I joined a small test and measurement company in Cupertino, California, in 1973. It designed and manufactured transient digitizers, built from analog-to-digital (A/D) converters of its own design. The top of the line was an 8-b, 100-MHz instrument. When IBM got a hold of one, it removed the A/D, installed level detectors, and created an instrument for timing analysis of digital circuitry. Once we discovered IBM’s creation, we perceived that there must be a need for other instruments of that nature. We embarked on a program to develop a line of such instruments.
We displayed several models of logic analyzers at the 1976 WESCON show. As a result of feedback from customers at the show, we decided to embark on the development of a bold new instrument. It would have 16 input channels, individual active high-impedance input probes, a built-in video display, and keyboard control input and be microprocessor-controlled. It was christened the K100-D. The heart of this new instrument was the Motorola 6800 microprocessor.
As the product manager for digital instruments, it fell to me to help the design team interpret the needs of our customers and embody features and functions into this new instrument that would meet those needs. A good bit of my responsibilities included traveling and meeting engineers in the field to discuss their needs. I was able to bring this knowledge back to the factory and share it with the design team.
The K100-D was introduced at WESCON 1978 and became a resounding success. In its first year of production, it outsold its sales projections by a significant factor. However, it turned out that the supply of dynamic RAM, the storage medium for the captured data, became tight. We actually had to redesign the memory boards three times to accommodate whatever high-speed dynamic RAM chips were available. This put major crimps in our delivery schedule.
The input probes were a development struggle: They were conceived as custom hybrid circuits, incorporating threshold detection, overvoltage protection, and mechanical integrity. These became hard-won achievements. Another challenge was the integral graphic display. We decided to incorporate a 7-in raster scan display. The advantages to this type were higher contrast than that of a flying-spot display as well as a larger format. However, we were unable to source a suitable monitor with the requisite display linearity, which was so crucial when displaying timing diagrams. We ended up designing the electronics around an electromagnetic deflection cathode ray tube and achieved display linearity of less than ± 1% across the face of the tube.
At the time of development, a comprehensive emulator for the Motorola 6800 was not available, so we wrote the operating system (OS) code in assembly language and debugged it in situ. The resulting code was compact and executed very rapidly. The OS occupied 28 KB of ROM, and the system had 32 KB of RAM. Finally, to implement automatic testing in manufacturing, every K100-D was equipped with an IEEE 488 interface.
The profits from this instrument funded follow-on instruments that furthered the state of the art in logic analysis.
