Fast digital data acquisition and on-line processing system for an HB5 scanning transmission electron microscope

The Fast Digital Data Acquisition System (FDDAS) links a Vacuum Generator’s HB5 Scanning Transmission Electron Microscope and a PDP‐11/34 minicomputer, to enable high‐speed collection and storage of digitized images for analysis, processing, and display, either in real time (using hardware) or later (via software). The FDDAS hardware consists of a digital scan generator, a programmable quad scaler with quad discriminator, an on‐line processor with digital gray level generator, an analog to digital converter, and a joystick. These devices are interconnected as addressable locations on the FDDAS bus line, the ’’System Bus,’’ on which they can act as data sources or sinks. The FDDAS also contains the circuitry for interfacing the system bus to the PDP‐11 UNIBUS, allowing it to read or write image data into the computer at memory cycle speeds. The FDDAS software consists of data transfer, data reformatting, and test pattern generation modules which are linked in an overlay structure and designed to execute un...