Path: utzoo!attcan!uunet!cs.utexas.edu!sdd.hp.com!zaphod.mps.ohio-state.edu!brutus.cs.uiuc.edu!ux1.cso.uiuc.edu!uxa.cso.uiuc.edu!mjw06513
From: mjw06513@uxa.cso.uiuc.edu (Mary Winters)
Newsgroups: comp.sys.ibm.pc
Subject: Re: INPUT PARALLEL DATA OVER THE PRINTER PORT?
Message-ID: <1990May30.153755.29766@ux1.cso.uiuc.edu>
Date: 30 May 90 15:37:55 GMT
References: <12548@netcom.UUCP> <3260@galena2.UUCP> <7730@canterbury.ac.nz>
Sender: usenet@ux1.cso.uiuc.edu (News)
Organization: University of Illinois at Urbana
Lines: 31

In article <7730@canterbury.ac.nz> CHEM194@canterbury.ac.nz (J.DAVIS) writes:
>well, I'm sitting here looking at a PC technical ( hardware ) reference,
>and this is what it's got to say
>
>"output to address 03bch ( for mono graphics/printer adaptor ) or
>                   0378h ( for printer card )
> 
> this instruction captures the data from the data bus and sends it
> to the respective ( data ) pins on the printer adaptor. i.e bits
> 0-7 on pins 2-9 respectively "
>
>"input from address 03bch ( for mono graphics/printer adaptor ) or
>                    0378h ( for printer card )
> 
> this instruction gets data from the pins on the adaptor on to
> the data bus in a similar way to the out instruction on the 
> dame adress"
> 
>Sure looks like fully bi-directional 8-bit to me ....

It might at first glance, but if you actually try it, you'll find that you'll
only be able to read the value last written to that register, not the value of
some external signal applied to the output lines. That is, unless you remove
the ground connection on pin 1 of U4 and tie this pin to +5V, thereby
converting the output port into an input port.



--
uv@f69.n233.z1.fidonet.org
Suffering from PMS (Presentation Manager Syndrome)