An electron-beam pattern generator has been made for mask fabrication, either for conventional photolithography or more specifically for making electromasks for use in an image projection system. The maskmaker draws the pattern required at the final size in electron-sensitive resist which in turn defines the pattern in an opaque metal film on a transparent substrate. A 50-mm -square mask covered with detail down to at least 1 μm can be made in less than three hours. To achieve this speed of working two stages of beam deflection are used together with mechanical movement of the substrate. The high-speed deflection system runs at a 10-MHz stepping rate over a maximum amplitude of 32 μm. The slow-speed system covers an area of 2×2 mm. An array of markers predefined over the substrate is used to obtain a pattern accuracy of ±1/8 μm relative to these markers. They are also used to check and, if necessary, correct the beam focus after each mechanical movement of the table. The pattern drawing, positioning, and beam focusing are entirely automatic. An integrated-circuit mask-generation program is used on a larger computer to prepare the data for the patterns to be drawn. Magnetic tape is used to transfer this data to the maskmaker’s small computer.