A/UX SCSI Manager Extension
by kelly king and andrew kass

What is it?

A/UX does not support the Macintosh SCSI Manager for Mac applications or 
drivers, for many reasons, primarily security.  It would be unwise to allow 
arbitrary user-level processes, of which the Mac environment is one under A/UX,
to read and write to SCSI devices at the block level, or format the active root
filesystem's hard drive.

This extension implements the Macintosh SCSI Manager under A/UX 3.0.x.  This 
allows you to run most Macintosh applications and drivers that talk to the 
Macintosh SCSI manager under A/UX.

This software was originally written to support audio CD access under A/UX, 
and this is still its most useful feature.  With this extension installed, 
you can use the standard Apple CD-ROM driver, version 4.0.x, and any audio 
software, such as CD Remote, the CD Remote Init and the Audio access and 
foreign file access extensions.

InstallationÉ

Simply drop it onto any A/UX System Folders, shared or private, that you wish 
to use it with.  Be sure not to rename the extension, or make sure that it 
retains a name that causes it to load before any extensions that might use 
the SCSI manager.

Then be sure to change the permissions or ownership of the Ò/dev/scsi/#Ó 
nodes that correspond to the scsi devices you wish to allow access to.  For 
example, if you have a SCSI CD-ROM drive at SCSI id 3, and you want everyone 
to have access to this device from Mac applications and drivers, you would 
type this command at the UNIX prompt:
$ chmod oug+rw /dev/scsi/3
This allows everyone access to the device at scsi id 3.  Note that this 
assumes that you have not configured the devscsi module out of the kernel, 
since A/UX 3.0 ships with it already installed.

Now simply logout of the Mac environment, and log back in.  The SCSI Manager 
will show it's icon during startup.  If it is unable to install for some 
reason (usually permissions or low memory conditions) it will display 
its icon with an ÒXÓ through it.  This extension takes up about 36k in the 
system heap.

How does it work?

The Macintosh SCSI manager is not currently asynchronous, and in fact 
ÒbabysitsÓ the scsi communication through all of its phases.  One cannot own 
a system resource, like the SCSI bus, from a user-level process under UNIX, 
without causing headaches for the main UNIX kernel.  In particular, the code 
that is issuing a SCSI transaction could cause a page fault in between phases, 
which would be problematic, to say the least.

This software is essentially a SCSI manager state emulator.  It builds a 
single atomic SCSI request, based on the SCSI calls that the caller makes, 
and issues that call during the completion or data phase, depending on 
whether data is being transferred.

CaveatsÉ

This software is provided Òas isÓ for non-commercial use.  It should not be 
redistributed without this file, and it must not be sold or included in a 
commercial product without written consent from the authors.  The authors do 
not take any responsibility, whatsoever, for any data loss or compromise of 
system integrity that should result in the use, or misuse, of this software.  
The authors do not offer any support for this product.

Version history:

1.0b4 ak
Upgraded to handle complex TIBs and preallocate buffer memory used in data
transfers. Now supports Double Speed, Photo CD, Audio CD, data CD and foreign
file access.

1.0b3 ak
Internal release only. Known bugs.

1.0b2 ak
Upgraded to support audio CDs with 4.0.x CD-ROM drivers. Unfortunately, I broke
the data CD support in the process.

1.0b1 kk
Initial release, only supported very simple TIBs and 3.2 CD drivers.


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