[Coco] Identification Sector (LSN 0)

Robert Gault robert.gault at att.net
Sun Oct 20 21:34:35 EDT 2013


Luis Fernández wrote:
> I need a little help
> Sector Identification in (LSN 0) in NitrOS-9.VHD
> DD.OPT $ 3F Path descriptor options
> I need to know that there are from $ 3F to $ FF
> is supposed to be the The RBF Manager Definitions of the Path Descriptor
>
>
>
>
> I fail per $5A align with who I think are the 90 cylinders
> since they are $ 5A * $ 40 Tracks * $ 40 Sectors = $5A000
> Size of partition ? = $5A000 * 256 Bytes Per Sectors = $5A00000
>
>   		 	   		

"The RBF manager Option Section Definitions (PD.OPT Section)
(copied fromm the device descriptor)
PD.DTP  $20   1     1=RBF
PD.DRV  $21   1     Drive # 0..n
PD.STP  $22   1     Step rate
PD.TYP  $23   1     Device type
PD.DNS  $24   1     Density
PD.CYL  $25   2     # of cylinders (tracks)
PD.SID  $27   1     number of sides
PD.VFY  $28   1     0=verify writes
PD.SCT  $29   2     sectors per track
PD.T0S  $2B   2     sectors per track0
PD.ILV  $2D   1     sector interleave
PD.SAS  $2E   1     segment allocation size
PD.TFM  $2F   1     DMA transfer mode
PD.EXTEN$30   2     path extension
PD.STOFF$32   1     sector/track offsets
PD.ATT  $33   1     file attributes
PD.FD   $34   3     file descriptor PSN
PD.DFD  $37   3     directory file descriptor PSN
PD.DCP  $3A   4     file directory pointer
PD.DVT  $3E   2     address of device table

The above are in the RBF Path descriptor but were taken from the drives LSN0 
starting at $3F. That means in LSN0 the above runs from $3F to $5E.

Your math is correct. DD.TOT=$5A000 sector and in the DD.OPT section there are 
$5A cylinders(tracks), $40 "sides", and $40 sectors per track. 
$5A*$40*$40=$5A000 and at $100 bytes per sector $5A00000 bytes in the OS-9 
section of the .vhd image.




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