OS9 login / shutdown

Tony Duell ard at p850ug1.demon.co.uk
Wed Nov 23 13:32:05 CST 2005

Warning : My knowledge of OS-9 is beased entirely on the 6809 (8 bit) 
version, I've never used a 68K version. I suspect some of the things that 
I think were 'misisng' on the 6809 version (like shell variables and 
wildcards) are present in the stnadard shell of the 68K version. But 

> To begin to understand it, consider it to be a CP/M clone with
> multi-user extensions. List the files in the system directory and most

Internally it's not a bit like CP/M

> of them will be vaguely familiar utilities. I believe "DIR" was the
> command. If not, use commands from other common OS's as it was the same
> as one of them (LIST maybe?).

A few things....

At least in the 6809 version there was no equivalent to the PATH for 
lookin for commands. At any time, a user had 2 default directories. One 
was the data directory, the other the execution directory. The latter is 
what was searched for commands.

File paths were somewhat unix-like. But you don't mount all the disks 
into one filesystem. Rather, the first part of each complete file path is 
the device name. I remeember floppies called /D0, /D1. etc and hard 
drives /H0, /H1, etc. Some machines have a device /DD which is a copy of 
the device descriptor for the drive you want to be the default.

So, for example, a file on the second floppy drive might be specified 
soemthing like : /D1/pascal/demo.pas

Two of the built-in commands of the stnadard shell were CHD (to set the 
data directory) and CHX (to set the execution directory). Typically the 
latter is set to /D)/CMDS (that being the normal equivalent of /bin on a 
unix box). Note that if you chanve floppies, you have to type CHX /D0/CMDS
(even if the directory was /D)/CMDS  both before and after the change), 
since IIRC, it stores a pointer to some part of that directory in RAM, 
not the name iteslf.

IIRC, the stnadard name for the directory command was DIR, but of course 
as it was simply a program loaded and run from the execution directory, 
it could be called anything.


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