In-Situ Emulation

Published in Computer Design October, 1981

This article describes my work to improve in-circuit emulation of single-chip microcontrollers. These components present a particularly difficult emulation problem because they often have I/O ports with special electrical characteristics that are difficult to mimic with other circuitry. The more complex ones, such as the Z8, allow their ports to be reconfigured while running, as illustrated by my later article Popular Micro Configured For Direct DRAM Support. My in-situ emulation techniques were and continue to be the only effective means of emulation in these circumstances.

After this article was published a number of microcontroller manufacturers became interested in my work. I developed the hardware to emulate several chips besides the Z8 but, due to the time required to write all of the software, completed a saleable system only for the Z8. Synertek, a second source to Zilog, sold my emulator under their own brand as the MDT-20.