Most likely a standard 4 KiBit 512 by 8 Bipolar PROM.
Going from pinout and assumed DIP 20 it's either an
- AMD 27S28 (OC output), or
- AMD 27S29 (Tristate output)
From the circuit shown I'd assume it being a 27S29. Timing wise both are the same.
Compatible types for AM27S29 (AM27S28) are
- Harris HM7649 (HM7648)
- Monolitics Memories MM53/6349 (MM53/6348)
- National DM74S472 (74S473)
- Signetics S82S147 (S82S146)
- Texas Instruments SN74S472 (SN74S473)
I wouldn't get confused by different (inverse) logical address/data numbering, as that works fine as long as the programming file is coded accordingly.