Bidirectional and non-bidir. parallel printer cables

Dear Folks

I'm trying to discover the pin connections for bidirectional and non-bidirectional parallel printer cables - DB25 to Centronics - I've found the IEEE1284 standard wiring, but nothing useful about non-bidirectional cables...
It's the cables themselves that I'm interested in, rather than the differences between LPT, SPP, EPP, ECP etc...
With thanks, Hugh.

 

Try this for pinouts of standard centronics vs. IEEE1284.

 

Hi again Zephyr

thanks for the link, pencil and paper time for a while! I'd trawled around quite a bit but inconclusively, lots of mutually contradictory stuff out there, I just want to be able to put a meter over the thing to prove it...

still not sure that it's the cause of the problems, though. Port's on the motherboard, can configure as LPT, ECP, EPP; the BIOS says "Autoconfigure" for it (this is on an Apricot), after trying to install an Epson (Stylus C62) printer, Windows Device Manager says the port is an EPSON LPT port ??? [I've not seen a printer name there before, quite startled me] - so I suppose that it got autoconfigured somehow ? never knew that could show a particular printer name, all I've ever seen in device manager before are things like "ECP Printer Port (LPT1) "

..trying to sort this out for a friend who's going scatty over it, and can't say I've much of a handle on it myself as yet!

Tried Lexmark printer, also won't work properly, even when set to disable bidirectional comms; but a good old Epson FX80 has no hassle with the same cable. So I started to suspect the cable isn't bi-directional enough, or the port itself - but I now hear that the same Lexmark printer *used* to work with the same cable on the smae port - so perhaps the next stage should be to force the BIOS to ECP for that port, thinking that the port's got reconfigured somehow?

Best Wishes as ever, Hugh

PS I did come across a bit of unidirectional copper wire once - well sort of, it was two bits touching, one was a bit corroded and I'd made a copper/copper oxide rectifier by mistake. 'twas between two wires in an address bus or something similar... most confusing.
ATB

 

Yes Hugh, I am quite familiar with naturally occuring diodes and have spent a great deal of time tracking them down with field strength meters. They can cause plenty of headaches in high power areas of RF fields and tend to cause TVI and RFI on frequencies that don't seem to be related to the fundamental being broadcast.

Best wishes and good luck with your printer challenge.

 

Dear Zephyr and all

well I got about as far as I could with pencil and paper, there was a link to "Cable Pinouts" as well, which looked like it should have been *really* useful but unfortunately was broken...

thinking about the fact that the Lexmark printer did once work on the same cable, but only if it was turned on *before* the PC (this is quite contrary to what's implied in the Lexmark documentation) - it really seems to be pointing to this BIOS "Autoconfigure" setting for the port.

Which has me puzzled, like, what changes it - well, presumably installing a printer changes it? (Perhaps, 'coz a printer might well want it as a ECP port but another peripheral might prefer an EPP...) so I'm going to see if I can set it to *stay* as an ECP using the BIOS, and then reinstall the printer.... It can't have been saying "EPSON LPT" for long as only just put W98 on from formatted HDD a few days ago. If I'd known it was going to end up like that I'd have watched it like a hawk to see when it changed, but - heck it's easy to be wise after the event.

Have just committed the ultimate sin - run out of coffee. Which has ground everything to a halt for a while - but will post again somewhen soon if I've got anywhere [!]

Thanks once again, Hugh.

___

Antique Compaq P1/100 No MMX, W98 not SE, 30GB+729MB, 3*486 all on Direct Cable / Interlnk, homebrew dataswitches, 1*8086 (yea), 4*EL34, 2*GZ34, 2*Ferrograph 5A, 6*cats (hungry) & 0*coffee.

 

Dear All
ahh, it was the port after all - which led me a merry dance in its own right - got the printer working fairly readily by going down that road, but kiboshed the display in the process - LPT1 had gone in at 0x3BC which must have had some sort of clash with the display driver or summat...
In the end I confused the BIOS into putting the port in as a bidirectional LPT2 but at 0x378 (!?!)(well the BIOS called it LPT2), which Windows and the printer then picked up on as LPT1 (!?!) - well at least the address was OK - unkiboshed the display & all is working now...
Phew, Hugh.

(now I have to (try to) fix the washing machine, which is attempting to defy gravity every time it spins... but at least we have coffee.)

 

Hugh

Thanks for the blow by blow and also the feedback of the final (we hope) results. Your experience closely parallels some of mine. I have a propensity to think that problems are more complex than they usually are. In reality, most computer problem are fairy simple and usually just take one small setting or adjustment somewhere. Finding where is what makes for the Iliads.

Good luck with the washing machine. Sounds like one of the springs that holds the drum may be unhooked but that's a problem for another forum I suppose.

Best regards.