Editing IBM PS/2 (section)

===Micro Channel architecture===
{{main|Micro Channel architecture}}
With certain models to the IBM PS/2 line, [[Micro Channel architecture|Micro Channel Architecture]] (MCA) was also introduced.{{r|byte198706}} MCA was conceptually similar to the channel architecture of the [[IBM System/360]] mainframes. MCA was technically superior to [[Industry Standard Architecture|ISA]] and allowed for higher-speed communications within the system. The majority of MCA's features would be seen in later buses with the exception of: streaming-data procedure, channel-check reporting, error logging<ref>{{cite web|url=http://www.mcamafia.de/pdf/server_hmm_s30h2501_01.pdf|access-date=30 April 2023|title=Hardware Maintenance Manual|date=March 1996|website=mcamafia.de|archive-date=25 April 2023|archive-url=https://web.archive.org/web/20230425135058/http://www.mcamafia.de/pdf/server_hmm_s30h2501_01.pdf|url-status=live}}</ref> and internal bus-level video pass-through for devices like the [[IBM 8514]]. Transfer speeds were on par with the much later [[Peripheral Component Interconnect|PCI]] standard. MCA allowed one-to-one, card-to-card, and multi-card to processor simultaneous transaction management which is a feature of the [[PCI-X]] bus format.

Bus mastering capability, bus arbitration, and a primitive form of [[plug and play|plug-and-play]] management of hardware were all benefits of MCA. Gilbert Held in his 2000 book ''Server Management'' observes: "MCA used an early (and user-hostile) version of what we know now as 'Plug-N′-Play', requiring a special setup disk for each machine and each card."<ref name="Held2000">{{cite book|author=Gilbert Held|title=Server Management|url=https://books.google.com/books?id=Y9q-i_HGtAAC&pg=PA199|year=2000|publisher=CRC Press|isbn=978-1-4200-3106-5|page=199}}</ref> MCA never gained wide acceptance outside of the PS/2.

When setting up the card with its disk, all choices for interrupts and other changes were accomplished automatically by the PC reading the old configuration from the floppy disk. This made necessary changes, then recorded the new configuration to the floppy disk. This meant that the user must keep that same floppy disk matched to that particular PC. For a small organization with a few PCs, this was annoying, but less expensive and time-consuming than bringing in a PC technician to do installation. But for large organizations with hundreds or even thousands of PCs, permanently matching each PC with its own floppy disk was a logistical nightmare. Without the original, (and correctly updated) floppy disk, no changes could be made to the PC's cards.