@jelabarre59
It is easy to forget that Microchannel was not just an x86 technology.
Both RISC System/6000 (early Power platforms) and AS/400 used Microchannel, and neither of these needed reference disks. I can't get away without mentioning the baby mainframe 9370 as well, but it used a PS/2 model 80 as it's I/O controller, so does not really count in this context.
In many ways, the way Microchannel worked a lot like PCI. Each card had a baked in ID string that was readable during the configuration stage of booting, to allow the OS to configure the support.
RS/6000 and AS/400 systems did have an advantage, though, because both OS's were controlled by IBM, so in much the same way that Apple has now, IBM controlled both the hardware and software layers of the systems. Before using a new card, you had to upgrade or patch the OS to include support for the new card, which provided the configuration method for the ID string for the card.
For PS/2 systems, the reference disk included an ADF (Adapter Description File) which was a text file with a description of the adapter, which actually sounds a lot like what the OS9 text description file that the previous poster referred to. I think that the BIOS in PS/2 systems would load the information for the installed cards from the reference diskette to set up the IRQs and memory, and store that in the NVRam, so that the BIOS would do the basic device configuration before the OS bootstrap.
Biting the hand that feeds IT
