Date: Wed, 5 Jan 2000 20:37:54 -0600 (CST) From: Acadix Software Systems <acadix@execpc.com> To: freebsd-doc@freebsd.org Subject: ZIP Drive doc for handbook Message-ID: <Pine.SOL.4.10.10001052021200.11292-200000@earth.execpc.com>
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[-- Attachment #1 --]
Hello ladies and gentlemen,
I just went through some major pains getting my parallel port ZIP drive
to work under FreeBSD 3.2. As it turns out, I seem to have hit every
possible contingency ( My system has a SCSI root disk that had to be
wired down to prevent the ZIP from becoming the root device, an ATAPI
cdrom that seems to be broke, and my ZIP drive is attached to a second
parallel port that had an IRQ conflict with sio2 ) As a result, I've
learned quite a bit from reconfiguring my kernel about 20 times (mainly
because I thought I had screwed up the cdrom config), and I
thought I'd better document the experience before my emotional defense
mechanisms step in and block out all memories of the incident.
(Sounds a bit like the life of George Costanza, doesn't it?)
Anyway, I wrote up an HTML doc covering everything I know about ZIP
drives under FreeBSD, and you're welcome to use it in the handbook if you
like. Let me know if you think it needs any tweaking to fit in.
Cheers,
-Jason
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<html>
<head><title>Parallel ZIP Drives</title></head>
<body>
<blockquote>
<h1>ZIP Drive Basics</h1>
ZIP disks are high capacity, removable, magnetic disks, which can be
read or written by ZIP drives from iomega corporation.
ZIP disks are similar to floppy disks, except that they
are much faster, and have a much greater capacity. While floppy
disks typically hold 1.44 megabytes, ZIP disks are available in
two sizes, namely 100 megabytes and 250 megabytes.
ZIP drives should not be confused with the <a href=>super-floppy</a>,
a 120 megabyte floppy drive which also handles traditional 1.44
megabyte floppies.
IOMEGA also sells a higher capacity, higher performance drive
called the JAZZ drive. JAZZ drives come in 1 gigabyte and
2 gigabyte sizes.
<p>
ZIP drives are available as internal or external units, using one
of three interfaces:
<p>
<! Unordered list of >
<UL>
<LI>The SCSI (Small Computer Standard Interface) interface is
the fastest, most sophisticated, most expandable, and most expensive
interface. The SCSI interface is used by all types of computers
from PC's to RISC workstations to minicomputers,
to connect all types of peripherals such as disk drives, tape
drives, scanners, and so on.
SCSI ZIP drives may be internal or external, assuming your host
adapter has an external connector.
<blockquote>
<em>Note: If you are using an external SCSI device, it is
important never to connect or disconnect it from the SCSI
bus while the computer is running. Doing so may cause
file-system damage on the disks that remain connected.</em>
</blockquote>
If you want maximum performance and easy setup, the SCSI interface
is the best choice. This will probably require adding a SCSI host
adapter, since most PC's (except for high-performance servers)
don't have built-in SCSI support. Each SCSI host adapter can support
either 7 or 15 SCSI devices, depending on the model.
<p>
Each SCSI
device has it's own controller, and these controllers are fairly
intelligent and
well standardized, (the second `S' in SCSI is for Standard) so
from the operating system's point of view, all SCSI disk drives
look about the same, as do all SCSI tape drives, etc. To support
SCSI devices, the operating system need only have a driver for
the particular host adapter, and a generic driver for each type
of device, i.e. a SCSI disk driver, SCSI tape driver, and so
on. There are some SCSI devices that can be better utilized
with specialized drivers (e.g. DAT tape drives), but they
tend to work OK with the generic driver, too. It's just that the
generic drivers may not support some of the special features.
<p>
Using a SCSI zip drive is simply a matter of determining which
device file in the /dev directory represents the ZIP drive.
This can be determined by looking at the boot messages while
FreeBSD is booting (or in /var/log/messages after booting),
where you'll see a line something like this:
<blockquote>
da1: <IOMEGA ZIP 100 D.13> Removable Direct Access SCSI-2 Device
</blockquote>
This means that the ZIP drive is represented by the file /dev/da1.
<p>
<LI>The IDE (Integrated Drive Electronics) interface is a low-cost
disk drive interface used by many desktop PC's. Most IDE
devices are strictly internal.
<p>
Performance of IDE ZIP drives is comparable to SCSI ZIP
drives. ( The IDE interface is not as fast as SCSI, but
ZIP drives performance is limited mainly by the mechanics of the
drive, not by the bus interface. )
<p>
The drawback of the IDE interface is the limitations it
imposes. Most IDE adapters can only support 2 devices, and
IDE interfaces are not typically designed for the long term.
For example, the original IDE interface would not support
hard disks with more than 1024 cylinders, which forced a lot
of people to upgrade their hardware prematurely. If you
have plans to expand your PC by adding another disk, a tape
drive, or scanner, you may want to invest in a SCSI host
adapter and a SCSI ZIP drive to avoid problems in the future.
<p>
IDE devices in FreeBSD are prefixed with a "w". For example,
an IDE hard disk might be /dev/wd0, an IDE (ATAPI) cdrom
might be /dev/wcd1, and so on.
<p>
<LI>The parallel port interface is popular for portable external
devices such as external ZIP drives and scanners, because
virtually every computer has a standard parallel port (usually
used for printers). This makes things easy for people to transfer
data between multiple computers by toting around their
ZIP drive.
