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3-8 A-61124 March 1999
Retrieving images and
headers
Headers and images are transferred to the host system via the
SCSI Read command. The data can be transferred in one of
three forms: header only, image only, or compound image, i.e.,
header with image. To determine the form, set the transfer type
within the SCSI Read command.
The image can be read in one of two ways:
• Read the header, then read the image.
• Read the compound image.
IMPORTANT:
The header should always be read before the
image. The header contains information
pertinent to the successful transfer of the image,
e.g., image size, and should be read prior to
reading the image.
The following table illustrates the results of one Read command
followed by another. Assume that Image 1 is followed by Image
2.
Last Transfer
Requested
Transfer
Resultant
Transfer
Compound (Header 1 and Image
1)
Compound Header 2
Image 2
Compound (Header 1 and Image
1)
Header Header 2
Compound (Header 1 and Image
1)
Image Image 2*
Header 1 Compound Header 2**
Image 2
Header 1 Header Header 2**
Header 1 Image Image 1
Image 1 Compound Header 2
Image 2
Image 1 Header Header 2
Image 1 Image Image 2*
* Note that Header 2 was not transferred. This is not recommended.
** Note that Image 1 was not transferred.