8-bit PIC made on 700nm UV EPROM process but in non-windowed (OTP) package. Contains a MCU die (512 12-bit EPROM words for firmware plus 25 bytes RAM) and a 16-byte 24LC00 I2C EEPROM die for data storage.
TODO: Better stitch
Looks like 2-metal CMOS at around the 800nm node.
Die markings:
Center left
(Microchip logo) MICROCHIP (M) 1996 74AK2
Upper right
74AK2
Bottom center mask rev markings, partially obscured by dirt
?? ?? 30 40 50 10 ?? ?? A1 A1 A1 A1