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PCTask_Tech.1
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PCTask_Tech.1
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1993-12-14
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7KB
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189 lines
PC-Task Technical Topics #1
by Justin Deeley
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Initialising and Formatting a SyQuest removable media
cartridge for use on the Amiga and MS-DOS machines, utilising
PC-Task and Cross-Dos
This document should aid in the preparing and formatting of
removable media hard disks for use as a transfer disk between the
Amiga and Macintosh or MS-Dos platforms.
Creating a hard disk partition for use with PC-Task is one
thing. Making this partition compatible with a real MS-Dos
machine is another. If you have set up any form of hard disk with
MS-Dos you will have discovered the joys of FDisk. This is to
MS-Dos what HDToolBox is to the Amiga. It writes the partition
information to the drive. On the Amiga, this is in the form of
Commodore's standard Rigid Disk Block (RDB).
Whilst AmigaDos's RDB's occupy the first 2 cylinders of a
given hard disk, MS-Dos uses a different method. Thus installing
RDB's on a disk that is to be used as an MS-Dos device on another
(non-Amiga) machine will render the disk useless. Enter PC-Task,
Cross-Dos and the dreaded mountlist!
Any device that is listed when the "info" command is used, is
"mounted". Most Amiga hard disk controllers auto-mount drives
which contain RDB's. However, when a hard disk, or controller,
does not contain or support RDB's, a mountlist is required. This
is a file either called "mountlist" found in the devs: drawer
(1-2-2.04), or as a file names the same as the required device
name in "devs:dosdrivers/" (2.1 ->).
The mountlist contains the relevant information required to
tell AmigaDos the specifications of the partition being mounted.
This consists of the filesystem being used, the dostype, the
actual drive geometry and so on.
As we are trying to use the hard disk with an MS-Dos format on
the Amiga, we require Cross-Dos. This is a commercial product,
that allows the reading and writing of MS-Dos formatted disks
(both floppy and hard) transparently from within AmigaDos.
Cross-Dos is available separately, or included with AmigaDos 2.1
or later. The documentation on Cross-Dos and hard disks in the
AmigaDos 3.0 manual is very slim , and the Cross-Dos manual is not
much better. Trial, error and the experience of others seems the
best way to learn anything about it.
Cross-Dos has some interesting quirks, one being that when you
give Cross-Dos the drive geometry, it will look for the first
MS-Dos partition, and change the geometry you set to match this.
PC-Task requires the actual drive geometry, and so we must not use
the CrossDosFileSystem with PC-Task when we Fdisk and format the
drive. If we just use Cross-Dos, the disk may appear to format
ok, but will be unreadable on an MS-Dos machine because the
information written by FDisk will not be present.
In order to get the right drive geometry, I suggest you use
HDToolBox on the Amiga. When the program is run, it will scan the
SCSI bus to find any attached devices. Click on the device that
you wish to format, and select "Change Drive Type". Select
"Define New" and then "Read Configuration". You will need to
write down the number of Heads, Cylinders and BlocksPerTrack.
When you have written this down simply "cancel" and "exit" the
program. Do NOT save the changes to the drive!
These numbers can then be placed into a mountlist. The
following is a mountlist for use with PC-Task only. It is for a
44MB SyQuest cartridge and the cartridge is 100% readable on real
MS-Dos machines, and Macintosh systems running "AccessPC".
PCD:
Device = <your scsi device>
Unit = <your unit number>
Flags = 0
Surfaces = 1
blocksPerTrack = 34
LowCyl = 0
HighCyl = 2549
DosType = 0x4d534800
#
Simply insert this into your mountlist file and type "mount
pcd:". This will make AmigaDos aware of the drive, but you will
not be able to access the drive PCD: from AmigaDos at all.
Now boot up PC-Task and specify PCD: as one of the hard
drives at the options screen. You will have to boot from an
MS-Dos floppy that has the system installed on it and the Fdisk
and Format commands present. One point to also note is that with
versions of MS-Dos below 4.0, the maximum size a hard disk could
be formatted to was 33 MB.
Once MS-Dos has booted off floppy, run the Fdisk program. You
will be presented with several options. It is best to simply
press return with each one. When the partition information has
been written, PC-Task will reboot MS-Dos from the floppy. When
you are presented with the prompt, type "format c: /s". You will
be asked to confirm this choice. Simply press "y" and return.
This will format the drive and make the drive bootable under
MS-Dos. You should now be able to remove the floppy and reboot
PC-Task with Ctrl-Alt-Del. You should be booted up to the system
prompt from the hard disk.
You can now read from and write to and from the hard disk with
PC-Task, but this is very awkward. If for instance, you wish to
place a picture you have on an Amiga partition, on an MS-Dos
formatted SyQuest cartridge in order to be printed out at an
output bureau. This is where Cross-Dos comes in. We require
another mountlist, that gives our device a filesystem to use under
AmigaDos. Below is a mountlist entry for a 44MB SyQuest
cartridge.
PCC:
FileSystem = L:CrossDOSFileSystem
Device = <your scsi device>
Unit = <your unit number>
Flags = 0
Surfaces = 1
blocksPerTrack = 34
LowCyl = 0
HighCyl = 2549
Buffers = 5
BufMemType = 1
StackSize = 600
Priority = 5
GlobVec = -1
DosType = 0x4d534800
#
When this device is mounted, you will be able to read and
write to the device just like any AmigaDos partition. Its simply
a matter of using a CLI or a directory utility like DirWork to
copy any needed files across.
WARNING: You MUST not write to a disk using Cross-Dos and
PC-Task at the same time, as the filesystems do not talk to each
other. You could end up with both programs trying to write to the
same place!
In order to use another size device, all that needs to be
changed are the Surfaces (equivalent to the number of heads),
blockspertrack, and the highcyl (the number of cylinders -1). A
mountlist for an 88MB SyQuest cartridge for Cross-Dos would be :
PCC:
FileSystem = L:CrossDOSFileSystem
Device = <your scsi device>
Unit = <your unit number>
Flags = 0
Surfaces = 1
blocksPerTrack = 64
LowCyl = 0
HighCyl = 2709
Buffers = 5
BufMemType = 1
StackSize = 600
Priority = 5
GlobVec = -1
DosType = 0x4d534800
#
and for PC-Task would be:
PCD:
Device = <your scsi device>
Unit = <your unit number>
Flags = 0
Surfaces = 1
blocksPerTrack = 64
LowCyl = 0
HighCyl = 2709
DosType = 0x4d534800
#
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