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Printer port question

 
 
Robert Baer
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      06-16-2013
Jeff Strickland wrote:
>
> "Robert Baer" <(E-Mail Removed)> wrote in message
> news:QPSut.21954$(E-Mail Removed)...
>> According to the original IBM documentation viz IBM Technical
>> Reference First Edition August 1981 page D-34 Parallel Printer Adapter
>> schematic, the following pins of the DB-25 printer connector are
>> exclusively inputs:
>> pin 13 is +SLCT (select, high for "1")
>> pin 11 is +BUSY (busy, high for "1")
>> pin 12 is +PE (paper out, high for "1")
>> pin 10 is -ACK (acknowledge, low for "1"; eg: inverted logic)
>>
>> So, how come with computer NOT CONNECTED to anything (NO power at
>> all), one sees that pins 10, 11 and 12 are SHORTED TO GROUND?
>>
>> Please explain how a printer can possibly work with that condition.

>
>
>
> Why do you care what the parallel port is doing? They have not sold a
> parallel printer in almost a decade. Surely if you have a parallel
> printer, you deserve a new one for Father's Day.
>
>
>
>
>

I want to use the four lines for nybble input data reads.

 
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Robert Baer
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      06-16-2013
Paul wrote:
> Jeff Strickland wrote:
>>
>> "Robert Baer" <(E-Mail Removed)> wrote in message
>> news:Ch0vt.10034$(E-Mail Removed)...
>>> Jeff Strickland wrote:
>>>>
>>>> "Robert Baer" <(E-Mail Removed)> wrote in message
>>>> news:QPSut.21954$(E-Mail Removed)...
>>>>> According to the original IBM documentation viz IBM Technical
>>>>> Reference First Edition August 1981 page D-34 Parallel Printer Adapter
>>>>> schematic, the following pins of the DB-25 printer connector are
>>>>> exclusively inputs:
>>>>> pin 13 is +SLCT (select, high for "1")
>>>>> pin 11 is +BUSY (busy, high for "1")
>>>>> pin 12 is +PE (paper out, high for "1")
>>>>> pin 10 is -ACK (acknowledge, low for "1"; eg: inverted logic)
>>>>>
>>>>> So, how come with computer NOT CONNECTED to anything (NO power at
>>>>> all), one sees that pins 10, 11 and 12 are SHORTED TO GROUND?
>>>>>
>>>>> Please explain how a printer can possibly work with that condition.
>>>>
>>>>
>>>>
>>>> Because they are held high by the printer that's not there? The printer
>>>> pulls these lines high.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>> On the surface,that _might_ sound reasonable..
>>> Except.
>>> The schematic shows INPUTS to a TTL gate for each one.
>>> On TTL logic, an input must be pulled down (below 1.4V) for a low to
>>> be asserted; a floating input on a gate acts like a high.
>>>

>>
>>
>> If there is a gate array, then the gate is low until a printer comes
>> along to pull the inputs high when the condition becomes true. If the
>> printer is available, the select line goes high, if the printer is
>> busy, the busy line goes high, if whatever is happening, the line goes
>> high, or it goes low in the case of the not-logic.
>>
>> I don't understand the question. I really don't understand why you
>> think something is broken on a port that has not been used in any
>> current technology in the past 15 or 20 years. I guess that's not
>> true, I'm using a Brother MFC that is connected to the parallel port.
>> It could be connected to a USB port, but I'm running out and I had a
>> parallel cable laying around.

