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February 2001

Dawicontrol DC-2976UW SCSI Controller

By Thomas Klein December 2000

Price: Approx. 199 German Marks (approx. 100,00 Euro / 97.00 US-$)
Dawicontrol Homepage: http://www.dawicontrol.de
LSI Logic Homepage: http://www.lsilogic.com
Device Driver Fixpak2: ftp://ftp.software.ibm.com/ps/products/os2/fixes/ddpak/xr_d002/
JJSCDROM.DMD: ftp://ftp.leo.org/pub/comp/os/os2/leo/drivers/cdrom/jjscdrom_20000711.zip

During the past few years, I met a lot of people who have decided to use SCSI systems at home due to their familiarity with them in their professional environment. I have to admit that they are in a minority, but on the other hand they all believe and trust in the advantages of the concepts behind SCSI.

But when talking to them about SCSI at home, it's usually all about one single brand: Adaptec. I consider this to be a compliment regarding the outstanding quality of their products and drivers (and their Marketing as well), but we should not forget to point out the existence of other manufacturers as well, who provide alternate and quite interesting solutions. Today, I would like to introduce one of those manufacturers - Dawicontrol - by means of their UltraWide-SCSI3-PCI-Controller named DC-2976UW.

Made in Germany

Years ago (in the mid-80's I guess) there was a funny German TV show, that made a joke of this slogan by presenting a sleek luxury car of a well-known German brand (the one that merged with an American brand recently), wearing a fat banner "made in Germany" across the windshield. But with the camera closing in more and more, the audience could read a tiny "printed in Taiwan" on that banner.

Although I really loved that joke and I'm okay with the meaning behind it, I'm always quite disappointed when people are surprised to hear Dawicontrol is a German brand of SCSI controllers. Apparently "German hardware" nowadays means cars, tanks, washing machines and at least some bulky high-priced PC stuff... Now, Dawicontrol proves this to be wrong. 

By chance

Actually it was due to the breakdown of an Adaptec AHA-2940, that my attention focused on those products from Göttingen, and merely by chance that I encountered a DC-2974, an incredibly inexpensive PCI-SCSI-Controller, that seemed to have everything needed to replace the Adaptec model.

Now, as an OS/2 user, I always try to proceed carefully when there's a need for hardware. At least about drivers, you know.... But to my surprise their homepage stated that all products supported OS/2. I finally decided to give it a try and was not disappointed. After plugging in, attaching cables and editing CONFIG.SYS to use the new driver everything went as before (it really could have turned out different...).

Some years have passed since those days. Now it's a DC-2975U running my server, and the DC-2974 running my wife's workstation (at least until some weeks ago, when I needed it as a spare part). So I found it to be a good occasion that my Adaptec AHA-2940UW broke down just recently (why do they always simply do that?). Once more, I decided the next family member should be of Göttingen breed. 

On first sight

The OS/2 logo is shown on both the package and the quick reference. Nice to see it is still around.

The ecological-minded ones among you will certainly appreciate the fact, that no bubble-wrap, foam pads or other plastic material was used in the package - it consist entirely of paper, with the exception of the antistatic protection bag (inevitable!) and the shrink wrap around the box. I consider the latter to be necessary as some kind of seal, showing that the box contents are intact and complete.

Once unpacked, we find the box contains the controller, a printed quick reference, the driver disk and the two internal flat-ribbon cables (50-pin and 68-pin type).

Fig.1: Contents of the package

On second sight

The chip used on the DC-2976UW is a SYM53C875 by Symbios (who recently became "LSI Logic"). This is quite important for it gives us some useful possibilities regarding installation and operation as you'll see later in this article. The controller provides three connector plugs: Internally both 50-pin and 68-pin and an external 68-pin high density (HD) plug. Only two of them can be used together - this is due to the fact that the controller operates two buses and the principles of SCSI, placing the controller "electrically" in the middle of the SCSI chain. Attaching devices on each of the three connectors would result in a star-shaped SCSI topology... which equals: Trouble. This limitation sometimes is some kind of annoying but it's quite common on controllers of this class.

Fig.2: The controller board

Each of the two cables that come with the adapter provide three connectors. This means that you'll be able to attach two devices to each the 8-Bit bus (50-pin cable) and the 16-Bit bus (68-pin cable), as the third connector is used to be attached to the controller itself of course. This should be sufficient for most private users - those who own more devices certainly already own appropriate cables too. The DC-2976UW features two jumpers that are used to determine the termination settings of each of its two buses. These jumpers are factory-preset to Automatic, making the controller detect whether devices are attached and enabling/disabling termination for each bus accordingly.

