he 74S288 type bipolar PROM (32 words x 8 bits) was very common in the 1970's up until about 1985. Similar chips with the same pin-out and functionality were supplied by many manufacturers. A few equivalent part numbers are shown below. Any of these devices might appear in your CCPU board. The BX288 will replace any of the following parts. 
74S288 (National Semiconductor) equivalent devices:

AM27S19, AM27S09, AM27LS09        AMD
7112, MB7051                      Fujitsu
7603-5, HM7603                    Harris
5610                              Intersil
6331-1, 63S081                    MMI
82S123                            Signetics
18S030, SN54/74S288               Texas Instruments (TI) 


The 74S287 type bipolar PROM (256 words x 4 bits) was very common in the 1970's up until about 1985. Similar chips with the same pin-out and functionality were supplied by many manufacturers. A few equivalent part numbers are shown below. Any of these devices might appear in your CCPU board. The BX287 will replace any of the following parts.

            74S287 (National Semiconductor) equivalent devices:
            AM27S21, AM27S11               AMD
            93427, 93467                   Fairchild
            MB7052, 7114                   Fujitsu
            7611-5, HM7611                 Harris
            3621                           Intel
            IM5623A                        Intersil
            6301-1, 63S141J, 5201?, 6201?  MMI
            82S129                         Signetics
            24S10, 34S10,SN54/74S287       TI
            29661                          Raytheon
            DM7574/8574, DM7597/8597       National