4-16   Theory of Operation 
4.2.5  µP Control 
 
Control between the microprocessor and the main board is accomplished via the 
RPM.  The RPM functions are: 
 
• Processor interface 
• MAM interface 
•  8 bit bus interface (MTB411, MCG426, MST429A, IIC) 
• Serial interface 
• Min-Max Computation 
• Histogram 
•  RPM is configured at boot up by the processor.  The RPM configuration program 
is stored in the flash memory. 
 
4.2.6 Trigger
 
 
  The different trigger couplings are : 
 
• DC 
•  AC   : cut off frequency is almost 7.5 Hz. 
•  LF REJ  : single pole high pass filter with a cut off frequency at 50 
    kHz. 
•  HF REJ  : single pole low pass filter with a cut off frequency at 50 kHz. 
•  HF  : frequency divider by four. 
  
 
Analog Controls 
 
A sample and hold fed by the precision DAC provides the threshold levels. A 
precision DAC is also used for a successive approximation ADC which measures 
Probus inputs, temperature, etc. 
 
   
4.2.7  Analog to Digital Converter 
 
  Introduction  
 
  The analog to digital converter system does the signal conversion to 8 bits, using  
  the following circuits: 
   
•  HSY632: Hybrid switching AMP 2 in 4 out.  
•  HAM631: Hybrid ADC 1GS/s with 4Mb memory.  Provide 83 MHz clock for 
memory and refresh for DRAM