[Simh] "Raw" disk access

[Paul Koning]

> On Apr 12, 2017, at 5:03 PM, Alexander Schreiber <als at thangorodrim.ch> wrote:
> 
> On Wed, Apr 12, 2017 at 02:39:58PM -0400, Paul Koning wrote:
> 
>> As I recall, on VMS a disk is a file; a file spec consisting only of a device
>> name accesses that device.  So unlike some other operating systems where
>> special syscalls are needed for raw disk access, on VMS I would expect it to
>> be just a matter of accessing DUA1: or whatever.
> 
> Well, that is pretty much how it works under Linux, everything is a file
> (the old Unix principle).
> There isn't really a difference between accessing a file in the filesystem
> or accessing a raw block device. Windows appears to have similiar way where
> you can access raw block devices via the file API (but that is just from
> a quick search).

Yes, Linux is one of the friendly cases.  Other Unices may be trickier because you have to be aware of raw vs. file system block devices.  And then there is DOS, where you have to do BIOS calls to get raw disk I/O.

	paul