[TUHS] Unix v6 File System information

Noel Chiappa jnc at mercury.lcs.mit.edu
Mon Feb 22 03:50:08 AEST 2016

    > From: Random832 

    > They're 24 bits, aren't they?

Not according to the source:

	typedef	long		daddr_t;

	daddr_t	s_fsize;   	/* size in blocks of entire volume */
	short  	s_nfree;   	/* number of addresses in s_free */
	daddr_t	s_free[NICFREE];/* free block list */

(from param.h and filsys.h respectively).

    > From: Ron Natalie

    > The V6 block numbers were 24 bits.

Maybe you're thinking of the byte number within the file? The file length
was stored in an word plus a byte in the inode in V6:

	char	i_size0;
	char	*i_size1;  

but the block number in the device was a word:

	int	s_fsize;	/* size in blocks of entire volume */
	int	s_nfree;	/* number of in core free blocks (0-100) */
	int	s_free[100];	/* in core free blocks */

"Use the source, Luke!"


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