NEO-253

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NEO-253 chip found on a SLOT4F board.

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 NEO-273.

Pinout

OpenOffice Draw file: File:Neo-253.odg

Select signals come from NEO-F0 SLOTA and SLOTB.

SLOT4F @ 5E

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

SLOT4F @ 5D

SLOT4F @ 5C

SLOT4F @ 5B

SLOT4F @ 5A

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