Workstation Control of a Pulse Height Analyzer

We are in the midst of upgrading our radiation counting facilities. This upgrade requires control of a Nuclear Data pulse height analyzer (the ND66L) from an LSI-11/23 workstation running RSX-11M. Control of the ND66L includes reading and writing energy spectrums, issuing commands, and servicing device interrupts. The analyzer communicates to the host system over a 9600-baud serial line using the DDCMP protocol. We relieved the workstation CPU from the DDCMP overhead by implementing a DEC compatible DMA serial line board to communicate with the ND66L. An I/O device driver was written to complete the path between the ND66L and the RSX system. The device driver, its use by an application code, and its operating environment will be discussed.