Identifying National Semiconductor Analog ICs in Portable Headset Intercom Circuit

Can anybody tell me the part numbers of the National Semiconductors ICs shown on the attached picture?

The circuit is a small portable headset intercom with Squelch and Audio controls..

Thanks,

Hi there,

From the picture, you can already tell the part numbers of the IC. the one printed on top of the IC, like M8752..

Hi Kevin,

Thanks for your response to my question; but M8752 is not the part number (I've checked before at the TI webpage). It is like a serial or production batch number..

Best,

Emilio

There could be a number of issues here. How old is the unit, if obsolete by many years, then tracking a production number like those will be difficult. Chances are that if the parts were in current production, those numbers would have shown up in a web search.
The second number is often a production date, but that doesn't tie in either.
The chips may have been especially numbered for the units manufacturer if they purchased enough of them. Hard to know. With TI now owning Nat Semi, it will make it all the more difficult, most of the old hands at Nat Semi are probably long gone,
Cheers,
Richard

Thanks Richard,
Yes you're right the NS old-timers are long gone and those production numbers and production dates don't help at all..
BTW this unit is from the eighties...
Best,
Emilio