[net.micro.pc] File formats

markz@microsoft.UUCP (Mark Zbikowski) (01/09/84)

	"... Why MS did not use the standard Intel
	format for libraries I have no idea!..."

The Intel object format is based on variable sized records.  To implement
the Intel library format would require reading and processing the LIB file
in order to search it.  On a floppy based system this can be unreasonably
slow.  Having a hash table at the end of the LIB file speeds things up
dramatically.

The 512-byte alignment is another speed improvement for floppies; LINK's
overflow-to-disk processing mechanism is used to page in the required sections
of the library.

	"...header and a checksum. Absolutely no-one checks either of these
	fields, a fact made clear by the fact that the MS (IBM) PASCAL EXE
	files are distributed with the first two bytes reversed!..."

The checksum field is provided in case people do want to do checksum
verification.  The signature field is checked; the EXEC system call uses
these two bytes to determine if the file is either an EXE file or a COM file.
Using a name to guide in interpretation of the contents is pretty bogus.