Heath H/Z 19 terminals

From: Dave Dameron <ddameron_at_earthlink.net>
Date: Wed Jan 20 19:07:14 1999

At 09:10 PM 1/19/99 -0500, you wrote:
>The keyboard encoder in the Heath H-19 terminals (also the Zenith Z-19)
was a National Semiconductor part. It was discontinued in late 1981 or 82,
while the terminal was still in production. Heath bought tens of thousands
of them in a "last time buy" both for ongoing production and for future
service. I don't know the current availability of this item from Heath
(Heath does still exist, and does sell SOME parts), but it hasn't been
available from National for a decade and a half. It WAS a generic part at
the time. Note that every H/Z - 89/90 has an imbedded H/Z-19 terminal and
therefore uses this part.
>
>I know all of this because for 5 years I was the Product Line Director for
the entire Heath/Zenith computer line.
>
>Barry Watzman
>
Thanks for this info. I looked in my H19 and the encoder chip is a National
MM5740AAC/N. Probably the generic part I tried was another coding than AAC,
why it didn't work. _Now_ I know that the "AAC" refers to a specific coding.

The associated ROM is a plastic part with only Heath's number on it.
-Dave
Received on Wed Jan 20 1999 - 19:07:14 GMT