OT: Printer port question

Makes ZERO difference.

Ahh, but it aint; (old) printers work fine on same port.

Ahh..someone that knows how to think. After many hours, i finally found what caused the problem. I had made a cable for the printer port using some flat cable and an IDC type connector. There is a large gap between the pin row 1-13 and the pin row 14-25, and if you do not (a) keep the cable rather flat, and (b) at _exactly_ right angle to connector/pin alignment,then using a hand vice for assembly can give problems. All it takes is for the side of a connector fork to cut into the next wire and one can get a short, as ALL pins 19-25 are ground!!

That's fine if you're actually connecting a printer but they usually don't work with other parallel devices.

Devices that steal power from parallel port signal pins have been a nightmare as the parallel port has evolved from providing close to a 5V level on the signal pins to providing close to the minimum acceptable voltage levels on the signal pins. This change is for reasons related to the IEEE 1284 spec that weren't issues back in the days of the original Centronics port.

I was an apps engineer for National Semiconductor supporting SuperI/O devices with parallel ports and we occasionally got complaints from manufacturers of parallel port peripherals that stole power from signal pins because as we came out with parts that moved from the original SPP (standard parallel port) to IEEE 1284 EPP and ECP, their peripherals would no longer function. There was nothing we could do. Our parts met the IEEE specs and these manufacturers were doing things that they shouldn't have done to avoid the need for, and the expense of, a wall wart.

Actually the original parallel ports could communicate bi-directionally in nibble mode where four bits of data were sent back to the computer via the four input control lines.

A modern parallel port bears little relation to what's described int the IBM manuals. Termination networks as well as the parallel port chip disabling the inputs and outputs when the parallel port is not in use make attempts to use an ohm meter worthless in determining what is actually grounded.

On a sunny day (Sat, 15 Jun 2013 22:20:34 -0800) it happened Robert Baer wrote in :

(ethernet):

needed...

cable:

Zero is a bit vague, I once build a 'short tester' (to find shorts in for exampe PCBs) that could measure really low resistances, basicaly a variable curent source with some voltage sensor.

Sort of think there is a pull up in the parport inputs, that well may be a depletion MOSFET, that then will be on when power is off. So a few ohm perhaps? (Could be wrong about that), but those inputs are '1', and putting a multimeter to ground shows some currents in mA range IIRC?? mmm maybe it was something else I measured... LOL

But is not 25,24,23,...,18 ground? Sounds to me like you count the wrong way around... You are counting from pin 14!!! THEN pin 10 is ground! Check the numbers!

:-)

Unfortunately, the question is always what the working conditions were at the place where this was produced.

What? This is SED! You some kind of *communist* there Joerg?

:-)

Nah, most certainly not me. But we have to keep an eye on this stuff.

Still not a bi directional port, though. Microsoft's Interlink used that method to move data between computers. I used to install DOS & Windows 3.1 with a data cable and a boot floppy. That way the original MS disks were unopened when given to the customer with a new computer.

Yikes, that place (CDW) is crazy overpriced (far worse than yellow violets [flowers]) like all getout.

I can hardly believe that you could recommend them.

?-/

I landed some really good deals there. But to me, in a line stop situation, the main thing is who has stuff in stock.

AFAIUI, some of those places give kickbacks to IT consultants. That would be an intolerable conflict of interest for an engineer, but maybe not for a IT independent.

I doubt CDW would do that. Unless it's bulk purchase discounts which are totally legit IMHO. I bought some hard drives there, at prices that were very hard to beat.