A FASTBUS TDC System

A new time digitizing system is developed for use in new large scale drift chambers of colliding beam experiments at TRISTAN. The system is based upon 64-channel single-hit time-to-amplitude converter(TAC) modules with analog multiplexers and a Scan ADC (SADC). Up to 1536 TAC channels in a FASTBUS crate are scanned and AD converted by a SADC in the same crate. Hardware data processings such as pedestal and slope corrections (Ax+B), address conversions, sparse data scanning and test hit-pattern loading are available.