[rescue] zuluscsi wide sca80 or scsiknife sca as replacement to hd in sun ultra 60

[Dave McGuire]

On 5/27/26 13:56, Nathan Raymond via rescue wrote:
>      >> It's not an emulator when it's being used as an ordinary mass
>     storage
>      >> device.  When it's configured with a tape device, that *is* an
>      >> emulation, since it's faking the tape semantics, like move forward,
>      >> move backward, write tape mark, etc.
>      >
>      > Philosophical question, and I mean this as a discussion start rather
>      > than as anything even vaguely along the lines of "that's wrong!" (if
>      > for no other reason than that I would use the same terminology):
>      >
>      > Why is it emulation when something presents those semantics
>     backed by a
>      > file on an SD card, but not when backed by rust-coated plastic?
>      >
>      > Especially when it's not emulation to present a mass-storage device
>      > interface regardless of whether it's backed by a file on an SD
>     card or
>      > rust-coated metal platters?
> 
>         SCSI-attached tape uses the SCSI tape command set, which recognizes
>     the concept of a linear tape that moves back and forth, a sequential
>     access storage device...and it *moves the tape back and forth*.  A
>     ZuluSCSI implementing tape functionality fakes that sequential behavior
>     backed by a file on a random-access storage device.  That is emulation.
> 
> 
> Agreed. I also think emulation is an appropriate term when the 
> underlying thing (SD card, CompactFlash, etc.) has it's own standards 
> and protocols and can be removed from the SCSI emulator and used via its 
> own native interface independent of the emulator. I consider that 
> physical and functional modularity to be definitionally important. If 
> you could remove all the circuits and firmware related to SCSI on a 
> native SCSI block storage device, there's not much you do with the 
> underlying block storage bits and pieces.

   Your logic is sound and ordinarily I'd agree with your point.  But 
many early Suns were shipped with ESDI drives and Emulex MD21 SCSI->ESDI 
adapters, and MFM drives with Adaptec ACB4000 SCSI->MFM adapters. 
Nobody called them "emulators".

             -Dave

-- 
Dave McGuire, AK4HZ
New Kensington, PA