Q: PCMCIA SCSI and parallel port

Q: PCMCIA SCSI and parallel port

Post by Lian She » Wed, 29 Apr 1998 04:00:00



Hi, Linux users,

I want to choose a backup drive. The SyQuest's SparQ or SyJet and the
Iomega's Jaz drive come for considering.

The problem is, I don't know if I should buy the parallel version or the
SCSI version.

For the parallel version, I heard it's very slow (someone claims a speed
of 8MB/min).
For the SCSI version I need to buy a PCMCIA SCSI card, like the
Adaptec's SlimSCSI 1460 or 1480. 1460 is 16bit version, 1480 is of
32bit; accordingly 1460 offers only 2MB/sec, 1480 about 130MB/sec
transfer rate (the data is from Adaptec). But currently the 1480 is not
supported by Linux, I even don't know if it will be supported at all in
the future.

Can someone tell me real life experience about the SlimSCSI transfer
rate between internal harddrive and external drive? Further if someone
has just data about parallel version, I'd like to have too.

I wonder if the transfer rate with SlimSCSI 1460 is only just comparable
with parallel version.

Thanks in advance!

lian

--
------

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
| Lian Shen                                Math Ph.D. student  |
| Swiss Federal Institute of Technology, Zurich  ETHZ, CH-8092 |
|                                                              |
| "God is a mathematician of very high order, and he used very |
| advanced mathematics in constructing the universe."  (Dirac) |
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

 
 
 

Q: PCMCIA SCSI and parallel port

Post by David Hin » Wed, 29 Apr 1998 04:00:00


: Hi, Linux users,
:
: I want to choose a backup drive. The SyQuest's SparQ or SyJet and the
: Iomega's Jaz drive come for considering.
:
: The problem is, I don't know if I should buy the parallel version or the
: SCSI version.
:
: For the parallel version, I heard it's very slow (someone claims a speed
: of 8MB/min).
: For the SCSI version I need to buy a PCMCIA SCSI card, like the
: Adaptec's SlimSCSI 1460 or 1480. 1460 is 16bit version, 1480 is of
: 32bit; accordingly 1460 offers only 2MB/sec, 1480 about 130MB/sec
: transfer rate (the data is from Adaptec). But currently the 1480 is not
: supported by Linux, I even don't know if it will be supported at all in
: the future.

The Adaptec 1480 is supported by the latest beta PCMCIA package.

The SlimSCSI 1460 does about 2 MB/sec, as you said.  The 1480 will do
more, if your device can do more.  Don't expect anything remotely
resembling 130 MB/sec from it.

Syquest claims that they can get 1.25 MB/sec, sustained, with the
parallel port drives.  I've also heard reports that were much slower.
I don't know if that's due to problems in the Linux driver, or
differences in parallel port hardware.

-- Dave Hinds

 
 
 

1. Some Qs about parallel port programming (in EPP mode)

Hi all,

I am a newie in Linux device driver programming. I need to write a
parallel port driver in EPP mode and have read the parallel port
spec. in the past two weeks. However, I still get confused and hope
for the help.

1. Is it right that I just write/read the PARPORT_PORT_BASE+4, the
   hardware will do the EPP handshake itself and transfer the data?
   If not, any bits in the register I need to (de)active?

2. I have read lp.c in Linux Kernel Source and found the following
   code. Why it use do { ... } while (0) to enclose the actual code?

   #define w_dtr(x,y)  \
    do { parport_write_data(lp_table[(x)].dev->port, (y)); } while (0)

3. Have any web sites discuss how to program the parallel port driver
   in EPP mode?

Thanks for any help.

Sent via Deja.com http://www.deja.com/
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