[GreenKeys] IC help

[Jack]

ZCZC

 

I have two TTY test sets that have a

National Semiconductor MM5220BL/N 24 pin IC in them.

I believe it's a read-only-memory that either converts

Baudot to ASCII or contains the FOX message (or both).

One test set is a 5-to-8 level converter from an old Bell

gadget and the other is a FOX test set that seems to have

a diode matrix along with the NS chip. 

 

I'd like to know the pin-outs for this chip, but it's nowhere to

be found on the Internet. Does anyone have any ideas or

old NS manuals? One chip has a 1976 date code.

 

TNX,

 

Jack K0TTY

 

NNNN

 

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