[Simh] ATTaching real CDROM drive on simh

[Edward Berry]

Looking through the FAQ I noticed the statement that the network
interface was the only "real" device that could be used by simh.
Actually the CDROM also seems to work, at least for vax under linux.
This is not surprising because the recommended way of using a cdrom
is to put it in the drive, dd an image to a disk file, and attach that
to the virtual device. But under unix the device (/dev/cdrom or
whatever that links to) looks like a file which is identical to the
image you copied from it. Anyway:

sim> att rqb3 /dev/cdrom
File open error
(put hobbyist cdrom in drive which was empty before)
sim> att rqb3 /dev/cdrom
RQB: unit is read only
c
$ mount $1$DUB7/over=id
%MOUNT-I-WRITELOCK, volume is write locked
%MOUNT-I-MOUNTED, VAXVMS073    mounted on _$1$DUB7: (LCBVAX)
dismount DUB7:
$ mount/system $1$DUB7 VAXVMS073
$ dir disk$VAXVMS073:[000000.FORT066]
(and it works)

I wonder if this could be extended to read/write devices-
some time I will make a 2GB partition on a hard drive, att
it and try. Maybe it has to have some sort of file system
in order to be low-level formatted. As long as dd can read or
write it like a file, seems it should work. Not that would have
any real advantage over disk images, just for curiosity.

Ed