<p>
Performance will generally be slower than a SCSI or IDE ZIP
drive, since it is limited by the speed of the parallel port.
Parallel port speed varies considerably between various computers,
and can often be configured in the system BIOS. Some machines
will also require BIOS configuration to operate the parallel
port in bidirectional mode. ( Parallel ports were originally
designed only for output to printers )
</UL>
<h1>Parallel ZIP: The vpo Driver</h1>
To use a parallel-port ZIP drive under FreeBSD, the <em>vpo</em>
driver must be configured into the kernel. Parallel port ZIP
drives also have a built-in SCSI controller.
The vpo driver allows
the FreeBSD kernel to communicate with the ZIP drive's SCSI controller
through the parallel port.
<p>
Since the vpo driver is not a standard part of the kernel (as of
FreeBSD 3.2), you will need to rebuild the kernel to enable this
device. The process of building a kernel is outlined in detail
in another section. The following steps outline the process in
brief for the purpose of enabling the vpo driver:
<p>
<! Ordered list of >
<OL>
<LI>Run /stand/sysinstall, and install the kernel source code
on your system.
<p>
<LI>cd /sys/i386/conf
<p>
<LI>cp GENERIC MYKERNEL
<p>
<LI>Edit MYKERNEL, change the "ident" line to MYKERNEL,
and uncomment the line describing the vpo driver.
<p>
If you have a second parallel port, you may need to copy the
section for ppc0 to create a ppc1 device. The second parallel
port usually uses IRQ 5 and address 378. Only the IRQ is required
in the config file.
<p>
If you're root hard disk is a SCSI disk, you might run
into a problem with probing order, which will cause the system
to attempt to use the ZIP drive as the root device. This will
cause a boot failure, unless you happen to have a FreeBSD root
file-system on your ZIP disk! In this case, you will need to
"wire down" the root disk, i.e. force the kernel to bind a
specific device to /dev/da0, the root SCSI disk. It will then assign
the ZIP disk to the next available SCSI disk, e.g. /dev/da1.
To wire down your SCSI hard drive as da0, change the line
<blockquote>
device da0
</blockquote>
to
<blockquote>
disk da0 at scbus0 target 0 unit 0
</blockquote>
You may need to change the target above to match the SCSI ID of your
disk drive.
You should also wire down the scbus0 entry to your
controller. For example, if you have an Adaptec 15xx controller,
you would change
<blockquote>
controller scbus0
</blockquote>
to
<blockquote>
controller scbus0 at aha0
</blockquote>
Lastly, as long as you're editing the kernel config, you
can take the opportunity to remove all the unnecessary drivers.
This should be done with a great deal of caution, and only if
you feel confident about making kernel modifications.
Removing unnecessary drivers will reduce the kernel size,
leaving more memory available for your applications. To determine
which drivers are not needed, go to the end of the file
/var/log/messages, and look for lines reading "not found".
Then, comment out these devices in your config file.
You can also change other options to reduce the size and increase
the speed of your kernel.
Read the section on rebuilding your kernel for more
complete information.
<p>
<LI>Now it's time to compile the kernel:
<p>
<! Ordered list of >
<OL>
<LI>/usr/sbin/config MYKERNEL
<LI>cd ../../compile/MYKERNEL
<LI>make depend
<LI>make
<LI>make install
</OL>
</OL>
<p>
After the kernel is rebuilt, you'll need to reboot. Make sure the
ZIP drive is connected to the parallel port before the boot begins.
You should see the ZIP drive show up in the boot messages as device
vpo0 or vpo1, depending on which parallel port the drive is attached
to. It should also show which device file the ZIP drive has been
bound to. This will be /dev/da0 if you have no other SCSI disks
in the system, or /dev/da1 if you have a SCSI hard disk wired down
as the root device.
<h1>Mounting ZIP disks</h1>
To access the ZIP disk, you simply mount it like any other disk device.
The file-system is represented as slice 4 on the device, so for SCSI
or parallel ZIP disks, you would use
<blockquote>
mount_msdos /dev/da1s4 /mnt
</blockquote>
For IDE ZIP drives, use
<blockquote>
mount_msdos /dev/wd1s4 /mnt
</blockquote>
It will also be helpful to update /etc/fstab to make mounting easier.
Add a line like the following, edited to suit your system:
<blockquote>
/dev/da1s4 /zip msdos rw,noauto 0 0
</blockquote>
and create the directory /zip.
Then, you can mount simply by typing
<blockquote>
mount /zip
</blockquote>
and unmount by typing
<blockquote>
umount /zip
</blockquote>
For more information on the format of /etc/fstab, run "man fstab".
<p>
You can also create a FreeBSD file-system on the ZIP disk
using mkfs. However, the disk will only be usable on a FreeBSD
system, or perhaps a few other Unix clones that recognize FreeBSD
file-systems. ( Definitely not DOS or Windows )
<h1>Author</h1>
This document was written by:
<blockquote>
Jason W. Bacon<br>
info@acadix.com<br>
jbacon@mcw.edu<br>
bacon@cs.uwm.edu<br>
</blockquote>
Questions and comments regarding this document are welcome.
<p>
Disclaimer:
<p>
I have no affiliation with the FreeBSD organization, iomega,
or the author(s) of the vpo driver. ( I'm just a guy with a ZIP
drive and hopes of making life a little easier for other FreeBSD
users. ) Good luck, and enjoy!
</blockquote>
</body>
</html>
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