The effective impossibility of creating multiple virtual 8086 was demolished for the most part with the release of the i386 processor. The 386 (and all successors, such as the 486 and the Pentium) contained within the chip specification a V8086 mode which implied that multiple 8086 process support was a design feature of the product. Fresh on the heals of the release of the 386, Digital Research released 'Concurrent Dos 3.0' in late 1989. The operating system ran in the protected mode, but allowed in a round robin fashion multiple virtual 8086 processes to run on a time slicing basis. The operating system was both multi-tasking and multi-user in that the multiple dos sessions could be allocated with more than one task to each physical users. The classic console would support up to 4 virtual sessions side by side (with hot key switching among them, and up to 2 sessions were allowed on serial terminals which could be attached to serial ports.
Better yet, CDOS 3.0 supported both the CP/M 86 API to allow legacy CPM 86 software to run, but also supported the MSDOS API, which though less robust was much in demand because native mode CP/M software was about as common as native mode OS/2 software is today. I stayed with the 8 bit systems throughout the 1980's. The IBM PC in its early vintages simply didn't do anything that my heavy Z80 based systems would not do. The first 8088 based systems were running at 4.3 MHz and my Z80 had 4 MHz. I had 1.2 megabytes on the 8 inch floppy and the PC had 360k. the situation was scarcely changed with the AT class machines with the i286. they featured 6 MHz and a 1.2m floppy which was some better but not a lot. Hard drives were becoming affordable but they were the 5 and 10 megabyte kind in the beginning which really didn't do much for me. My heavy system had a 4 of the 1.2m 8 inch floppies which was far more flexible than a small fixed drive because I could change disks.
As the decade of the 1980s rolled to a close, however, things were changing. I bought a NEC laptop so I could learn something about DOS, and in 1989 I became a Gateway customer. Back then they were recovering from an 'over clocking scandal' which involved them buying lower speed CPU's and over clocking them to boost performance. They had stopped that by the time I ordered my first system from them. I got a genuine 386-25 Ten years later I am still using the case, but not much else. I will never forget the specs. it was a monster at the time. The sturdy steel case could hold a full sized At motherboard (and they were full sized then and 3 full high or 6 half high 5.25" drives. By then we were in transition from 1.2k (AT class) floppies to the new 3.5" floppy drives and this fully equipped computer came with both floppy drives, though for a good many years I used the 5.25" floppies because they were much less expensive. It was also the boot drive. The motherboard was a full sized AT board, and Gateway blessed the system with an astounding 150 Megabyte ESDI full height hard drive. The generic hard drives of the day were of an MFM interface, but the ESDI was an upscale fast alternative to SCSI.
Installed cards include a drive controller card which supported the ESDI drive as well as the floppies. There was an I/O card for the serial and parallel ports, and an Orchid SVGA card. EGA had been the standard before this, but VGA had just come out and was suppose to be better, and I paid a little extra to get Super VGA. All totaled up with the SVGA option which got me a NEC 2a monitor instead of the standard VGA only monitor, the system complete with 4 megabytes of RAM was about $4,500.00. I installed Concurrent Dos 3.0 and put a WYSE 60 dumb terminal on each serial port, and I had the hottest thing on wheels. It was a 3 user system that worked much quicker than the old MPM II system on floppies that I retired.
One of the nice things about the Gateway was that it was made of generic parts which made for easy upgrades, something I really was going to need. It wasn't long before we began using up all of the 4 megs of RAM by loading multiple Dos applications, but that was manageable because the large motherboard would take more RAM. DRAMS in the Early 1990's had progressed to 1 meg chips. You bought the little centipedes in sets of 9 for a megabyte. Many systems were shipping with just 1 megabyte total when I bought this system from Gateway, but it had 4 megabytes installed and room on the motherboard for a total of 8 megabytes. DRAMS were dropping fairly rapidly even in those days, and when it got down to about $10 a chip I bought 36 of the little puppies and plugged them in upgrading my system to an astonishing 8 megabytes.
I liked this so well that I kept going. The rest of the office was still using the Radio shacks z80 systems, though I was able along the way to buy some of them with hard drives and they were clearly legacy systems now. The next go around was for an 8 port serial card. You had a choice here. The cheap generic cards used an interrupt (usually taking over one of the IRQ's associated with your regular COM ports, and provided you with 8 serial ports which were usable by concurrent Dos. There were also the more expensive 'smart cards' which did not use an IRQ and were instead memory mapped but It took an OEM version of concurrent dos for them to work and that I didn't have. The 8 serial ports supported speeds to 38.4k and could be either printer or terminal ports. Soon I was adding more terminals, and I was out of memory again.
the memory upgrade was harder but not impossible. There was a special reserved slot on the motherboard for a full length memory expansion card. This card would take an additional 8 megabytes of DRAM in a total of 72 sockets and suddenly I had an astounding 16 megabyte system. I got to 6 or 7 users, and I also managed to find some performance issues. the I386-25 just didn't have the horsepower for 6 users. But then there were 486-33 boards around so who cared.
The i486 integrated the 'coprocessor' into the processor and provided more horsepower so who cared about a 386 at that point. Not me. I got a 486 motherboard and put it in my Gateway case which is the end of the 386 story. My records aren't good enough to tell you just when the 386 was retired, but the 486 was having its day in the sun during 1993 and 1994. I still hade performance issues with the 486-33, and I do know that I left the 486 for a Pentium 90 as soon as they became available in late 1994 which ended the performance issues on my multi-user system,