DDCMP Protocol on a DMA Serial-Line Board

摘要

The Nuclear Chemistry Division of Lawrence Livermore National Laboratory is in the midst of an upgrade to their radiation counting facility. The result of this upgrade will be a computer-based data acquisition network, the Nuclear Chemistry Counting Facility Network (NCCF-NET). This network will consist of forty dedicated LSI-11/2 based controllers, ten interactive LSI-11/23 based workstations and a VAX-11/750 central node for data reduction and storage. One of the data acquisition instruments used in this network is a Nuclear Data pulse-height analyzer, the ND66L. This analyzer communicates to a host system over a 9600-baud serial line, using the DDCMP link level protocol. In order to relieve the host computer from the overhead of handling the DDCMP protocol, an in-house designed DMA serial line board was implemented to communicate with the ND66L. The hardware used and its environment will be duscussed along with the design and implementation of the firmware, which implements the serial DDCMP link. (ERA citation 08:013008)