What kind of display is this?

[Dave92F1]

See this ebay listing: https://www.ebay.com/itm/225986603289

It claims this is a "IBM 3090 Mainframe Disk Test panel" (if so, from the 1980s).

The display at the top left (says "FEDCBA, 111111, FEDCBA, 222222") is really odd. What kind of display is it?

Look at the back pic - you can read one column as F 1 F 2 (upside down).

[coromonadalix]

at first i would have said some dot matrix display with engravings in them ?

you do have some manuals

http://vtda.org/docs/computing/IBM/Mainframe/Hardware/System/SA22-7121-6_3090ProcComplexFunctionalCharacteristics.pdf

[PA0PBZ]

The " FEDCBA" sequence can also be seen on the switch. Here is another one:  https://www.ebay.com/itm/154837559445
I wonder if it is a display or some kind of patch panel where the characters are plugged in?

[pcprogrammer]

Intriguing. Have never seen one in my life, but to be fair those computers are probably older then me.

Close up examination might reveal what it is and how it works, but not going to happen with those prices. 

[Haenk]

Another one of those:

https://www.ebay.com/itm/154837559445

Shows the cards, that are plugged into the "displays" - and one additional card, which is missing in this offer.
I would say that's just some small bulbs behind the visible (in the second offer) lettering, so nothing fancy.

Also, this allows dating: 5.78 QUAL-TRONIX

Also interesting: https://www.darlingfischer.com/obituaries/Frank-John-Casale?obId=29178773

[lokin4areason]

https://americanhistory.si.edu/collections/object/nmah_334285

that setup looks old enough to test one of these puppies

they have some number(s) on the device , but i dont know if it ll reveal at what it may be

[Dave92F1]

The " FEDCBA" sequence can also be seen on the switch. Here is another one:  https://www.ebay.com/itm/154837559445
I wonder if it is a display or some kind of patch panel where the characters are plugged in?

Ya, that's my question - is it really a display (that can be changed dynamically) or just some kind of static labelling (maybe attached to each plug-in card)?

That other ebay listing shows more and better pictures, including a label that says "QUAL-TRONIX ASM#2200545 E.C. 426283 DATE: 5-78".

Googling on "qual-tronix display" led me to this: https://www.vintagecomputer.net/ibm/1800/scp/

There's pictures there that look very similar, including another QUAL-TRONIX label: https://www.vintagecomputer.net/ibm/1800/scp/IBM360_SCP_PWR-label.jpg

According to that site we're looking at "flip chips" (just from the filename): https://www.vintagecomputer.net/ibm/1800/scp/IBM360_SCP_flip-chip-rows-7.JPG

[Someone]

Ya, that's my question - is it really a display (that can be changed dynamically) or just some kind of static labelling (maybe attached to each plug-in card)?

My guess is that (possibly a subset of) the whole characters can be turned on and off to indicate... something (such as tracks or channels).

Like a fixed function LCD display.

[coppice]

I'm pretty sure that isn't for a 3090. The 3090 is a 1980s design, and that panel is certainly much older. It looks more like it belongs with the original IBM 360 in the early 60s. I seem to remember similar formed character hexadecimal displays on the front panel of some 1960s IBM kit.

[HarryDoPECC]

Looks to me like a label on each connector. Characters dodge the pin positions.  Same labels visible on the inside view too.