OVERVIEW
The model 757 is a general purpose fast logic unit used to perform logic OR, AND, Fan-in, Fan-out, TTL to NIM level conversion, and polarity inversion. The 757 contains eight logic channels. Each logic section consists of two inputs which accept NIM or TTL signal levels. The inputs form a logical "OR" function and generate four NIM level and two complementary NIM level outputs. The AND function can be implemented with negative NIM complement logic levels. All input functions produce output widths equal to the overlap time of the inputs.
Sections are easily configured by means of a four position switch allowing the module to be setup as follows:
Logical
SectionsNumber
of InputsNormal NIM
OutputsComplement
NIM OutputsOctal (8)
2
4
2
Quad (4)
4
8
4
Dual (2)
8
16
8
Single (1)
16
32
16
The logical setup is easily determined by front panel LED's indicating which sections are logically linked. The input to output propagation is timed to within 500pSec for any configuration selected, allowing for precise timing without re-adjusting cable lengths for different logic setups.
The outputs are the current source type with two pairs of negative bridged outputs and two complements for each channel. When only one output of a bridged pair is used, a double-amplitude NIM pulse (-32mA) is generated, useful for driving long cables with narrow pulse widths. In addition, current source outputs also allow pulse clipping and provide inherent protection from damage due to shorted cables.