On Sat, Jan 9, 2021, 2:55 PM David Gesswein <d...@pdp8online.com> wrote:
> On Sat, Jan 09, 2021 at 01:06:19PM -0700, Warner Losh wrote: > > > > DEC standard 144 of any help? > > > http://bitsavers.org/pdf/dec/standards/EL-00144_B_DEC_STD_144_Disk_Standard_for_Recording_and_Handling_Bad_Sectors_Nov76.pdf > > > > Warner > > > > Thanks for looking. > > That standard is only capable of marking bad sectors. It doesn't have the > information on where the bad sectors were remapped to. I took a quick look > at the DSM image. It looks like cylinder 511 is where the controller > tables are. This cylinder does have a different format. The data didn't > match this standard. > The rainbow has a different way to mark this stuff. Maybe there is some reuse in it? See "on disk format" in http://www.bitsavers.org/pdf/dec/rainbow/ms-dos/QV068-GZ_Rainbow_MS-DOS_V2.05_Technical_Documentation_Nov84.pdf which seemed oddly complex for such an early standard. It talks about N spare tracks that remapped sectors land in... I've never had a disk image that uses them though... worth a shot in the absence of other data... Warner >
