This was before laptops generally had a built in 100BaseTX port and RJ45 jack, there were a lot of PCMCIA type II cards with stupid dongles that were easy to break or lose. Once laptops generally started having two stacked type II slots (two type II slots = single type III slot), it was possible to put a real RJ45 jack in them. Some versions came with dialup modem also, if I remember right they were close to $250 new...
As for "HDD on expansion card", traditional IDE is nothing more than ISA bus on cable with smaller number of address lines and pins that were assumed to be not needed omitted. Pre-DMA IDE controller consists of not much more than address decoder.
Have to put in a quick mention that the Microsoft Sidewinder 3D Pro is probably the worst piece of hardware ever made. Or at least my copy was. Never worked right, and one of the few pieces of hardware I've ever taken out to the dumpster at my old apartment(so this is like 12-14 years ago!) and summarily destroyed by stamping it into pieces, Office Space-style.
This little device was perfect back in the days of Novell Netware servers running IPX.
To install windows 95 or NT4 was a godawful number of disks. If you did have those, you also had to have the proper NIC drivers on hand as well to get it connected, and there were many different NIC's in our lot - far too many to carry drivers with you. And no USB and zip disks were far too faulty to rely on.
To add the Novell IPX protocol stack - it was a 6 floppy disk endeavor. Disk drives were slow - very slow... It would take hours to complete, and often the disks would not properly read.
I think it was an anti-piracy measure - the Novell installer would fail at the final disk of 6, and it would not find a particular file - the Novell installer floppies were over-provisioned so they were larger than regular floppies. This would make it impossible to copy.
But - using one of these Xircom adapters, with 3 disks we could boot DOS, install Xircom drivers, add TCP/IP and SMB, mount and format the local hard drive, and finally copy the Windows installer files and all possible drivers at once to the local drive. Run setup.exe; in half an hour you had a complete workstation on the network.
Hah! For the longest time I had one of those bouncing around in the bottom of my bed stand drawer. Once I realized that I didn't have a 5.25" floppy drive to read the driver, or a parallel port on any computer I owned to drive it, I tossed it out. These days however it would be interesting as a hack to write an driver for it for a small ARM chip (like the M0 or M0+). Get your 10 megabit tastyness :-) Oh and the SPI port runs faster than that buy hey ethernet right?!
I had one of these back in the day and even attempted to write a Linux kernel driver for it. All I can say is bletch, I was glad to get rid of it.
Very surprising that it works with a PCJr however. The PCJr was different from the PC in that it had a split address space. Many PC programs - particularly ones that banged on the metal wouldn't work without porting effort.
Amazing that these never supported Linux. I remember people tried to reverse engineer them but the project ran out of steam. I guess xircom felt their business was so strong they needn't cater to a bunch of hippies.
I just gifted one of these (though not branded Xircom, the design was exactly the same) to http://www.acms.org.au/ .. I took high resolution photos before donating, which I'll get them up on Wikipedia soon. I received it with DOS packet drivers on an old Epson 386 laptop, which would have been one of the first truly portable x86 machines. Unfortunately though the machine booted, this year the LCD screen had chemically degraded to the point where it was unviewable, so the machine no longer functions. It worked fine a few years back. Someone did get a Linux driver working for this one, apparently.
My best friend in high school gave me one of these as a birthday present, fairly sure I've still got it somewhere though the rubber ribbon for screwing it down (which was a very cool addition) broke at some point.
https://www.google.com/search?q=xircom+realport&num=100&clie...
This was before laptops generally had a built in 100BaseTX port and RJ45 jack, there were a lot of PCMCIA type II cards with stupid dongles that were easy to break or lose. Once laptops generally started having two stacked type II slots (two type II slots = single type III slot), it was possible to put a real RJ45 jack in them. Some versions came with dialup modem also, if I remember right they were close to $250 new...