Automated electron beam lithographic tools have throughput requirements which dictate some essential control features. Data of various types flows continuously to and from the tool for deflections, field corrections, patterns, pattern registration, synchronization, and control. Data must be transferred at high speeds and in synchronization with tool writing cycles. In addition, preparation of pattern data and wafer or mask control parameters must be accommodated simultaneously. The IBM electron beam lithographic tool, EL–3, includes a control system driven by two Series 1 (S/1) minicomputers. One is the system controller; the second controls only mechanical operations, such as wafer or mask loading and X–Y stage moving. The primary S/1 controls all system activities through high‐speed memory buffers, a distributed digital control bus which interfaces to functional logic modules, and a direct connection to the S/1 mechanical controller. The buffers allow the primary S/1 to collect or transfer data at its specified rates, while tool functions are executed at high speed by the digital hardware for optimized throughput. The control system can operate stand alone or integrated into a computer‐aided manufacturing environment called Quick Turn Around Time (QTAT). In this QTAT environment, large data volume transfers are made directly into the high‐speed memory buffers at 500–600 kbyte/sec, which improves system throughput for applications requiring frequent pattern buffer reloading. This paper describes the control system configuration, data preparation, data transfer and performance features of EL–3 for both the stand‐alone and manufacturing environments.