'89 Firebird ECM PROM

[Terry Martin]

I got a ECM out of a '89 Firebird Trans Am GTA. I pulled the following
number out of the PROM by looking through the quartz window with a
microscope:

(M)1984 TI
 27C128A   ....could be 27C12HH, or some variation of the last two
digits. 

Question: Is this the right PROM for the ECM that's supposed to be in
this type of vehicle? I have not found a reference to the numbers that
would indicate it's a 8051 or 8065, etc. 

Alternatively, can someone confirm the manufacturer and # of the PROM?

Thanks much,
Terry