Changes
/* Further Chips */
1 K555KP11 74LS257 8-to-4 data selector (D38=sheet1) (clock select)
1 K555KP12 74LS253 8-to-2 data selector (D26=sheet3)
1 K555LN2 74LS05 Hex inverters, OC (D76=sheet3)
5 K555TM2 74LS74 Dual flipflop (D40,D77,D66,D57=sheet1, D71=sheet3)