[sci.electronics] Hardwareless Centronics -> HPIB converter ?

inuy@vax5.cit.cornell.edu (09/12/90)

I have recentley been given a nice wide carrage printer that I would like to
use with my PC.  There is one small hitch with it though, it has an HPIB
interface.  After looking at the HPIB interface I got to thinking if I where to
turn the LISTEN ALWAYS switch on (this takes the printer out of addressed
device mode, and makes it print anything that comes over the bus) and connect
the 8 data lines from a noraml centronics interface to the 8 data lines in the
HPIB interface I may stand a chance of getting it to work as a centronics
printer with no additional hardware.  My remaining question though is what to
do with the strobe output from the computer on the centronics port.  This would
have to go to one of the control lines on the HPIB port, but which one?  Any
comments or ideas would be helpful!

Matthew Kleinmann

den@hpfinote.HP.COM (Don Novy) (09/14/90)

  Directly connecting the 8 Centronics data lines to an HP-IB (IEEE 488)
device will NOT work unless you change the software as the data must be
inverted. i.e. Centronics is logic 1 = 5V but HP-IB is logic 1 = 0V.

  I designed a simple circuit to do this that I use with my Atari 800XL. As I
recall, it uses 2 7414s, a 74123, and a 7474. I don't have the schematic handy,
but I could try to do it in ASCII characters if you're interested. Since you 
wanted a no hardware approach, however, I at least wanted to pass this info
along.

Don Novy
Hewlett-Packard
don_novy@fc.hp.com