ZIP-drive mini-HOWTO: Frequently asked questions

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These are some of the questions that we get asked a lot. Please read the answers here before asking them again !

5.1 Can I boot from the ZIP drive ?

This depends on what you are using for a host adapter. If your host adapter has a BIOS ROM with code that can boot from target 5 or 6, then yes, you can boot from the SCSI ZIP drive. You cannot boot from a parallel port drive.

If you have DOS on your main disk and want to boot Linux from a ZIP disk, you can do this using the LOADLIN boot loader. Your kernel image must be somewhere on the DOS disk, but the rest of your Linux system could be on the ZIP. Make sure that the kernel you use has the correct drivers built in.

As far as I am aware, there are no installation boot floppies for any of the popular distributions that contain the parallel ZIP driver, but this may change when Linux 2.0 comes out.

5.2 Why does Iomega use partition number 4 ?

This is one of the most popular questions, but I don’t think anyone has a definite answer to this one. Maybe there is no good reason.

5.3 How can I have the disk mounted at boot time ?

All you need to do is to add a line to your /etc/fstab file. For instance, if you will always have a DOS disk in the drive when you boot, you could put


/dev/sda4   /zip  msdos  defaults  0 0

in the fstab. Depending on your distribution, the initialisation scripts might try to run fsck on partitions listed in your fstab. Be aware that this could cause problems if you forget to put the disk in the drive when you boot, or have the wrong disk there.

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5.4 What happens if there is no disk inserted when I boot ?

The kernel will try to read the partition table, but the operation will time out. There is nothing to worry about. Once you have inserted a disk, and try to do something with it the kernel will notice that there is a disk there now and rescan the partition table.

HINT: when you change disks, it is a good idea always to use fdisk to check the partition structure on the new disk.

The BIOS on some SCSI host adapters will attempt to read the partition table on your disk during the system boot. If you cannot disable this check, you may be forced always to boot with a disk in the drive.

5.5 What SCSI adapters are compatible with the ZIP drive ?

Iomega has a list of compatible host adapters at:

http://www.iomega.com/techs/zip/what063.html

5.6 Can I use the parallel drive as a real SCSI disk ?

The PPA-3 parallel-to-SCSI adapter is implemented as a single ASIC chip that Iomega calls a VPI0. It is embedded on the ZIP drive’s controller card. There is an actual SCSI bus present, but not in a useful form.

Although I haven’t tried to compare the two cards, it seems logical that the VPI0 replaces the conventional electrical buffering circuits that would be required if the SCSI bus were extended outside the package.

5.7 Can I plug a printer into the parallel drive ?

Yes, but. Currently, you cannot have both the lp and ppa drivers active on the same parallel port. A resource sharing protocol has been designed and is in the early stages of implementation, but will not be available before Linux 2.0 is released.

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In the meantime, if you do chain a printer and a ZIP drive, you can use them both without rebooting your system, providing you have built the lp and ppa drivers as loadable modules. If you have done so, then when you want to print you would insmod the lp driver, and when you want to access the ZIP drive you would load the ppa driver.

Of course, if you have two parallel ports, you can use one for printing and one for your ZIP drive. Just build a kernel with both the lp and ppa drivers included, then put some appropriate configuration commands on your kernel command line. For instance, if you use LILO and you have a printer on 0x378 and a ZIP drive at 0x3bc you could add the following line to your /etc/lilo.conf file.


append = "lp=0x378 ppa=0x3bc"

5.8 Do you plan to support EPP/ECP ports in PPA ?

ppa was initially developed without the benefit of any technical specifications for the command protocol on the parallel bus. Instead, the DOS emulator was used to gather information to reverse engineer the protocol. It was not possible to get the drive to work in an enhanced mode under the emulator.

An Iomega technical reference manual is now available, and I have located a data sheet for an enhanced parallel port chip, so it may be possible to upgrade the driver.

5.9 Can PPA be used with Iomega’s parallel port tape drives ?

No. Those drives are floppy-tape drives, there is no SCSI involved.

Several people have indicated an interest in applying my methods to try to determine the protocol and develop a driver for these tapes. The first step in that process is to get the DOS driver working under DOSemu. I have not yet heard that anyone has been successful in doing it.

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5.10 Will PPA work with the parallel port SyQuest EZ135 ?

No. The EZ135 is an IDE drive with a ShuttlePort parallel to IDE converter embedded in it.

Work has begun on decoding the protocol with the intention of writing a Linux driver for the parallel port EZ135. I have the basic protocol worked out, but I have no idea when a driver might be completed.

Keep an eye on my web page, I will eventually be looking for some beta testers.

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