[sane-devel] 2 Questions about scsi

[Henning Meier-Geinitz]

Hi,

On Mon, Feb 24, 2003 at 11:33:41PM +0100, Franz Bakan wrote:
> 1. are all read commands 6 byte (08h) commands ?

All SCSI 08h commads (read) should be 6 bytes. However, there are
other read commands that are 10 bytes: 28h

"Should" as in "if the scanner conforms to the SCSI spec".

> 2. how long is a block read from a scanner with the 08h command
>    min, max or fixed?

I guess minimum is one byte, maximum is 2^24 bytes. At least that's
how the Mustek scanners work.

Byte explanation
0    0x08 (command code)
1    0x00 (whatever)
2    (size >> 16) & 0xff
3    (size >> 8) & 0xff
4    size & 0xff
5    magic (whatever)

As far as I know 0x08 isn't in the SCSI (2) spec for scanners at all
so you should expect all kinds of non-standard usage.

Bye,
  Henning