I don't want to go into the principles of SCSI too deeply at this point. Just let me say that, yes, termination can be set to ON or OFF manually, but as far as I am concerned, automatic always worked for me until today, regardless of internal/external devices, configuration or manufacturer.

While reaching for the cordless screwdriver and puzzling whether it's kid or cat who's to blame for the loss of the Phillips tip, I happen to take a glance at the manual. Why did they change its name to "quick reference" and how comes it is much thinner than before? A single look at the contents page makes me know what has happened:
No sign of
OS/2 (and no sign of Linux or Novell either). Only Windows 95, 98, NT and 2000. Another look - now at the first page - clarifies the situation:

Fig.3: The stuff, quick references are made of

Fine but... too bad: There was no CD included in my box... and given the situation my PC would lie in pieces to my feet: How to access the Internet in that case, well?

Okay, okay - the drivers are included on the disk and we all know what to do, but troubles start here if you're new to SCSI or OS/2 (yes, I was told this still happens). I really don't understand this - I always had the memory of Dawicontrol being *the* example for good manuals... now look at this.

Well, I downloaded the PDF and it is as good as I remembered, but it would have been even better if I had found it in front of me, right after opening that box... like before... or on that cute CD which was not included (or even on a separate floppy disk as the PDF only takes up 245K).

Talking of floppies reminds me to mention that a lot of inexperienced SCSI-users consider their usage (instead of CD) as antiquated . Okay, but how do you access the drivers on a CD if you haven't got the drivers for that CD drive... any suggestions? Of course [sigh] there are ways and means to access the data without an additional PC and of course there are people without a floppy drive, but anyway: Floppies are best in this case. Hmm, this makes me think: What if *that* is the reason for this missing CD? ;)

Hardware setup

The "Dawi" plugs into the second PCI Slot, that already hosted it's predecessor - and fits perfectly. Even tightening the screw doesn't make it pull out of the slot - well done. (My computer's case apparently has proven to be some kind of reference device for this purpose).

I don't worry about IRQ's. As I don't have any IDE devices in that PC, I deactivated both on-board IDE controllers thus freeing their IRQ's. I can't stand plug and play (for a personal reason, but that's another story) so I manually assign resources. The AGP slot taken up by my Matrox G200 is assigned IRQ14, the 2nd PCI slot (used by the SCSI-Controller) is assigned IRQ 15.

This leaves only the internal cables to be attached to finish hardware stuff. I don't use a scanner with that PC. This allows me to use both internal connectors - just as with an Adaptec's 2940UW. There's only the ultra wide IBM disk attached to the 16Bit bus; all other devices connect to the 8Bit-cable: CD-Rom, CD-Writer, Streamer, Zip-Drive and second hard disk..

Termination was already correct on both cables before, so was the SCSI ID assignment, and as I didn't change a single thing of that I keep going on immediately...

First boot-up

Usually at boot time there's a moment after POST (power-on self test) where the system scans for IDE devices - this is now replaced with the messages from the SCSI controller appearing. Along with BIOS Version they contain information on the resources assigned like "my" IRQ15 and the ROM- and I/O-addresses which are set automatically. Like any other SCSI-Controller with a built-in BIOS, the DC-2976UW also shows a message on how to enter it's BIOS setup. While Adaptec prefers <ctrl-a> and Tekram uses <F2> or <F6>, the folks from Dawicontrol decided to let their controllers behave like the Phoenix' or AMI's BIOS and use the <del>-key instead.

If you don't enter BIOS setup, there's a 15 second delay next. This is done at each "real" power-on (not reset or ctrl-alt-del) and can be overridden by pressing the <esc>-key, as shown in the message on screen. Some older SCSI devices need additional time to gain a specific initial state (e.g. rotation speed), before they can be operated. Any activity before this point (like a bus scan) might result in erratic behaviour of such devices, thus leading to an increased duration of the scan or incomplete device list. This delay (so-called Power-On Wait feature) can be enabled/disabled in the controller's BIOS setup.

The bus scan doesn't quite provide a wealth of information to the user. It consists of the controller's own SCSI ID and a list of all devices having BIOS support at boot time. Each of these devices is displayed by SCSI ID, manufacturer and model name. For hard disks, you'll find the drive letter assigned by the controller's BIOS and the number of heads and sectors used by the controller to access the disk - that's all.

I can't tell whether there's a need to display additional information at this point, like for example about sync/async communication or maximal transfer rate of a device, since these features can be influenced by specifying appropriate device driver parameters at a later time - Dawicontrol doesn't provide this information anyway. Another point is the drive letter "assigned". I rather consider this to be some kind of visual representation whether a hard disk is supported and in which sequence... I would prefer disk number here, because as users of OS/2 we all know that strange things can happen to drive letters, depending on the operating system being loaded. ;)

Anyway - at this point it's the operating system being loaded. For me this means that it's the OS/2 boot manager appearing - a good occasion to take a closer look on one of the more important components of the controller: It's BIOS. 

