SCSI Tape Emulator

[jim stephens]

On 10/10/2016 8:24 AM, Charles Anthony wrote:
> On Mon, Oct 10, 2016 at 4:51 AM, Dave Wade <dave.g4ugm at gmail.com> wrote:
>
>>> Would it not be a SMOP to get a SCSI2SD device to emulate a tape drive?
>> I am not sure, it looks there is some code in there for tape but its very
>> minimal.
>> In addition there are no interfaces on the card to select the ".tap" file
>> to be used.
>>
>>
> Not needed; copy the .tap file directly to the SD card, no partition
> tables, no file system:
>
>    dd if=foo.tap of=/dev/sdx
>
> Fix up the firmwre (a SMOP) with a pointer to where you are in the .tap
> data; it starts at block 0, offset 0 at the location would be the first
> block size word of the .tap data. Treat the disk as a file; read reads the
> data at the pointer and moves the pointer to the end of the read. Assuming
> LBA, the pointer value maps directly to block number/offset.
>
> Fill out the SCSI tape commands to use the pointer and the data.
>
> -- Charles
>
>
The only thing I might mention was that the brand name was used on some 
initiators to either behave differently or not at all.  We had an 
emulation in our SCSI development package that emulated an ST-150 and it 
worked on  most initiators, but there were some who didn't like it, and 
once we found out what the identification had to be things were good.

I don't recall what behavior was expected in the off cases, other than 
possibly the block sizes of the transfers.

One could also emulate a half inch drive, vs. a QIC, which can have 
variable block sizes.  Emulating QIC is a bit simpler as you don't have 
to deal with retrieving excess data commands which you might with half inch.

Our system was Peer Protocols 5000 and 7000.  We also had a 0550 narrow 
capture card.  Would be interested if anyone worked with it.
thanks
Jim