Looking for SMD drives (specific models)

On 4/12/2015 5:05 PM, Jules Richardson wrote: (actually Josh wrote this) The larger drives have more bits / track than the ones you have in the list. I suspect the 825mb and so forth may have too high a bit frequency for the ECC or CRC generation hardware in the controller. I don't recall the number of bits / track, but there were a couple of generations with about 20k / track, the 9766 was in that class. Then later there were drives which were twice that. The part we used to compute CRC for our drive at the time could not handle the frequency of the 40k tracks. And the parts for ECC were not mature to change to that technology, so we never supported the EMD (40k) drives. I have a CDC 160mb MMD which is probably compatible with the system you have. I believe the Ridge was out when we did our controllers. As to Jules's other mention, about the parameters, CDC recorded a well documented block of data on the first track with flaw map information. There are no drive parameters for SMD. We had a rom with a number of geometries, as well as some table with block capacities which were reported to the Reality OS for it to use the drive. Our interface was at a block count level, not a CHS layout level. The place to attack Ridge would be to look for the tables for the drives that Josh has in his list in the disk controller roms, and attempt to modify that table. That would assume one could modify that table, and there no protection on the rom such as a checksum that would mess up if you diddled the table. Thanks Jim