4 bit even parity generator circuit

Contextual Info: » 111 1— — T'lS 2 -3 / 0*^1723 GD74't7fl 1 I T E X A S I N S T R -CLÔGIC3- SN74ALS29833, SN74ALS29834 8-BIT TO 9-BIT PARITY BUS TRANSCEIVERS D2990, FEBRUARY 1987-REVISED JULY 1987 Functionally Similar to AMD AM29833 and AM29834 SN74ALS' . . . DW OR NT PACKAGE