Making a Printer Cable

[glurk]

I'm sort-of cross posting, but I think this is the best place to ask.  I have a floppy drive, a Percom AT88-S1PD (for Atari).  And it has a printer interface built-in.  The interface is exposed as a 34-pin male header (with one pin missing).  As originally sold, it came with a ribbon cable that goes to a Centronics connector.  I don't have one.

 

This is where I need help.  Is this a "standard?"  I don't know it.  Obviously, with the pin header 34 (really 33) pins, and the Centronics crimp-on being 36 pins, something is left unconnected.  And the connectors are not cheap, and I don't know how to make one.  Plus, haha, my vision is really bad.  So I can't easily count off the little wires.

 

I'm sure this is a matter of just crimping on the ends, but where does Pin 1 connect on the Centronics end?  Or, alternately, can I just buy a ready made cable?  I ALREADY have like 20 feet of the ribbon cable, and I have the floppy-style IDC connectors, I'd only need to get the Centronics end.

 

Any help (or pictures) of how to make the proper cable would be greatly appreciated!

 

[+OLD CS1]

We used to get the parallel port cables in packs for motherboards.  Some manufacturers were bastards, like no-name TX chipset mobos our boss used to pick up, and would make a couple of pin swaps so you have to buy their cables.  Otherwise, most boards like DFI, Soyo, Epic, ASUS, &c. used the same cables.  I am sure someone around here has a specimen they can show with the hood off -- I have a couple I would have to pull from systems.  I am almost as certain you can find pics or pinouts if your search fu is good.

[glurk]

I found a cable for sale, looks like this:

Except, that's the wrong gender on the Centronics end.  I'd rather make my own, I guess, to use up cable I already have, but am unsure where Pin 1 should go on the (male) Centronics end.  I'd rather "do it right" the first time, but I'm just unsure of how to do that!

 

EDIT: The problem is, if I do it wrong, those crimp-on connectors are nearly impossible to remove and do over.  I've done that before, but they usually break.

 

Edited September 30, 2021 by glurk

[carlsson]

Where will you connect the Centronics end? From what I remember, the printer end had those connectors, and the computer obviously had DB25. Like OLD CS1 wrote, (no, he didn't) there were parallel port floppy drives, but then I would assume you want a DB25 instead of a Centronics connector? Or is this some kind of printer interface that lets you insert a floppy disk, the drive automatically boots, finds an image file and sends it to a printer connected directly to the drive, without a computer inbetween?

Edited September 30, 2021 by carlsson

[glurk]

The back of the drive looks like:

 

Those 34 pins are the printer interface.  So I guess I need a ribbon cable with a 34-pin female on one end, and a MALE Centronics on the other end, that will attach to a printer.  The cable I posted above has a FEMALE Centronics, which is opposite of what I need.

 

And I guess with 34/36 pins, there are only 3 possible ways to crimp it, aligned fully left, aligned fully right, or centered on the Centronics end.  Unless there is some need to flip part of the cable, or jumper pins, or any nonsense like that.  I guess I was just hoping that someone had actually USED this printer interface before, and had a cable.

 

A picture of a working cable is all I really need, I suppose.  I'm just not sure of the connections, and my vision is just so bad anymore, I can't easily count the wires and trace them, etc.  I'm sure it's just a straightforward thing, I just wanted to get it right and not waste a connector - which I don't even have yet, I'll have to order one.

 

[carlsson]

Aha, now I understand. This is an Atari 8-bit floppy drive that has a built-in Centronics interface so you can connect a printer to it, and from the Atari side issue commands on the SIO bus that the drive will intercept and feed to the printer.

[glurk]

Correct.  And I just need a cable for it, or instructions / picture of a working one to "copy."

 

I don't want to screw it up and waste 1 or more connectors, or do something stupid like run 5v to ground or something.  This 34-pin to Centronics probably IS a standard of some kind, just an old forgotten standard that I'm not familiar with.

 

[+OLD CS1]

Ah, horse of a different color.  Ignore me.

[carlsson]

By the way, I found a bunch of manuals over at archive.org but none of them mentioned the printer interface as far as I could see. However I read about it elsewhere and got conflicting details whether it is the pin header or the card edge connector that is used for printer. The other one is used for daisy chaining extra Percom floppy drives, 2-3 wires per drive. I did find a schematic on Imgur but could not make much out of it. I saw that you raised the question in the Atari 8-bit section as well. Hopefully someone has additional pointers besides the manuals.

[glurk]

Yeah, I tried to research before I even posted.  Between conflicting information, wrong information, and none at all....  Not only are these drives rather scarce, finding a person who has actually used the printer interface seems even more so.  I'm sure I'll figure it out eventually - I still have to order the Centronics connector - or several.

 

I was just hoping to do this the "easy" way and not have to try to trace out wires or anything!

 

[carlsson]

Perhaps it could become your RetroChallenge for October?

[+OLD CS1]

5 hours ago, carlsson said:

Perhaps it could become your RetroChallenge for October?

For many of us, the most challenging aspect of this challenge is documentation.

[tep392]

This post is a bit old, but thought I should document what I have found regarding the 34 pin AT88-S1PD connector.  I'll be purchasing an 825 printer and have been investigating how I would connect it the printer interface on my AT88-S1PD.  This is the pinout I've been able to put together based on this schematic .

 

I think what I am going to do is build a short cable to go from this 34 pin connector to the 15pin connector on the CX86 cable, which will then plug into the 825 printer. I'll post back later if this actually works.

 

1	- strobe	2	- fault
3	- d0	4	- gnd
5	- d1	6	- gnd
7	- d2	8	- gnd
9	- d3	10	- gnd
11	- d4	12	- gnd
13	- d5	14	- gnd
15	- d6	16	- gnd
17	- d7	18
19		20
21	- busy	22
23		24
25		26
27		28
29		30
31	- gnd	32	- no pin
33		34

[tep392]

To address Glurk's original question, I did a little testing on my AT88 and I think a ribbon cable from the 40pin connector on AT88-S1PD to Centronics 36 connector should work.  The pin outs match except for the fault signal on pin2 of the AT88.  It's pin 32 on the Centronics connector.  The fault signal in the Centronics standard is also active low,  but in my testing of the AT88, fault needs to be held low.  I get an error 138 if it's high.  The cable that Glurk found would ground pin2 since that is the strobe ground on the printer side, so it would likely work.

 

I know this is an old topic, but I just wanted to document my findings.