NEO-253



Quintuple 74HC253 4-to-1 multiplexers with common select lines, making 10 switches in one chip.

Only (?) used on second revision 4-slot MVS systems. Not to be confused with the more common.

=Pinout=



OpenOffice Draw file:

Select signals come from SLOTA and SLOTB.

Todo: 10 and 42 are GND

SLOT4F @ 5E

 * Mux 10~3: SDD7~SDD0
 * Mux 2: PWAIT1
 * Mux 1: PWAIT0
 * Outputs go to CN9