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SWAPSCSI 11/20/89
Enclosed is the first issue of 'SWAPSCSI', an added Basic.System
(ProDOS 8) command that allows the user to swap logical drives
(volumes) around on a given _REV C_ Apple SCSI card. It can only
be used with the Rev C Apple SCSI card, and provides a means for
Apple ProDOS 8 users to access other volumes on a hard drive with
more than two partitions. Only two volumes can be active at one
time in any given slot, but by swapping drive 1 or 2 with other
'drives', it's possible to easily access any volume on the disk
and manipulate it individually or in conjunction with any of the
other volumes. And a 'ReInit' is available to save the befuddled
user. This is how it works:
Add the command to ProDOS by BRUNing SWAPSCSI or -SWAPSCSI. This
installs the new command into Basic.System for ProDOS. It is
important to note that this is not a stand alone routine. It is
a user addition to Basic.System, like Glen Bredon's ProCommand
package. However, once the user has made any desired changes to
the volumes, he can leave Basic.System, and the changes will
remain in place until he turns his computer off or somehow
reINITs the SCSI card. Besides allowing the user to swap any two
SCSI 'drives' with one another, this command also provides a
means to INIT the SCSI card, so that it is easy to return all the
volume info to its standard setup.
After installation, the command syntax is as follows:
PRINT CHR$(4)"SWAP SCSI D1,D2"
swaps drive 1 with drive 2. Note that spaces are not important
and can be added to the command for clarity. If no slot is
specified, the default slot will be used per the user's last
callout.
PRINT CHR$(4)"SWAPSCSID1,D3;D2,D4"
swaps drive 1 with drive 3 and drive 2 with drive 4. See that
multiple swaps can be performed by separating them with a
semicolon.
SWAP SCSI D2,D7;S6
sets slot 6 and swaps drive 2 with drive 7, showing that the user
can set the slot as shown and can use the command in immediate
mode.
SWAP SCSI D1,D1
shows a special feature. If the user swaps a drive into itself
the command will reINIT the SCSI card in that slot, putting
things back to where they started from, just in case the user
gets confused. :)
SWAP SCSI D1,D1;D2,D6
of course the D1,D1 can be used just to make sure that the
desired swap is starting from a known condition.
As part of the command, the ProDOS bitmap is marked to show that
the pages of this command are in use. The command can be cleared
out by rerunning the Basic.System module. The SWAPSCSI command
BRUNs from location $6000, installing itself below any other pre-
existing ProDOS commands. Actually, SWAPSCSI is fully
relocatable, and can be run from any location that the user
desires. It is important that it be installed right at the
beginning of any BASIC program, because it would probably
overwrite any string variables that the user may have created in
his BASIC program. It can be installed in the immediate as
well as the deferred mode.
I've used the command for a while, and it seems to be fairly
solid, but if anyone runs into a problem, please let me know at
C.PETERSON5. This is not a commercial product, so exercise
reasonable care until you get confidence in it. It should be of
most benefit to those folks who work primarily in a ProDOS 8
environment. Cheers.
Craig Peterson :-)}