Controller BIOS

As I already mentioned, the controller's BIOS provides a way of governing some of the controller's features. All hardware resources (IRQ, I/O-address, ROM-address) are being assigned automatically by means of plug-and-play-negotiation between the controller and the PC (between their BIOSes to be exactly). There's no way of changing this - except that you might assign an IRQ for the controller's slot manually in the PC's BIOS. One of the editable features is "Power-On Wait", which can be enabled or disabled - it's delay time however is fixed to 15 seconds.

The boot device can be selected by specifying it's SCSI ID. This is preset to SCSI-ID 0 which turns out to be the standard setting in SCSI world. You can also choose the SCSI-ID to be assigned to the adapter itself. It's default setting is "automatic" - in my case this turns out to be 7 - the "classic" SCSI Controller ID.

The BIOS supports bootable CD's, but I have to admit that I didn't check for that as I don't have such a CD. There's support to use removable disks as hard disks, but I didn't check that either, as well as support for multiple LUN's (multiple logical unit numbers - that's the case in a CD changer for example). So far the settings of the controller itself.

Up to 15 devices are supported. This will give you a maximum of 16 devices including the controller itself. Each device provides the following settings on the single BIOS setup screen (the default value of each setting is underlined):

BIOS support

yes / no

disconnect / reselect

yes / no

transfer method

automatic / sync / async

transfer width

automatic / 16-Bit / 8-Bit

maximum transfer rate (MB/sec.)

40 / 32 / 26 / 22 / 20 / 16 / 13 / 11 / 10 / 8 / 7 / 6 / 5 / 4 / 3 / 2 (> 20 if transfer with set to "automatic" or 16-Bit)

Setting BIOS support to "no" will result in the specific device being invisible to accesses through interrupt 13h at boot time of the operating system. This changes when the controller's driver is being loaded, initially supporting every device attached (with the exception that appropriate command-line parameters were specified). Regarding the use of this behaviour, I must admit that I need some extra time to figure it out... but I am sure that there can be some situation where you don't want the booting operating system to have access to all devices attached.

Enabling Disconnect/Reselect will make the corresponding device disconnect from the SCSI-bus during process of a command, then reconnect when ready. This makes the SCSI bus available for other actions or commands. A document scan for example would completely take up your SCSI bus until the task is accomplished - thus preventing you from doing anything else. Fortunately this option is enabled for all devices. Unfortunately, there are a lot of scanner models out there, that don't support the disconnect/reselect feature - letting you drop back to the "hourglass" effect.

It's a mess that this screen doesn't make use of the device names but rather their ID's only. Showing the names would require a scan for attached devices, which is not possible from within the setup screen. In boot sequence, this scan actually happens to take place after the BIOS setup .entry point.

I guess this was done to enable entering the setup immediately without having to wait for a completion of the scan process that could take up a lot of time in case that there's something wrong on the SCSI bus. I have to admit that I prefer Adaptec's solution: The BIOS setup starts with a menu screen allowing you to choose between the controller options and the device options. Latter option will automatically invoke the scan. That's not the real McCoy either but it's more comfortable to the user in my mind.

To conclude with the BIOS setup I can say that it's okay with me, even if it seems a bit poor compared to other manufacturer's solutions which sometimes even include low-level formatting or media verification (surface analysis) of attached hard drives.

At Dawicontrol they decided to put these functions into a DOS utility program contained on the (non-bootable) drivers disk. This program also handles flash upgrade of the adapter's BIOS by the way.

Okay now, one can argue whether such functionality has to be part of a BIOS setup or whether it's preferable to put them somewhere else, as they did at Dawicontrol. 

Driver install - take one

Personally, I like to distinguish between two ways of playing that game: First we have the install into a "running" system (if you're changing from previously installed different adapter for example) and second, an install within the OS installation process - that is to say, on a naked system.

In the first case (OS/2 is already installed) it would be possible to boot into a non-WPS OS/2 shell by pressing <AL T-F1>, then <F2> thanks to the adapter's support for INT13. There might be that message that the (previously installed) driver cannot be loaded and yes, you won't be able to operate your CD drives - but who cares? This would be sufficient to copy DC2976.ADD into the \OS2\BOOT directory, make the appropriate changes to CONFIG.SYS and everything would be okay... if you're lucky.

