Binary Up/Down Counter M211

This document is a technical schematic for a Digital Equipment Corporation Binary Up/Down Counter (Model M211). It illustrates the circuit logic used to perform up/down counting operations, utilizing integrated circuits (specifically series 7400 TTL chips such as the 7474, 7450, 7400, and 7440). The schematic details the connections for flip-flops, input gating for enable and up/down control, carry-out functionality, and power distribution (+5V and ground). Additionally, it provides a comprehensive parts list, including specific integrated circuit model numbers, resistor values, and capacitor specifications, along with general assembly notes for maintenance and testing purposes.