NEO-253

Package	QFP64R
Manufacturer
First use	1992 ?
Used on	SLOT4F

Quintuple 74HC253 4-to-1 multiplexers with common select lines, making ten 4-to-1 switches in one chip. Used to switch read-only buses. The inputs are named according to the related slot: A is slot #1, B is slot #2...

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

Cartridge wait cycle configuration and Z80 bus.

• Mux 1: PWAIT0
• Mux 2: PWAIT1
• Mux 10~3: SDD7~SDD0

Outputs go to CN9.

SLOT4F @ 5D

Sprites and fix layer graphics.

• Mux 1: CR30
• Mux 2: CR31
• Mux 10~3: FIXD7~FIXD0

SLOT4F @ 5C

Sprite graphics.

• Mux 10~1: CR29~CR20

SLOT4F @ 5B

Sprite graphics.

• Mux 10~1: CR19~CR10

SLOT4F @ 5A

Sprite graphics.

• Mux 10~1: CR9~CR0