Lay Out Rcas Experimental Pmos Shift Register First Mos Integrated Logic Demonstration

# Lay Out RCAs Experimental PMOS Shift Register: The First MOS Integrated Logic Demonstration

## 1. Why a Shift Register, Specifically, Was the First Circuit Built This Way

RCA's experimental PMOS integrated circuit group chose a shift register as the first circuit to build from multiple interconnected MOS transistors on one chip, because a shift register's clocked, dynamic charge-storage operation plays directly to a MOS transistor's single strongest structural advantage over a bipolar equivalent: a MOS gate's own input capacitance can be used as the circuit's storage element, with no separate capacitor or bipolar latch needed. Each stage stores a bit as charge on a gate capacitance and transfers it to the next stage on a clock edge — a mechanism that does not exist, even in principle, in a resistor-transistor or diode-transistor bipolar gate:

Lay Out RCAs Experimental PMOS Shift Register: The First MOS 1. Why a Shift Register, Specifically, Was the First Circuit Built This Way DYNAMIC SHIFT-REGISTER STAGE, CHARGE AS THE BIT gate capacitance holds charge = bit clock edge next stage, same mechanism no equivalent exists in RTL or DTL this is a circuit function MOS could do that bipolar logic structurally could not, not merely do more cheaply

## 2. Real Diagram: The Actual Chip Layout RCA Demonstrated

The demonstration chip laid out a modest number of stages — enough to prove the concept, far short of commercially useful density — with gate electrodes, source/drain diffusions, and metal interconnect all visible as distinct, individually inspectable layers, the same layered-fabrication logic this project's bipolar and planar series already document, applied here to a field-effect rather than junction device.

Real Diagram 2. Real Diagram: The Actual Chip Layout RCA Demonstrated gate electrodes, repeated per stage metal interconnect bus, clocked a small, demonstrably working number of stages — proof of concept, not yet a product the first time a MOS integrated circuit, not just a MOS transistor, had been shown to work at all

## 3. The Actual Chip Layout RCA Demonstrated

This demonstration did not ship as a product and did not by itself settle the bipolar-versus-MOS question for commercial logic — it settled only the narrower question of whether multiple interconnected MOS transistors on one chip could be made to function together, which, until this point, had not been shown.

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