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From: logajan@ns.network.com (John Logajan)
Newsgroups: comp.sys.atari.st
Subject: Re: Problem using HP II P  laserprinter  with 1040 ST
Message-ID: <1991Apr2.045130.24087@ns.network.com>
Date: 2 Apr 91 04:51:30 GMT
References: <1991Mar27.150249@kboeng.enet.dec.com> <16830011@col.hp.com>
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In article <16830011@col.hp.com> davea@col.hp.com (David E Allen) writes:
>> 6.) Install a PNP transistor in the STROBE line.
>>                           -----> Ground
>>                           !
>>                          / C
>>                      B !/
>> from Atari STROBE >----!
>>                        !\
>>                          \ E
>>                          !
>>                          ----------> to Printer STROBE
>
>Would just a diode work - connected in the STROBE line with cathode towards
>the Atari?

There is no amplification in a diode, and it has a forward voltage
drop anywhere from .3 to .8 volts.  This added to the low current drive
capability of the Atari strobe line puts the "0" voltage up into the
1.0 - 1.5 volt range.  I'm not sure if the HP requires TTL levels or
CMOS levels, but the minimum low of TTL is usually spec'd at 0.8 volts.
 
You could try it though.  If you drop bytes or your print routine hangs
often you'll have a good guess why. :-)

Besides, how hard it it to solder three wires instead of two (33% harder :-)


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