liffile(5)                LIF Utilities                liffile(5)


NAME
       liffile - HP9114 LIF disk image file

DESCRIPTION
       The  HP9114  LIF  disk image file format was designed as a
       simple way to store HP9114 disk images on  a  larger  com-
       puter,  and  to  allow  programs  to be written to process
       those images (including writing them back  to  a  physical
       disk).

IMAGE FILE & LIF LOGICAL BLOCKS
       The  file consists of a raw dump of the data blocks on the
       disk, in increasing numerical order. There are no  headers
       or trailers added, either for the entire image or for each
       block. That is to say :

       Bytes 0 to 255 are LIF logical block 0

       Bytes 256 to 511 are LIF logical block 1

       Bytes 512 to 767 are LIF logical block 2

       and so on

       As an HP9114 disk contains 2464 user blocks (organised  as
       77 cylinders, 2 heads, and 16 sectors per track, with each
       sector being 1 block), an image file is  always  2464*256,
       or 630784, bytes long.

LIF DISK PHYSICAL BLOCKS
       The  correspondence  between  the  logical  block  numbers
       described in the last  section  and  the  physical  sector
       addresses  on the disk is also straightforward. The cylin-
       ders on the disk are numbered from 0 to 76.  the  2  heads
       (sides)  are called 0 and 1, and the sectors on each track
       are numbered from 0 to 16. Then :

       Block 0 is cylinder 0, head 0, sector 1

       Block 1 is cylinder 0, head 0, sector 2

       Continuing on cylinder 0, head 0, until...

       Block 15 is cylinder 0, head 0, sector 16

       Block 16 is cylinder 0, head 1, sector 1

       Continuing on cylinder 0, head 1 until...

       Block 31 is cylinder 0, head 1, sector 16

       Block 32 is cylinder 1, head 0, sector 1





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liffile(5)                LIF Utilities                liffile(5)


       And continuing in this manner for all 77 cylinders

PSEUDO-CODE TO WRITE AN IMAGE TO DISK
       Assuming the necessary functions exist to  seek  the  disk
       head  to  a  particular cylinder ( seek() ) and to write a
       256 byte sector ( writesector(cylinder,head,sector,data[])
       )  then it is reasonably easy to write a program to trans-
       fer a  disk  image  to  a  physical  disk.  The  following
       pseudo-code gives the basic idea :

       declare blockbuffer to be 256 bytes long

       open(image file)

       for cylinder=0 to 76

       seek(cylinder)

       for head = 0 to 1

       for sector = 1 to 16

       read next 256 bytes of image file into blockbuffer

       writesector(cylinder,head,sector,blockbuffer)

       next sector

       next head

       next cylinder

       close(image file)

       end

REFERENCES
       The  logical  block  structure of a LIF device is given in
       appendix D of the HP-IL Module for the HP71  Owner's  man-
       ual.   The  relationship  between  LIF  logical blocks and
       physical disk sectors was determined experimentally.

RESTRICTIONS
       Although the LIF Utilities for linux  are  released  under
       the GNU public license, the only restriction placed on the
       use of this image file format is that no (other)  restric-
       tions  may  be  placed  on  its use. Anybody is welcome to
       write programs using this file format (for example to con-
       vert  the  image  files into other formats, or to transfer
       between physical disks and the image format) for any  com-
       puter  or  operating  system, and to distribute these pro-
       grams under any license terms they choose.





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liffile(5)                LIF Utilities                liffile(5)


AUTHOR
       The LIF image file format  was  designed  by  Tony  Duell,
       ard@p850ug1.demon.co.uk


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