I know the topic is old, but the people that responded back in the day never understood how boot blocks on hard disks came to be back in the early OS 1.2/1.3 days. They were giving advice on things they didn't understand.
FWIW, GVP had the first RDBs (with a floppy boot disk, loading the SCSIDEV driver with Binddrivers) before OS 1.3 came out and fixed the expansion.library boot ROM bug in OS 1.2. The GVP 1.0 ROMs just had to be fitted to the cards when OS 1.3 came out - no reformat. C= was still on the A2090 at this point, and the 2090a came out shortly after OS 1.3 did - but neither card was pretty to partition. C= then effectively borrowed and modified what GVP basically had done with the RDB when they produced the A2091, and standardized disk boot blocks for all developers making disk controllers. This is why GVP, C=, Supra, Microbotics, and most other SCSI controllers can have disks prepped on them moved between controller makers, and generally work.
This issue for the user was likely caused by the original 1.0/2.x ROM set on an original GVP Impact SCSI HC or SCSI+RAM controller, and a corrupted RDB on the disk. I used to fix this back in the day on the phone at GVP Tech Support. There is a way to do it with the original floppy disk, and it's CLI-based prep tools, but using the newer v3 FastPrep floppy's tools and driver is easier.
The solution is to obtain the newer GVP boot floppy with the v3.x gvpscsi driver in the Expansion folder. Disable the ROMs on the SCSI card, boot from the FastPrep floppy, binddrivers will get called by default, load the v3.x gvpscsi.device driver from Expansion. Use FastPrep/ExpertPrep to Erase the RDB, and program in a new set of partitions, format them, then copy a Workbench 1.3 and Extras disk to the first partition. Re-enable the ROM with the jumper, and reboot.
It would have been a good time to also obtain the newer v3.15 ROM (not a 4.x), as it will run faster than with the pre v3.x scsidev.device driver. The RDB that FastPrep writes should still boot under the old GVP ROM set in the meantime.