>
> People use printer ports for GPIO functions. For example,
> I have a JTAG programmer cable, that plugs into a parallel
> port, and needs a driver installed to gain access to the
> appropriate pins on the interface. And I don't think my
> adapter, works on the end of a USB to printer dongle either - it
> has to be a real parallel port. I use a PCI Express card
> with parallel port connector, to move the JTAG cable to
> my current machine. That's because parallel ports are
> out of style now, so you pay extra to get them. This is
> the card I'm using.
>
> http://www.startech.com/Cards-Adapte...PP-ECP~PEX1PLP
>
>
> That card uses OXPCIe952. Which apparently has more functions,
> than there are connectors on my card.
>
> http://www.plxtech.com/products/uart...ldocumentation
>
> Paul

Get almost the same thing for about $17 (while they last):
http://www.jameco.com/webapp/wcs/sto...gDrillDownView

 
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Paul
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      06-16-2013
Robert Baer wrote:
> Jeff Strickland wrote:
>>
>> "Robert Baer" <(E-Mail Removed)> wrote in message
>> news:QPSut.21954$(E-Mail Removed)...
>>> According to the original IBM documentation viz IBM Technical
>>> Reference First Edition August 1981 page D-34 Parallel Printer Adapter
>>> schematic, the following pins of the DB-25 printer connector are
>>> exclusively inputs:
>>> pin 13 is +SLCT (select, high for "1")
>>> pin 11 is +BUSY (busy, high for "1")
>>> pin 12 is +PE (paper out, high for "1")
>>> pin 10 is -ACK (acknowledge, low for "1"; eg: inverted logic)
>>>
>>> So, how come with computer NOT CONNECTED to anything (NO power at
>>> all), one sees that pins 10, 11 and 12 are SHORTED TO GROUND?
>>>
>>> Please explain how a printer can possibly work with that condition.

>>
>> Why do you care what the parallel port is doing? They have not sold a
>> parallel printer in almost a decade. Surely if you have a parallel
>> printer, you deserve a new one for Father's Day.
>>

> I want to use the four lines for nybble input data reads.
>


OK, as a confidence builder, do a lap of the pins, and tell
me *all* of the pins that read zero ohms. For example, here,
the D-34 has signal GND on 16, 19 thru 29, and 33.

http://www.interfacebus.com/Design_C...r_PinOuts.html

Even if you'd managed to mirror image the thing, the 19 thru 29 are
on the wrong row for that. And you're not likely to flip the thing the
other way, and mix the rows up, because the shell shape gives a hint.

Paul
 
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Robert Baer
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      06-17-2013
Paul wrote:
> Robert Baer wrote:
>> Jeff Strickland wrote:
>>>
>>> "Robert Baer" <(E-Mail Removed)> wrote in message
>>> news:QPSut.21954$(E-Mail Removed)...
>>>> According to the original IBM documentation viz IBM Technical
>>>> Reference First Edition August 1981 page D-34 Parallel Printer Adapter
>>>> schematic, the following pins of the DB-25 printer connector are
>>>> exclusively inputs:
>>>> pin 13 is +SLCT (select, high for "1")
>>>> pin 11 is +BUSY (busy, high for "1")
>>>> pin 12 is +PE (paper out, high for "1")
>>>> pin 10 is -ACK (acknowledge, low for "1"; eg: inverted logic)
>>>>
>>>> So, how come with computer NOT CONNECTED to anything (NO power at
>>>> all), one sees that pins 10, 11 and 12 are SHORTED TO GROUND?
>>>>
>>>> Please explain how a printer can possibly work with that condition.
>>>
>>> Why do you care what the parallel port is doing? They have not sold a
>>> parallel printer in almost a decade. Surely if you have a parallel
>>> printer, you deserve a new one for Father's Day.
>>>

>> I want to use the four lines for nybble input data reads.
>>

>
> OK, as a confidence builder, do a lap of the pins, and tell
> me *all* of the pins that read zero ohms. For example, here,
> the D-34 has signal GND on 16, 19 thru 29, and 33.
>
> http://www.interfacebus.com/Design_C...r_PinOuts.html
>
> Even if you'd managed to mirror image the thing, the 19 thru 29 are
> on the wrong row for that. And you're not likely to flip the thing the
> other way, and mix the rows up, because the shell shape gives a hint.
>
> Paul

Finally figured it out.
Had made a new cable with flat ribbon cable and an IDE connector or
the PC using a hand vice.
There is a goodly separation between the forked pin rows, and if the
cable is not aligned exactly right,the edge of one can (also) cut into
the next wire,giving a short when connector is plugged in.

 
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