I was there. I installed hundreds of the things. I still own 2 of them. The term "PC compatible" is about software, not hardware. It's not about slots. For ins

I was there. I installed hundreds of the things. I still own 2 of them. The term "PC compatible" is about software, not hardware. It's not about slots. For instance, laptops were and are still PC compatibles and 99% of laptops have no expansion slots. The PS/2 range ran bog-standard unmodified PC DOS and MS-DOS, and unmodified DR Concurrent DOS. It ran plain unmodified standard Windows 2, 3 and 3.1. I put it on them. I deployed them in production. I have personally done this; this is not research or hearsay. I did it myself. In my basement right now is a PS/2 Model 80 with 16MB of RAM that runs Windows NT Server 3.51. PS/2s were PCs. Furthermore MCA was not "out of reach to clone makers". I personally installed at least one Apricot VXFT server with SCO UNIX, and MCA slots. http://insight.actapricot.org/insight/products/servers/vxft/vxftmain.htm http://insight.actapricot.org/insight/products/servers/vxft/... There were other models too: https://ardent-tool.com/Apricot/ https://ardent-tool.com/Apricot/ Tandy, ACT Apricot, Fujitsu, Siemens-Nixdorf, Olivetti, AST, and others all sold MCA machines. It cost money for a licence, sure, but it was not IBM-only. The list of members was not insignificant: https://en.wikipedia.org/wiki/Micro_Channel_Developers_Association https://en.wikipedia.org/wiki/Micro_Channel_Developers_Assoc... MCA lost out to VL-Bus, EISA, and ultimately to PCI, but it did OK for a while. There wasn't really anything wrong with MCA. Its issues were two fold and relatively minor: [1] EISA, VLB and PCI could co-exist with ISA. MCA couldn't. [2] Manufacturers had to pay to licence it. If IBM's OS/2 plan had worked, and OS/2 had been a 386 OS and thus been compelling to DOS users, then in 1987, the PC industry would have had a pre-emptive multitasking OS, and by 1988, it would have had a GUI too. Windows 3 would never have happened. There's a chance that 386BSD might not have happened. Linux almost definitely wouldn't -- it was 3 years later. Then IBM's package of a fancy new PCs with shiny new ports and graphics and memory, with a fancy multitasking OS, plus a fancy new 32-bit bus, would have been compelling. But it dropped the ball. It insisted on the 286 being included.