NEO-257

Quadruple 74HC257 2-to-1 multiplexer with common select line, making 16 switches in one chip. Used in dual slot MVS systems to select one of the two C ROM (and S ROM ?) buses.

Select signal comes from one of the "SLOT" outputs of NEO-F0 ?

Pinout

Information provided by Channelmaniac.

File:Neo-257 pinout.png

OpenOffice Draw file: File:Neo-257.odg

• A*,B*: Inputs
• Y*: Outputs
• Select: Output A if LOW, B if HIGH.
• Some pins marked as ground could be "enable" pins