EARLY TRANSISTOR HISTORY AT IBM

Hannon S. Yourke

Oral History – (Continued)
	HISTORIC 1957 IRE PAPER The images on this page are excerpts from the classic paper by Hannon Yourke, “Millimicrosecond Transistor Current Switching Circuits”, published in the September 1957 IRE Transactions on Circuit Theory. In this paper, Mr. Yourke presents the basic description and circuit operation of current switching (ECL) circuits. Figure 1, seen above, shows the basic transistor block operating in ECL mode. Figure 5, shown in the upper left, is an example of a typical logic circuit developed with current switching - in this case, the logic circuit is an N-way complemented “or” circuit, which was extremely useful in computer operation and became one of the circuits used in the IBM Project Stretch and later IBM solid state computers. The operation of the circuit is shown as input and output waveforms on the oscilloscope photograph (Figure 6), which was also presented in the paper. The significance of this work by Hannon Yourke on early transistor logic circuits was recently recognized by the IEEE International Solid State Circuits Conference, which documented this work as one of the 70 most outstanding ideas spanning the last 50 years of solid state history. This work was also documented in U.S. Patent 2,964,652, which was filed by Mr. Yourke in November 1956 and granted in December 1960. ______________
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