here are parts compatible with 7611's
256*4
+------+
A6 |1 16| Vcc
A5 |2 15| A7
A4 |3 14| CE2/
A3 |4 13| CE1/
A0 |5 12| O1
A1 |6 11| O2
A2 |7 10| O3
GND|8 9| O4
+------+
Signetics MMI TI Harris Raytheon AMD National Intel
--------- --- -- ------ -------- --- -------- -----
TS 82S129 (50ns) 6301-1 24S10 7611-5 29661 27S21 74S287 3621
82S129A(27ns) 63S141 - 7611A - 27S21A - -
Intersil Fujitsu
-------- -------
7052