The SLIM Service for CTOS:
Access to DOS (FAT) Partitions from CTOS Applications

The SLIM Service for CTOS provides your computer with access to files and directories stored on a DOS partition or floppy disk.  Rather than using the MSDos Read commands, ordinary (ie: existing and new) CTOS commands and applications can be used instead.  The SLIM Service thereby makes a larger data space on your disk available to CTOS and its applications.  This complemetary version of the SLIM service provides READ-ONLY access to the DOS file space -- it cannot modify any data on the disk.


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What can you do with the SLIM service?

The SLIM service provides file and directory access to existing DOS files located on a DOS partition or DOS floppy diskette.  It also emulates key CTOS structures necessary to navigate your DOS partition, including wild-card support.  (In this discussion, the term "DOS partition" will include support DOS floppy diskettes unless otherwise noted).

Examples of what you can do with SLIM include:

- Copy files to and from the DOS partition.

- Open files on the DOS partition in the CTOS Editor.

- Attach DOS partition files to mail messages.

- Expand DOS partition file names using wildcard characters in Executive command forms.

- List the contents of a directory using the Executive's List command.

- Determine the amount of remaining free space on a DOS partition using the Executive's Volume Status command.

Some CTOS applications "parse" file specifications into a known (CTOS) format and expect all file names to conform to that format.  Such applications may not be able to see the entire file space of the DOS partition.

The SLIM service automatically detects the following types of DOS partitions on your workstation:

	- A DOS primary partition
	- A DOS logical drive in an extended partition

Floppy diskettes are mounted when you first try to access them, not when they are first inserted.


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Will the SLIM service affect file system performance?

The SLIM service makes use of multiple processes to ensure minimal impact upon access to CTOS files.  The main SLIM process checks file specifications and forwards unrecognized file operations to the CTOS file system immediately.  All other activities are handled by a second SLIM service process that does not interfere with file routing and distribution.  Unlike other file system filters, this design minimizes the impact on CTOS file system access.  The presense of SLIM on the system is nearly undetectable.


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How do you specify files on the DOS partition?

CTOS file specifications allow for a volume, one directory, and a file name.  You specify CTOS files as follows:

	[VOLUME]FILENAME

DOS file specifications allow for a drive letter, any number of directories separated by backslashes (\), and a file name, each conforming to a short 8 character plus 3 character extension naming convention (called the 8.3 naming convention).  When using M/S-DOS and Windoows, you specify files as follows:

	X:\                    - the root directory of the drive X
	X:\FILE                - a file in the root directory
	X:\DIR\FILE            - a file in a subdirectory of the root directory
	X:\DIR\...\DIR\FILE    - a file buried deep in the the directory tree

Naturally, these two file specification formats are rather different.  The SLIM service provides a means by which to intermingle the two formats in a more convenient manner.  The format used by SLIM looks like a CTOS file specification so that most applications that parse it will understand the components.

SLIM service file specifications consist of a drive letter and colon or a DOS volume label, directory and subdirectory names as needed, and the file name.  Directory names may be separated by the usual angle brackets for CTOS, and/or by a slash character.  Either the forward slash or the backward slash may be used consistently in the same file specification, but not both.  When using the SLIM service, you specify files as follows (an astrisk (*) indicates the prefered format):

The file X:\DIR\FILE, a file in a subdirectory of the root directory:

*	[X:]FILE
	[X:]/DIR/FILE
	[X:]\DIR\FILE

The file X:\FILE, a file in the root directory:

*	[X:]<.>FILE
	[X:]/FILE
	[X:]\FILE

The file X:\DIR1\DIR2\DIR3\FILE, a file buried deep in the the directory tree:

*	[X:]\DIR2\DIR3\FILE
*	[X:]/DIR2/DIR3/FILE
*	[X:]FILE
*	[X:]FILE
	[X:]\DIR1\DIR2\DIR3\FILE
	[X:]/DIR1/DIR2/DIR3/FILE
	[X:]FILE

In addition to using the drive letter, the volume label may be used to select a drive.  If your CTOS partition has the same volume name as your DOS partition label, add a plus (+) character to the end of the volume label.  If the label for drive X is "LABELX", then the following are also valid specifications:

*	[LABELX]FILE
*	[LABELX]<.>FILE
*	[LABELX]\DIR2\DIR3\FILE

Some CTOS applications may not accept a particular directory specification format.  In that case, try a different format.  For instance, the CTOS Editor accepts specs like [X:]FILE but not like [X:]\DIR2\DIR3\FILE.

