Mystery IC: Allen Bradley 314B102

Chuck Guzis cclist at
Mon Dec 14 20:58:11 CST 2015

On 12/14/2015 06:15 PM, Fred Cisin wrote:

> I got in late.  My first encounter with Centronics was TRS80 (1979?)
> At that time, Centronics did not yet have a monopoly on parallel
> "protocols", although the company had certainly been around for a
> while. Once they got the TRS80 market, and then the IBM PC market,
> any other designs faded away fast.

The other common interface was the Dataproducts--IMOHO, a much better 
one.  The usual DP connector was a 4-row job (I don't know what the 
connector part number was), but DC-37 was also an option.

I think DP used 220/330 termination on lines, where Centronics was a 
simple 1K pullup.  There were also differences in signalling--DP has 
both "ready" and and "online" signals.

When I first encountered the Centronics, I thought that it required OC 
drivers, but apparently totem-pole was good enough for IBM, something 
which surprised me.

Most medium-sized line printers around 1980 could be configured for 
either interface.  Otherwise, converters could be purchased inexpensively.


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