20 Feb
2019
20 Feb
'19
8:57 a.m.
On Wed, Feb 20, 2019 at 5:38 AM Paul Koning <paulkoning at 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