[pups] Major/minor device numbers and device names for MSCP drives?

[C. H. Dickman]

Robert Armstrong wrote:
>   Probably this is documented somewhere, but I really need a pointer 
> or a brief tutorial on the major/minor device numbers for mknod() and 
> the device names for MSCP drives in 2.11bsd.
>  
>   If I have a really simple PDP with an RQDXn and one RDxx disk, then 
> the device name is conventionally /dev/ra0x and the first partition, 
> ra0a is (5,0), the second, ra0b, is (5,1), etc.  Pretty easy.
>  
>   If I have two drives on my single RQDXn, then the second hard disk 
> is /dev/ra1 and ra1a is (5,8), ra1b is (5,9), etc.  I guess the offset 
> of 8 must be the maximum number of partitions on a drive - OK, I'm 
> still with you.
>  
>   But what if I have a second MSCP controller?  Assuming that I've 
> built the kernel to handle it and modified dtab to autoconfigure it, 
> that is.  What are the usual names and mknod() numbers for the drives 
> on the second controller?
The second controller starts at ra8a (5, 8), and ra8a must be MSCP unit 0.
>   Worse, what if the MSCP controller isn't a RQDX but is a real 
> UDA/QDA ?  Now the drives have their own MSCP unit numbers that can be 
> anything from 0 to 250 - where does this figure in?
An MSCP unit number greater than 8 cannot be accessed from 2.11BSD.
>   Same question for TMSCP - what if I have more than one tape 
> controller?  This case is easier, though, since TMSCP controllers 
> normally have only one drive associated with them.
Don't know a think about it...
> Thanks,
> Bob Armstrong
>
-chuck