Jeff Woods writes:

> Wirt wrote:
>  > That's not as bad as it sounds. DDS-2 tapes are readable by DDS-1
>  > drives as well, so long as the contents of the tapes are not
>  > compressed.
>
>  Uh...  No, they're not.

>         Recording mode:
>                DDS-1      DDS-2 DDS-3 DDS-4
>  Drive: ----------------- ----- ----- -----
>  DDS-0   <60m   60m
>  DDS-1   <60m   60m   90m
>  DDS-DC  <60m   60m   90m
>  DDS-2   <60m   60m   90m  120m
>  DDS-3   <60m   60m   90m  120m  125m
>  DDS-4                     120m  125m  150m
>         ----- ----- ----- ----- ----- -----
>  Capacity:    1.3GB   2GB   4GB  12GB  20GB  (Native; ignores
>  compression)
>
>  The recording mode used depends on the media inserted rather than on the
>  drive type.  This allows, for example, a DDS-3 drive to write on DDS-2
>  media in a manner readable by DDS-2 drives.

Jeff's correct. I wasn't paying sufficient attention to the word "media".
While what I wrote was correct, DDS1 drives can read tapes prepared on a DDS2
drive, so long as hardware compression is not on, and the tape is a DDS1
tape, it is the tape itself that determines the electrical format of how the
data will be written onto the tape.

Bruce Toback wrote me the following privately, but I'll repeat it here
nonetheless:

> But you're writing to DDS1 media, not DDS2. A DDS1 drive can read a DDS1
> tape written on a DDS2 drive. But it can't read a DDS2 tape. The write
> format changes when you switch media (there are identifying knockouts on
> the cartridge so that the drive can identify the media type).

Wirt Atmar

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