View Full Version : Quantum Fireball 1280, TMC-870 and SCSI parity

March 18th, 2011, 01:01 PM
Hi guys,

I am still trying to get as much as possible from SCSI interface for my 8088 XT clone.
Once I have successfully set-up FutureDomain TMC-870 controller, I start looking for a HDD larger than 80 meg Seagate I currently have.
Recently, I have obtained a Quantum Fireball 1280s SCSI drive: http://stason.org/TULARC/pc/hard-drives-hdd/quantum/FIREBALL-1280S-1281MB-3-5-SL-SCSI2-3-SE.html.
When I plugged it in, nothing worked, of course :)
The problem is that my TMC-870 does not work with devices whose SCSI parity is enabled. This has been proved experimentally. Usually, a SCSI device has a jumper that controls parity and opening it solves the problem. So was for my Seagate HDD and CD-ROM. But this Quantum HDD does not have a parity jumper. The parity is software controlled through SCSI mode pages, as it is said in specs. And it is turned ON by default.
What is funny, when I attached this HDD to ST-01B controller, it worked fine! But, anyway, I need to make it work with TMC-870, which means I need to turn off the parity.
I tried all SCSI HDD utilities I could find:

Quantum Disk Manager
Maxtor PowerMax
Seagate SeaTools

but neiher of them provided an access to parity setting.
At last, I located a "SDPARM" command line utility, using which I am able to change different bits in the SCSI mode pages. Exploring SCSI parameters of the HDD revealed the following:
There is no page 29h as described in the spec - only 9h and 39h.
Each of the previously mentioned vendor-specific pages has its own set of bytes:
PG09: 89-0E-00-00-00-00-00-00-00-00-00-00-00-00-01-04
PG39: B9-06-10-00-00-00-00-00
Unfortunately, I have no idea where is the parity control in these data structures.
I tried to set bytes, marked with red, to 0, but nothing happened.
My questions are:

Does anybody know if there is an utility for Quantum which can help with vendor-specific settings?
Or, maybe, there is an idea which bytes can I change to disable parity? Technically, I can fill all vendor-specific pages whih 0s, but I'm not sure that HDD will survive such an experiment.
FutureDomain TMC-870 not suppotring parity - is it a bug or a feature? (BIOS version 4.0L)

June 23rd, 2011, 12:11 PM
The problem was solved, thanks to Seagate support forums. The parity control bit appeared on page 0x39, byte 4, bit 2. It should be set to disable parity.