14 Dec
2015
14 Dec
'15
6:58 p.m.
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.
--Chuck