Stupid IBM DASD Tricks (ESDI)

I need a DASD for IBM 5363, which uses the IBM 0669 ESDI disk. This is the same type no. as the 115MB used in the IBM 8580 PS/2, but with a different feature code, and the block size switch set to 512 bytes, instead of 256 bytes. I've installed the 8580 variant in the 5363, with switches on the disk set per the IBM 5363 MIM specs, but the init routine pops an SRC indicating that the defect map is missing or damaged and refuses to LLF the disk. I suspect this is due to the fact that the factory defect map was written with 256 char. blocks instead of 512 char. blocks, but I'm not sure--and I don't trust the IBM error codes since they aren't exclusive. The only variable I haven't eliminated is the drive electronics. Before I spend time swapping drive boards, I wanted to consult with other folks who are prone to commit such foolishness and see if anyone had any wisdom to share. If the drive boards don't make any difference, my next project is an attempt to hack the ROM on the 8580's ESDI controller to see if I can make it work with 512 char. blocks, then try to re-write the defect map. -- David Wollmann ICQ: 10742063