[GreenKeys] IC help

[Keelan Lightfoot]

Jack,

http://www.datasheetarchive.com/MM5220-datasheet.html

- Keelan

On 2012-09-03, at 4:41 PM, Jack wrote:

> 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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