it looks as though it is intended to work at negative 9 volts. It will apparently tolerate, but not operate with, reversed 9-volt battery, though that may be a misprint, as it appears only once.

Probably the easiest way to "talk" to the thing is by using the old classic RS232 drivers and receivers, the MC1488 driver or equivalent and the MC1489 receiver. You can then set your ROM Vdd at the required ROM 0 volts and its Vss at the required ROM -9 volts. By setting the 5-volt logic you want to use somewhere in between, which you do by assigning the GND level of the MC 1488 drivers and MC1489 receivers appropriately, you will get "legal" 5-volt levels from the MC1489's. Another way to look at this is to set the logic GND at its GND, and supply +4.5 to the MC1488's Vcc and -4.5 to its Vee, while feeding the ROM's Vss the +4.5 and its Vdd the -4.5. The ROM will see levels that it interprets as either close to its Vdd or its Vss. Note that the RS232 drivers and receivers are inverters.

This speech ROM operates at a leisurely pace, so you can bit-bang the interface to the ROM pretty easily with an 805x type at a slow pace, but the timing requirements must still be met precisely.

Study the datasheet carefully ...

RE