From: udo@umunk.GUN.de (Udo Munk)
Newsgroups: comp.os.coherent
Distribution: world
Subject: Re: Coherent v4 SCSI and ST-506
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Organization: Udo Munk's private BBS
Date: Wed, 23 Dec 92 19:36:43 GMT

Michael Faurot (mfaurot@bogart.uucp) wrote:
: A few questions here concerning SCSI and Coherent.  I'm currently
: running v4 with an ST-506 (RLL) controller and I installed Coherent with
: only this support.  I'm thinking about getting a SCSI host adapter
: sometime within the future, probably an Adaptec 1542b.
: 
: 1)	I recall when doing the install, that the installation program
: 	prompts whether you wish to use an AT style controller
: 	(ST-506, ESDI and IDE), a SCSI or both.  Is anyone running
: 	Coherent with both an ST-506 controller and a SCSI controller?
: 	If yes, what type SCSI controller (vendor and model #).  Which
: 	controller does the system boot from?  Which controller is
: 	controlling your floppy drives?  

	1 WD 1006V-MM2 compatible interleave 1:1 controller with
	2 Seagate ST-251 40MB hard disks, this controller also
	controlls the floppy disks (5,25" and 3,5")
	1 Future Domain TMC-885 SCSI controller
	1 Maxtor 7120S 120MB hard disk

: 2)      Assuming that it is possible to use both an ST-506
: 	controller and a SCSI controller in the same machine with
: 	Coherent concurrently, which SCSI controller is best to use if
: 	you are not able to alter the ST-506's configuration (ie.,
: 	you're not able to disable the floppy support and/or must boot
: 	from the ST-506)?

	It's no question, the Adaptec AH-1542 SCSI controller is the
	best one available today for ISA bus systems. But be warned,
	this controller uses busmaster DMA and has problems with
	some motherboards. The problem is that you are losing characters
	on the serial lines when there is heavy disk I/O. This problem
	does not occur only under COHERENT, I've heared from others
	that they have problems with SCO and Interactive too.
	Also with the current COHERENT driver for the AHA it's not
	possible to patch the bus-on bus-off times for the busmaster
	DMA. All SCSI controller which comes with a floppy port allows
	to disable it with a jumper, so you woun't have problems with
	the floppy controller from your ST-506. Also you could buy
	the version without the floppy controller. I bought one with,
	because later I'll remove the whole ST-506 hardware, you
	should think about what you want to do in the future.

: 3)	I currently need to run Coherent with alternative polling
: 	so that it properly accesses my ST-506 controller.  What, if
: 	any, impact will this have on the SCSI end of things if both
: 	SCSI and ST-506 can exist together?

	The polling hasn't anything to do with the SCSI driver.

: 4)	How does one go about adding in SCSI support after the system
: 	is already installed?  Obviously the various device files
: 	need to be created, the kernel probably needs to be updated
: 	etc.  I know I could get this done by re-installing, but that
: 	is an unacceptable solution (IMO).

	Right, add the drive to your BIOS if it's your secound one.
	You have to build a new kernel which contains one of the
	SCSI drivers (ss or ah). This is very easy with the DDK,
	without it's a greater problem, ask MWC about that if you
	don't have the DDK.
	Then patch your new kernel as explained in the manual (SCSI)
	and create the device nodes eigther manually or with mkdev scsi.
	Boot the new kernel and run fdisk -c /dev/sd0x to
	create the partitions on your new disk. If the disk has more
	then 1024 cylinders or the driver reports wrong parameters
	for the disk use /etc/hdparms before, to change them.

: 5)	Any comments or tips on using Adaptec SCSI controllers with 
: 	Coherent either in conjunction with another type controller or
: 	used alone?  Any recommended IRQ, DMA, jumper settings etc.? 
: 	Any particular model number that's best suited for use with
: 	Coherent over another, or one to particularly avoid?  Any
: 	versions of the firmware on board to look for over another?

	Hm, I got the TMC-885 because I like a somewhat slower
	system thats works without problems more, then a super duper
	highspeed system with some problems. If you really want to
	get an Adaptec I would suggest to wait until MWC has fixed
	the driver. The IRQ, DMA, memory address used by the controller
	and jumper setting are very system specific, you have to find
	a working configuration by your selfe. The model depends on
	if you want to have the floppy port or not. Buy the latest
	version, AHA-1542 or TMC-885. I haven't heared about needings
	of special firmware if you want to run hard disks and tapes
	only. The real trouble begins if you try to get a CD-ROM,
	WORM, scanner or printer running ;-)

	I needed one day to get mine running, good luck.
--
Udo Munk, Oberstr. 21, 4040 Neuss 1, Germany
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Newsgroups: comp.os.coherent