See the next section for how drive letters are assigned.

Additionally, the SLIM service works with B-Net node names.  Simply apply the node specification in the same manner as with CTOS file specifications:

	{NODE}[X:]\DIR2\DIR3\FILE

The SLIM service also works with Cluster Access B-Net as described above.


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How do you install the SLIM service?

The SLIM service can be installed by copying the executable file to a directory and running it from the Executive command line or from the startup file SysInit.jcl.  For organization purposes, suppose that the directory [Sys] is created to hold the SLIM service files.  Copy the file ReadOnly>SlimService.Run to the directory [Sys].  Then, to have the SLIM service installed during system initiallization, add the following line to your system initialization file ([Sys]SysInit.jcl):

	$RUN [Sys]ReadOnly>SlimService.Run

There are no command line parameters that affect the SLIM service.

When the SLIM service is installed in memory, it displays the list of disk partitions and the drive letter associated with each.  Note that the SLIM service assigns drive letters in a manner consistent with Windows NT.  M/S-DOS uses a slightly different method to assign drive letters, and which letter you use may differ between CTOS and M/S-DOS.

Like M/S-DOS, the first hard disk with a DOS primary partition is assigned drive letter C.  The first two floppy diskette drives on the system are assigned drive letters A and B.  Subsequent DOS partitions/logical drives are assigned the next available drive letter (eg: D, E, etc.).  This version of the SLIM service supports drives A thru F.


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What should you avoid?

The following are examples of activities which are not supported with the SLIM service:

- The SLIM service requires CTOS III.  It cannot be used with older versions of the operating system.

- The SLIM service manages the file space in the DOS partition.  Because of this, any other application that manages the DOS partition MUST NOT be used while the SLIM service is running.  Such programs include:

	MSDOS Write
	PC Emulator
	Vpc

- Do not use Volume Archive/Restore Archive to archive a DOS partition.  Use an appropriate M/S-DOS or Windows utility to archive the DOS file space.

- Do not use Format/Configure Disk to format a DOS partition's file space.  Use an appropriate M/S-DOS or Windows utility to format the DOS file space.

- Do not store Distrix or Posix files on the DOS partition.  Posix and Distrix record information in the File Header Block associated with CTOS files, which is neither supported nor emulated on the DOS partition.

- The Executive Files command cannot display the contents of directories not in the root directory.  Nor can it display file details at any directory level.

- The SLIM service cannot read an NT file space formatted using NTFS format.  Only FAT partitions can be accessed.

- The SLIM service does not recognise or record NT unicode/long file names recorded in FAT directories.  The SLIM service can access these files by their ordinary 8.3 style name (displayed in the Windows NT file manager).

- The SLIM service cannot access Double-Space formatted DOS drives.

- CTOS cannot execute .Run files stored on the DOS partition.  This is due to the Paging Service, which requires direct access to the file system, thereby bypassing the SLIM service.  Such files must first be copied to the CTOS partition in order to be executed.


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How can you get a read/write version of the SLIM service?

First, try the read-only version of the SLIM service to see if it will work in your environment.  If you find that it works satisfactorily, contact SLIM as follows:

	Mark Emmerich
	SLIM
	10140 Firwood Drive
	Cupertino, CA  95014   USA
	(408)434-2626

Indicate that you would like information about the SLIM service and specify how to get in touch with you.  The cost is $20, ($28 if paid by foreign draft).  A 3.5" floppy diskette will be mailed along with instructions for use.

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