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Format:Xexor ARC file format

1,114 bytes added, 19:20, 17 December 2010
[[Category:Cpctech.org]]
<div style="border: 1px solid rgb(228, 222, 222); margin: 0px 0px 5px; padding: 0.5em 1em; background-color: rgb(249, 249, 249);"><center>'''''This article originally came from Kevin Thackers' archive at [http://www.cpctech.org.uk http://www.cpctech.org.uk].'''''</center></div>
|-
| 1
| 0Drive Definition Byte
|-
| 1
|}
The drive definition byte is as follows: {| border="1"|-! Bit ! Description|-| 3 | Double-stepped if set|-| 2| Head when not double-sided|-| 1 | Unused|-| 0| Double-sided when set|} If the image is double-sided, alternate heads are stored for each cylinder. ARC files written by older versions of Xexor have the following header(ie. XA and DDB missing):
{| border="1"
! Description
|-
| 1 2| Sector Size and Flags?
|-
| 1 | Flags?|-| &nbsp;?
| Compressed sector data
|}
9 means same byte for entire The Sector Size and Flags are stored as a word (LSB first), containing the stored data length (when not empty), compression flag, and deleted data address mark. The top 3 bits of the Size are flags, with the bottom 13 bits containing the size of the stored data (when not empty). A sector? 80 which does not have a deleted data address mark and contains only E5 bytes is considered empty. In this case, the byte? then there top 3 bits will be 100 and the size is no ignored. WinAPE stores this as #8009, but it could be any value from #0000 to #1FFF or #8000 to #9FFF. For all other sectors: {| border="1"|-! Bit! Description|-| 15| RLE compressed sector if set (see below)|-| 14| Sector has Deleted Data Address Mark if set (DDAM)|-| 13| Sector data is present if set (not empty)|} Sector data is also assumed to be present if bit 14 is set, regardless of bit 13.
== Compression scheme ==
MacDeath
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