Need help identifying some cable connectors and their use case

Question

• First up
  • I can't identify the connector on the left. The middle one is USB mini B and the right is USB micro B
  • I don't think it's any USB or HDMI connector
  • The other end is a regular USB Type A
  • 
• Second up
  • One end is a female parallel port and the other end is split into female VGA and male RJ11 connector
  • 
  • 
• Third up
  • Just a regular 25 pin parallel port extension?
  • What was it used for?
  • 
• Fourth up
  • I think this is a 36 pin to 25 pin parallel port adapter?
  • How does it add pins?
  • what was it used for?
  • 
• Fifth up
  • This absolute monstrosity
  • Appears to be a male 25 pin parallel port that splits to 2 female 25 pin parallel ports and then each of those has a VGA adapter on it
  • Was this used for dual screens?
  • 
  • 
• Sixth up
  • A male Molex(?) connector to two female VGA connectors
  • Used for dual screens?
  • 

Answer 1

1 is micro usb b, or mini usb b. https://www.cablestogo.com/learning/connector-guides/usb

2 I have a feeling it might of been for a 'fax printer' combined type unit. So the RJ-11 would go to a phone line, giving a printer (with serial connectivity if it needed a modem) phone capability.

3 - yes, extension cord, for things that are far away ;)

4 - the added pins are likely ground pins - so they can all terminate to the same point.

5 - That's not VGA, it's 9 Pin DSUB. It looks like it may of been for connecting to a printer, or some other kind of embedded device, but this is always going to be guess work.

6 - As answered in chat by Journey Man Geek, that is https://en.wikipedia.org/wiki/DMS-59. So yes, 2 monitors to a single port on a graphics card.

This is also a great resource for identifying ports: https://removeandreplace.com/2013/04/13/computer-ports-learn-the-name-and-location-of-the-connections-on-your-desktop-computer-or-laptop/

Answer 2

1. Is probably a proprietary USB connection, most likely for some early mobile phone or a digital camera. Before micro USB became commonplace, a lot of companies that made USB-connected peripherals used custom connectors on the device side, either so they could reuse the same connector for multiple purposes, or just to force users to buy cables through them. I think I've seen that shape and size before, but I don't remember where.

2. Not sure, I'd have to see how exactly it's wired. It might be a combined fax/printer unit as mentioned in another answer, it might be some kind of RS-232 splitter cable (that's a DE-9 connector, not a VGA connector BTW), or it may be some completely custom cable.

3. Is probably a straight-through extender cable. In theory, usable for any application requiring a longer cable with DB-25 connectors (not nessecarilly parallel, old RS-232 serial links, especially for terminal servers, would also use DB-25, albeit with reverse gender on the connectors relative to parallel connectors). However, there's no way to be certain without checking the wiring (if it's short, it might be a special adapter cable, like a null modem cable).

4. Is an IEEE 1284 parallel cable, with a DB-25 connector at one end, and a 36-pin micro ribbon connector (sometimes called a 'Centronics' connector after the company that developed the original version of the IEEE standard) on the other end. The different connectors were used for the same reason that USB conventionally used separate connectors for the host and the device. These were the norm for parallel printers for many years. I don't recall how the extra pins were connected (probably either grounded or left floating). A 50-pin version of the same micro-ribbon connector was used for both the original SCSI-1 standard, as well as for RJ21 connections in analog telephone systems (carrying 25 phone lines in one cable, mostly used at branch exchanges).

5. Is probably an RS-232 splitter. The old DB-25 RS-232 connectors mentioned above could be wired to have two serial links over the same connector, and such a cable would be needed to connect two devices with DE-9 connectors to such a port.

6. Is a proprietary video-card adapter cable. Some older small-form-factor video cards use the crazy looking connector (it's not Molex, but I'm not sure what the branding is) with all the pins as their only external connector, and then require an adapter like that to split out to individual video connections. I've never seen one that splits to two VGA connections myself, but I've seen ones that split to two DVI-I or a DVI-I and a VGA before.