Concept
Direct-coupled transistor logic
Overview
Direct-coupled transistor logic (DCTL) is similar to resistor–transistor logic (RTL), but the input transistor bases are connected directly to the collector outputs without any base resistors. Consequently, DCTL gates have fewer components, are more economical, and are simpler to fabricate onto integrated circuits than RTL gates. Unfortunately, DCTL has much smaller signal levels, has more susceptibility to ground noise, and requires matched transistor characteristics. The transistors are also heavily overdriven; this is a good feature in that it reduces the saturation voltage of the output transistors, but it also slows the circuit down due to a high stored charge in the base. Gate fan-out is limited due to "current hogging": if the transistor base–emitter voltages (VBE) are not well matched, then the base–emitter junction of one transistor may conduct most of the input drive current at such a low base–emitter voltage that other input transistors fail to turn on.
DCTL is close to the simplest possible digital logic family, using close to fewest possible components per logical element.
A similar logic family, direct-coupled transistor–transistor logic, is faster than ECL.
John T. Wallmark and Sanford M. Marcus described direct-coupled transistor logic using JFETs. It was termed direct-coupled unipolar transistor logic (DCUTL). They published a variety of complex logic functions implemented as integrated circuits using JFETs, including complementary memory circuits.
Overview adapted from Wikipedia (CC BY-SA 4.0; see the article history for authors).
Possible passages
Found by search and not yet checked by a person; they may only mention the idea in passing.
Such a prolonged station will be called a point-track. A point-track is a locus of event-particles. It is defined by reference to one particular time-system, {alpha} say. Corresponding to any other time-system these will be a different group of point-tracks. Every event-particle will lie on one and only one point-track of the group belonging to any one time-system.
Alfred North Whitehead, The Concept of Nature The Tarner Lectures Delivered in Trinity College, November 1919
States what Direct-coupled transistor logic is.
g._, for _j_ = _x_. (AB_{_x_}) = A_{_y_} B_{_x_ _y_} - A_{_z_} B_{_z_ _x_}. Correspondingly let us define in the four-dimensional case the product (P_f_) of any four-vector P and the six-vector _f_. The _j_-component (_j_ = _x_, _y_, _z_, or _l_) is given by (P_f__{_j_}) = P_{_x_}_f__{_j_ _x_} + P_{_y_}_f__{_j_ _y_} + P_{_w_}_f__{_j_ _z_} + P_{_z_}_f__{_j_ _l_} Each one of these components is obtained as the scalar…
Albert Einstein, The Principle of Relativity
Close in meaning to Direct-coupled transistor logic; the term itself is not named.
This was by operating on a circuit _C_ composed of two parts, the one fixed, the other movable. The movable part was, for instance, a movable wire [alpha][beta] whose extremities [alpha] and [beta] could slide along a fixed wire.
Henri Poincaré, The Foundations of Science
Close in meaning to Direct-coupled transistor logic; the term itself is not named.
Related ideas
Place in the tradition
Part of Logic gate.
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