Subject: Re: Alpha2 & optical drive: still trying...
To: Allen Briggs <>
From: Monroe Williams <>
List: macbsd-general
Date: 03/04/1994 17:25:18
Allen writes:
> I'd rather it be SCSI-2 ;-)  I don't think the scsi drivers support the
> optical drives except as CD-ROMs, so we have to decide if it's a CD-ROM
> or a DISK device...  Or write a new driver.  One or the other.  I'll see

It's probably a lot closer to a disk than a CD-ROM, but that doesn't mean
the disk driver will work. :-/  

BTW, the jumper that makes it masquerade as a SCSI-1 device also gives
it the device type of DIRECT.  I think I was able to get the old kernel
to look at it by changing the jumper, but it still had bogus geometry.

> if I can borrow an MO drive from work to play with.  It would be nice to
> support them.  Doesn't system 7 try to eject the media when you boot BSD?

MacOS unmounts all mounted volumes during the shutdown.  Whether
unmounting the volume causes a physical eject or not is controlled by
the driver software for each device.  I think the APS driver has an
"eject on unmount" option that can be turned off to prevent this.  Or
you can just stick the cartridge back in right after it ejects.  Or you
can put the cart in the drive but NOT mount any MacOS partitions on it
before booting (i.e.  not load the driver).

In short: Yes, but there are several ways around it.

> They're on their way.  It's the scsi subdirectory of sys/arch/mac68k
> from ksrc.tgz.  I think I added code before to make it look like a
> disk device.

That sounds reasonable.  

(search, search, search...)

The code you sent me doesn't seem to have any special-case code for my
drive.  I'll assume that part is easy enough to fix.  

(browse, browse, browse...)

It looks to me like the geometry trouble may be in the function
sd_get_parms in "sd.c".  I'll have to look up the mode sense pages when
I get home tonight, but I don't remember seeing one in the docs that
contained the info this code is extracting (# of heads, sectors,

Incidentally, every SCSI formatting program I have used on this device
has given me either no geometry info at all (APS, HDT, etc.), or
incorrect info (old version of SilverLining).  I have all of the
correct numbers in printed manuals at home, if they need to be hard
coded.  (Something like 1 head, 10000 cylinders, I forget how many
sectors, 512-byte blocks.)

- monroe