Abstract
The function of the sytem is to determine step voltages for scanning gases to bemeasured, and to make simultaneous and continuous measurement of the specified mass ions by a rapid and repeated supply of the step voltages and gate pulses. The system is composed of a microcomputer scanning system and an analogue gate assembly. The microcomputer system is composed of an A/D converter(ADC550-10-E), a D/A converter(DAC371V-8)and a SDK-80system(8080CPU, ROM2KB, RAM1KB and a programmable peripheral interface 8255). The 8255 plays an important role as an I/O port in the construction of the interface. The design construction of the system is illustrated and the operation of the system is described in details. Some technical points are examined and discussed on how to specify the scanning step voltages, and on how to adjust or maintain the optimum step voltages.
