Steinbuch & Widrow's 1965 paper is a structural comparison of two existing single-layer classifiers, not a study of multilayer network training

widrowsteinbuchmadalinemultilayer-perceptronhistory-of-mlprimary-source-verification

"A Critical Comparison of Two Kinds of Adaptive Classification Networks" is a "Short Note" spanning pp. 737–740 of IEEE Transactions on Electronic Computers, arising from a May 1964 visit by Karlsruhe's Karl Steinbuch to Bernard Widrow's Stanford lab. It compares Steinbuch's "Learning Matrix" against Widrow's "Madaline" on number of outputs, crosspoint weights, adaptations required for training, and equipment ratios (its Tables I–III). Both systems being compared are single-decision architectures: the Learning Matrix assigns one output line per pattern class trained in a single pass, and the Madaline described is the one-Adaline-per-decision or majority/OR-combined form Widrow and Hoff had already published training rules for in 1960–63 (claim-widrow-hoff-1960-original-paper-describes-lms-as-stochastic-steepest-descent).

The paper contains no discussion of hidden layers, credit assignment across layers, or training algorithms for networks with more than one adaptive stage — the word "multilayer" does not appear anywhere in it. This matters because the paper's 1965 date and Widrow's name make it a plausible candidate for "the" attempt at multilayer training this vault's backprop-origins cluster tracks (see claim-widrow-abandoned-multilayer-training-until-1985-backprop and claim-madaline-rule-i-first-layer-trainable-second-fixed); a direct read resolves that it is not. It is a capacity/equipment/training-time comparison paper, unrelated to the multilayer-training problem, distinct from Widrow's genuinely on-topic 1966 paper (claim-widrow-1966-bootstrap-learning-preliminary-multilayer-attempt).