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systems:pdp7_unix [2015/12/29 23:54] – wktsystems:pdp7_unix [2015/12/29 23:55] – wkt
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 <code> <code>
 link(dir, file, newname) link(dir, file, newname)
- +</code>
-</file>+
  
 where //dir//  was a directory file in the current directory, //file//  an existing entry in that directory, and //newname//  the name of the link, which was added to the current directory. Because //dir//  needed to be in the current directory, it is evident that today's prohibition against links to directories was not enforced; the PDP-7 Unix file system had the shape of a general directed graph. where //dir//  was a directory file in the current directory, //file//  an existing entry in that directory, and //newname//  the name of the link, which was added to the current directory. Because //dir//  needed to be in the current directory, it is evident that today's prohibition against links to directories was not enforced; the PDP-7 Unix file system had the shape of a general directed graph.
Line 118: Line 117:
 <code> <code>
 sh comfile>output sh comfile>output
- +</code>
-</file>+
  
 The sequence of events was The sequence of events was
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 list list
 iocall attach user_output syn user_i/o iocall attach user_output syn user_i/o
- +</code>
-</file>+
  
 Even though this very clumsy sequence was used often during the Multics days, and would have been utterly straightforward to integrate into the Multics shell, the idea did not occur to us or anyone else at the time. I speculate that the reason it did not was the sheer size of the Multics project: the implementors of the IO system were at Bell Labs in Murray Hill, while the shell was done at MIT. We didn't consider making changes to the shell (it was //their//  program); correspondingly, the keepers of the shell may not even have known of the usefulness, albeit clumsiness, of //iocall//. (The 1969 Multics manual [4] lists //iocall//  as an `author-maintained,' that is non-standard, command.) Because both the Unix IO system and its shell were under the exclusive control of Thompson, when the right idea finally surfaced, it was a matter of an hour or so to implement it. Even though this very clumsy sequence was used often during the Multics days, and would have been utterly straightforward to integrate into the Multics shell, the idea did not occur to us or anyone else at the time. I speculate that the reason it did not was the sheer size of the Multics project: the implementors of the IO system were at Bell Labs in Murray Hill, while the shell was done at MIT. We didn't consider making changes to the shell (it was //their//  program); correspondingly, the keepers of the shell may not even have known of the usefulness, albeit clumsiness, of //iocall//. (The 1969 Multics manual [4] lists //iocall//  as an `author-maintained,' that is non-standard, command.) Because both the Unix IO system and its shell were under the exclusive control of Thompson, when the right idea finally surfaced, it was a matter of an hour or so to implement it.
systems/pdp7_unix.txt · Last modified: 2023/02/16 08:04 by admin