This driver was written without the cooperation of Iomega and without
any specifications for the hardware. Instead, I used a modified version
of the DOS emulator to capture all the parallel port traffic between
the DOS driver and the ZIP drive. From that I derived a model of the
protocol used and implemented this driver.
The ZIP drive is actually a SCSI device with a parallel to SCSI converter
built in. Iomega also sells that converter separately and this driver
*may* also work for that device. I don't have one and haven't tried it.
To try this driver you will need either a 1.2.13 or 1.3.37 Linux kernel.
Other versions might work, but those are the two that I have used in
developing the driver. You should also have support for SCSI disks in the
kernel (either built in or loaded as modules). You should not have PLIP
or LP support in the kernel. And, of course, you will need a parallel
port ZIP drive.
I have tested the driver on 'standard', bi-directional, EPP and ECP
parallel ports. It does not (yet) take advantage of any of the higher
performance capabilities of EPP or ECP, but it should adapt to 4 or 8 bit
transfers depending on the port. I've tested it on a slowish 486SX/33
and on a 486DX4/100. I have NOT tested it on an ELF system.
I've been able to read and write MS-DOS disks partitioned by Iomega's
software and I've also been able to use fdisk and mke2fs to build native
Linux file systems. Performance is not outstanding - but you wouldn't
expect that from a parallel port interface. In 8-bit mode, reads run at
approximately 100 kb/sec.
The source code for the driver, ppa.c, can be obtained by anonymous FTP
from /pub on gear.torque.net. Instructions for compiling and installing
the driver are included in the comments. If you are using 1.3.37 please
pay careful attention to the remarks about PROC_SCSI_PPA.
If you do try it out, please keep me posted on your successes and failures.
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Grant R. Guenther grant@torque.net
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