29 Feb
2008
29 Feb
'08
4:01 p.m.
As said before, one can easily get some of the small (8 pin dip) micros to do
magic things, but sometimes (as mentioned) it is a bit more trouble than it is
worth. Many of us (me!) have stuff in their junk
boxes^H^H^H^H^H^H^H^H^H^Hclassic part archive that will do the task quite
easily. In my case, I obtained a nice Facit 4070 paper tape punch and made up
a simple interface adapter (it fit inside one of those 2x DB-25 scramble boxes)
to make it function using a PeeCee parallel port. Now if I desire to punch a
paper tape, all I do is a simple copy to the printer port and ...buzzzz... out
comes the tape. Thankfully the Facit 4070 had some power available on its
Somewhat surpisingly, when I wanted to do this, I just wrote a bit of
software to drive the PC port lines appropriately. It wasn't that
difficult :-)
DB-25, but I needed to play around with all the levels
(it used 6 volt levels).
In the end, all it took was a single 74LS00 to do the trick on changing the
strobes to conform.
I seem to rememebr that when I did it that way, I used a '74 D-type and a
quad gate package (I forget which).
A word of warning to anyone working on a 4070. The interface may not be
what you expect!. The 4070 has 2 edge connectors and PCBs in the bototm
of the unit. The top board, in evey case that I've seen, is the standard
Facit control logic/PSU, and has the interface you've been usign The
lower edge connector intercepts the interface signals between this board
and the DB25 on the back of the unit. Im _many_ cases there's a simple
jumper board in that slot, so you get the 'Facit parallel' interface on
the D25. But they certainly made a serial interface (RS232 and current
loop) to go there -- I have one. An IEEE-488 interface has been rumoured,
but I've not seen that. And HP badged this punch but put their own
interface i nthat slot, it inverts some of the signals, etc.
-tony