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Strange computer problem loosing hardware lpt2 port

Being not really a newby this i can say is the stranged problem i ever have seen
I have in a company a POS (point of sale) installed working for about 2 years without major problems
The computer used is a HP verctra (DOS 6.22) with 3 hardware parallel ports used as LPT1 LPT2 LPT3
On LPT2 is a small printer installed and is looped to the pay-desk drawer
Around 2200 in the evening now allready 3 times on a saterday but sometimes also on other days this LPT2 stop to work
I go there (lpt2 doesnt do anything anymore) eg Echo hello > LPT2 but if i change everything to LPT1 (in the software not changing any cables) everything is working again and than the strange thing the next day the LPT2 port is working again
I changed allready the extension card for the LPT2 and 3 and changed the printer but this didnt solve the problem
So for my feeling there has to be something happening around 2200 but I have no idees anymore
Somebody want to give it a try

Thanks Dan
Danny Kon
Danny Kon
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1 Solution
There is a virus on your computer that changes your current settings... You can install anti-virus sofware like spybot, adware and others...
Wow... Let me dust off my DOS hat and put it on.

Try this Parallel Port Detection and Test Utility to see if you can shed a little more light on the problem.
This is a very handy set of DOS utilities which you can use to check your standard parallel port addresses for parallel ports -- And to test how fast they are. It also can test them to verify if they appear to be working correctly.
It reports the I/O Address (3BCh, 378h, 278h), IRQ (5 or 7), and Port Type (Standard 4-bit, 8-bit bi-directional, EPP, or ECP). It also reports what DOS thinks the LPT port is set to. And with a simple paper clip loop-back connection, can test to see if the IRQs (interrupts) are working on your parallel ports.  

There is also a very valuable and extensive document about parallel ports included (PARALLEL.DOC) which is an excellent tutorial on parallel ports.

Danny KonAuthor Commented:
q-2000 impossible this is a cash register without connection to the internet also no additional software installed, the system is running MS-DOS 6.22 (Spybot, adware etc  1 are not for virus but for Spyware and adware 2 are for windows )

Randoker I have a loopback adaptor where I connect this to the LPT ports runs a external test on the ports as i stated before
When the error occure LPT2 = LPT1
LPT2 is not working anymore doesnt give me any responce also doesnt show any IRQ information  
So it seems that the LPT1 is dead and LPT2 is getting LPT1

Danny KonAuthor Commented:

So the problem had to do with electricity but your answer was in the good direction.


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