65
votes
Why did Unix use slash as the directory separator?
Primordial Unix on the PDP-7 was in many ways very different from what we know today. Directories existed but were very awkward to use; in practice most work was done in a single directory. Most ...
- 9,200
35
votes
Accepted
What are the major technical difference between Multics and Unix?
From this list of Multics features, almost all are recognizable in modern UNIX-style systems in one form or another. Looking for distinctions between is two is made difficult due to the longevity of ...
- 3,483
29
votes
Accepted
How did Multics make library calls available as shell commands?
Yes. All external entry points in compiled "segments" (← Multics for "files") were exposed as names in the file system. Very strange by today's standards but that's what they did....
- 5,468
25
votes
Accepted
Are there runnable Multics systems available?
There are a number of ways to use Multics today.
One option is to run it locally under an emulator. The source code that's available should run (under emulation) on most Linux systems, Mac OS X, and ...
- 9,200
19
votes
How did Multics make library calls available as shell commands?
Commands in Multics were functions, not standalone programs. So, the command:
delete myfile
was the same as:
call delete( "myfile" );
in PL/I.
In practice, this was rather troublesome. ...
- 1,311
16
votes
What are the major technical difference between Multics and Unix?
In Multics, not only was all data mapped into memory, but all binary executables were what we now call DLLs. There was no natural "main program" concept: every binary executable was a ...
- 1,311
16
votes
Are there runnable Multics systems available?
Yes. The dps8m emulator simulates the GE-645 machines well enough to run Multics. The open-sourced code has been successfully run under the emulator. There's even a getting started guide with some ...
- 12.8k
10
votes
What are the major technical difference between Multics and Unix?
A couple other significant differences between Multics and early Unix systems in the security area:
Multics had rings (8 in commercial versions), whereas Unix only had two effective rings -- ...
- 201
9
votes
What are the major technical difference between Multics and Unix?
Another significant difference between Multics and Unix was the size of the virtual memory accessible to a process.
It is true that each Multics segment was limited to 255K 36-bit words in length. ...
- 91
8
votes
What are the major technical difference between Multics and Unix?
All these answers accurately describe the most salient features of Multics. One of the main consequences was that it could only run on specialized hardware.
From a programmer's standpoint, dynamic ...
- 81
7
votes
How did Multics make library calls available as shell commands?
If you want an analogy with a modern system, when you executed a command
command_name arg1 arg2 arg3 ...
The shell (called "command processor" on Multics) would perform the rough equivalent ...
- 1,635
6
votes
What are the major technical difference between Multics and Unix?
Perhaps the best way of thinking about it is that Unix basically is a minimal implementation of Multics (the ideas in it a least) with absolutely everything that was not strictly necessary to bring up ...
- 161
3
votes
How did Multics make library calls available as shell commands?
Presuming you mean this article, it seems clear from his habit of writing CTSS commands in a a high-level language ("MAD", the Michigan Algorithm Decoder) that he means something similar to ...
- 9,723
3
votes
Why did Unix use slash as the directory separator?
There were other hierarchical file systems around.
The Burroughs operating systems used (and as Unisys, still do) /
Although in a someone clunky way:
(PHYS212)ACOUSTICS/RAYS/OUTPUT ON USERPACK
^^^^ ...
- 356
2
votes
When was the term Multics (operating system) coined and by whom?
Not an answer, really, but I would suppose that the name would have been seen as natural for Project MAC's goals.
The name MAC, in one of its many interpretations, stood for "Multiple Access ...
- 31.3k
2
votes
Why did Unix use slash as the directory separator?
DTSS, developed around the same time as Multics, and influenced by it, used : as the directory separator. A leading : was used for absolute paths (starting at the root directory). There was no easy ...
- 311
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