It made sense to bring them to personal computers but they required interactive game controllers i.e. paddles or joysticks. A keyboard used as a controller lacked the same smooth interactivity. Using the keyboard for games was a compromise aimed at satisfying the engineers and accountants and not the customers but it was a compromise most computer manufacturers had adopted. Enter Apple and a few others. In 1977 Apple introduced the Apple II. It came with game paddles along with games like Breakout. To accomplish this in a cost effective manner, Wozniak pushed most of the design into software. Since he had designed Breakout in hardware for Atari, this was a big change in mindset. Great engineers adopt what is best as opposed to just reworking what they did in the past. Simplifying hardware and pushing complexity into software would turn out to be a very important trend. Here was that trend at a very early stage. Look at the schematic below.

This is part of the schematic of the Apple II included in the Apple II Reference Manual dated January 1978. What looks like a 553 integrated circuit (H13) is actually a 558. This is a quad version of the venerable 555 timer chip. The 558 is used to generate four paddle, or two joystick, inputs. Each paddle is just a variable resistor. Hooked into the 558, the resistance of the paddle controller determines the oscillation frequency of a simple RC oscillator. A loop in the code keeps reading the oscillator. The microprocessor can only read a 1 or a 0. If the voltage is above a certain level the microprocessor sees a 1. Below that it sees a 0. The Apple II loops while looking at the game paddle input. By looking at the pattern, for example 111000111000111000, it can determine the frequency of oscillation. This is then related to a game paddle position and the screen paddle is moved to the appropriate screen position. The beauty of this is that the paddle controller doesn’t have to be super linear. The paddles just need to be consistent i.e. all paddles need to act the same way. Nonlinearities can be corrected in software. To the user, using visual feedback as he looks at the screen while turning the paddle, this is all “just good enough.” It is also a high quality solution since it meets the user’s expectations and the requirements for playing games like Breakout. Including games and controllers gave the Apple II great consumer appeal and was a big part of its success and with it the success of Apple Computer.

Today we often see companies just iterating on a theme. These are the so-so companies. Great companies sit back, look at the bigger picture and think about possibilities. Rather than layering expensive, iterative solutions on each other, the great companies rethink the approach and create solutions that are cost effective while meeting user requirements. Exceptional companies go beyond this and create solutions to user requirements that the user didn’t know he had. That, however, is a topic for another post.