On Wed, Feb 20, 2019 at 5:38 AM Paul Koning <paulkon...@comcast.net> wrote:
> > > You're misinterpreting "spare". MSCP exposes the user address space as > contiguous LBAs, for which it uses 51 sectors per track. The spare sector > is used to do bad sector replacement. That is invisible to users, it > doesn't affect the LBA addressing. dd, like any other host-resident code, > sees the user address space. It will copy MSCP devices correctly. > > Yes; I agree that the MSCP conceals the spare sector when RSTS accesses the disk through MSCP in the case of the *hardware*. However, in the original posters case, the SIMH disk image is being copied to the RA81 drive without the benefit of the MSCP controller (if I understand correctly). This would lead to track misalignment and could result in the observed behavior. The SIMH MSCP emulation is not doing the spare sector correctly; it is not including the spare sectors on the RA81 disk image. -- Charles