[comp.sys.ibm.pc.hardware] Disabling Parallel Port by shorting pins?

timur@seas.gwu.edu (The Time Traveler) (02/13/91)

I want to disable the parallel port by making the computer think that it's
sending data.  I think that if you short two (or more) pins, then the
data-sent signal (or whatever it is) is always triggered, making the 
computer think that the byte it just sent was received, and it can send
the next one.  

Can anyone help me?

timd@hotwheel.dell.com (Tim Deagan) (02/13/91)

In article <2716@sparko.gwu.edu>, timur@seas.gwu.edu (The Time Traveler)
writes:
> I want to disable the parallel port by making the computer think that it's
> sending data.  I think that if you short two (or more) pins, then the
> data-sent signal (or whatever it is) is always triggered, making the 
> computer think that the byte it just sent was received, and it can send
> the next one.  
> 
> Can anyone help me?

Curious question.  Do you want the computer to not think the parallel
port is not present (rewrite the installed hardware status word at 40:10 to
clear bits 14-15 which represent the installed parallel adapters)?  Or do
you want to have the computer not hang when it writes data to a port with
nothing attatched (you could possibly try this:

	short pin 10 (ACK#) to pin 1 (STROBE#)
	short pin 15 (ERROR#) to pin 16 (INIT)

WARNING!!!!!!  I haven't actually tried this!!  It is based on my 
observation of the pinouts of the parallel port.  Submit this to 
general discussion before implementing, I will not assume responsibility
for frying your parallel port!  On the other hand, it should work. :-) )

I'm still not sure what it is you're really trying to do.  All parallel
ports are not the same, some are bidirectional, others are not.   It'll
be easier to prescribe a fix if the problem is stated clearer.
------------------------------------------------------------------------
------------------"Wake up!  Wake up!" - Spike Lee ---------------------
------------------------------------------------------------------------
                         Rev. Tim Deagan
                     timd@hotwheel.dell.com
                     timd@twaddle.dell.com

robin@uhunix1.uhcc.Hawaii.Edu (Robin Amano) (02/14/91)

In article <2716@sparko.gwu.edu> timur@seas.gwu.edu () writes:
>I want to disable the parallel port by making the computer think that it's
>sending data.  I think that if you short two (or more) pins, then the
>data-sent signal (or whatever it is) is always triggered, making the 
>computer think that the byte it just sent was received, and it can send
>the next one.  
>
>Can anyone help me?

For PC Technician you need a loop back plug to test the port.
Here is the jumpers you need to make the male db25 connector.

 5-|
15-|

 6-|
13-|

 7-|
12-|

 8-|
10-|

 9-|
11-|

One customer had a xt compatible portable and needed to demo a sales
package.  He wanted to run the program without a printer, so to fake
out the computer we came up with this:

GND pins 11 & 12  or:

11-|
25-|

12-|
24-|

Hope this helps.


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