From: William Levak (wlevak_at_cyberspace.org)
Date: 2004-08-27 23:28:38
On Thu, 26 Aug 2004, Baltissen, GJPAA (Ruud) wrote:
> Hallo Pasi,
>
>
> > 1581 uses "super side blocks" to extend the max size of a REL file.
> > See the 1581 user manual for detailed information (should be available
> > in electronic form somewhere).
>
> I have a manual that covers all drives but that doesn't mention these SSBs.
> I downloaded the manual from Project 64 but that doesn' mention it either.
> So any other info is welcome!
>From page 122 of the 1581 User's guide:
=============================================================================
RELATIVE FILE FORMAT
BYTE DEFINITION
------------------------------------------------------------------------
DATA BLOCK
0,1 Track and sector of next data block.
2-255 254 bytes of data. Empty records contain $FF
(all binary ones) in the first byte followed by $00
(binary all zeros) to the end of the record. Partially
filled records are padded with nulls ($00).
-------------------------------------------------------------------------
SIDE SECTOR BLOCK
0-1 Track and sector of next side sector block in this group
2 Side sector number (0-5)
3 Record length
4-5 Track and sector of first side sector (number 0)
6-7 Track and sector of second side sector (number 1)
8-9 Track and sector of third side sector (number 2)
10-11 Track and sector of fourth side sector (number 3)
12-13 Track and sector of fifth side sector (number 4)
14-15 Track and sector of sixth side sector (number 5)
16-255 Track and sector pointers to 120 data blocks.
-----------------------------------------------------------------------------
SUPER SIDE SECTOR BLOCK
0-1 Track and sector of first side sector in group 0
2 $FF
3-4 Track and sector of first side sector in group 0
5-6 Track and sector of first side sector in group 1
253-254 Track and sector of first side sector in group 125
------------------------------------------------------------------------------
The super side sector has pointers to 126 groups of side sectors.
Each of these groups contains 6 side sectors each. 126 x 6 x 120 x 254 =
23,042,880 bytes(maximum relative file size)
===============================================================================
End of transcrition.
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