If you're not lucky, well, this would mean that the algorithms used for formatting by the controller manufacturer's aren't compatible. This can be noticed quite quickly - by a TRAP message. This will result in being forced to do a format. At installation time there can be a problem with OS/2 accessing the existing partition... frankly speaking: Prepare to have a hard night. If you don't like low-level formatting because of your hard disk's size you should at least consider to remove the target partition for install by using FDISK.

In general you can expect any Symbios-driven controller to be able to "understand" hard disk geometries created by an Adaptec controller. This is quite useful in case of not having a (current) backup of a specific hard disks or when dealing with removable hard disks being used in different systems. If you have the occasion to do a low-level format, you should give your controller the chance of doing so - the native access methods are always faster than any kind of emulation - regardless of how good they might be.

But let's stay with the facts - in my case everything went okay.
Anyway - this would be too simple, wouldn't it? Fine - here we go: 

Driver install - take two

Some weeks ago I already thought of doing a complete reinstall of OS/2 - so I found it to be a good occasion to go for it. Only requirement: A running system with a floppy disk drive.

I guess you know what's next: Adopting Disk 1 to make room for the driver(s)...okay. First, make a copy of Disk 1, delete CDINST.EXE and the README, then copy the driver onto it and edit CONFIG.SYS in the proper manner. (By the way: I prefer to remove all other "ADD's" belonging to controllers and all "FLT's" belonging to CD-ROMS by insertion of REM, making DC2976.ADD the only driver being loaded. Removing the snooper stuff can be done as well of course, but that's not the subject we're talking about right now).

Oh, yes: SET COPYFROMFLOPPY=1... whew, brother - don't forget that one! ;)
Now put in that Warp CD and the install disk and let's see what's happening... hmm... now that's cute... everything works. Oh come on - that's kinda boring... ;).

But anyway - it makes me notice, that more information is displayed at driver load time (with option /V) than at hardware boot. Along with the resource data (the same as at startup) it displays the driver's version, the power save mode selected (only configurable via the driver, default: disabled) and within the device list an additional column showing whether a device operates in sync or async mode.

The first glitch of the drivers is the absence of a presence checker for the controller (or chip at least). This can be noticed after the text-based part of the install process, when the install program's up: The selection list "support for SCSI-Adapters" shows "none". Well, to make this work, there's a lot more to do than the install process allows you to do. The SCSI.TBL must be edited and the presence checker program has to be included on the driver disk. Facing the efforts necessary for making a suitable "disk 1", they could have documented the (optional) steps required to enable automatic detection as well. But this would go too far - asking manufacturers to do some enhancements to IBM's tightened install process... anyway: I can't figure out, why there is a presence checker publicly available at the chipset manufacturer, but it has not found it's way onto the Dawicontrol disk.

After checking out if ZIP, CD and Streamer are functioning, there's really nothing to complain: The controller performs absolutely comparable to an Adaptec 2940UW and runs stable.

That's all I want. Now we'll take a look on FixPaks, as we're still running Warp 4 GA. Everything works as expected, except... 

FP14 (and kernel fixes)

This will lead us to the second "glitch" of the Dawi drivers: TRAP C at load time. This looks bad.

I take a look into the FAQs on Dawicontrol's web pages... nope. There's nothing about OS/2. I search for the e-mail-address of technical support... none. What - no mail, just phone?

This makes me prepare for the unpredictable and expecting the worst. But - hey - what's that? No service prefix of 0190 nor 0180-5 - just a 'usual' phone number. Phew.

(These prefixes in Germany indicate special service offerings which might cost you up to two Marks per minute or even more...)

So I pick up the phone, call them, and start to complain immediately. In details. The lady who patiently listened to all this stuff apologizes and tells me that she is "only" the operator and that I'll be passed to a support desk now. Oops. Quite quickly after that, there's a Sir asking what he can do for me. Having refined my speech, it takes me only a fraction of that amount of time to tell him the whole story. He feels sorry about their OS/2 specialist currently being out to lunch (that's right, it's about noon) but promises to take care of my problem. As an OS/2 user I secretly prepare to be abandoned for the next decades and that there'll be certainly no calls from Göttingen ever... saying "fine - see you." and hanging up.

Some hours later, there's the phone ringing. That from Dawicontrol is back. Incredible. He tells me that there are some problems with that new kernel from Aurora (WSeB), that's being implemented within FP14. (Well, anyone disagree out there...?). The developers who are only a few people can't take care of that for the moment, because they all had to team up for the release of a U160+-controller and it's drivers.

But as I checked it up in the meanwhile it's a Symbios chip they used on their board, so I ask him whether to use Symbios (LSI Logic) drivers and if that might solve the problem. He agrees, telling me that it's a good idea 'cause those Symbios drivers can be used in general, but he can't tell if the problem will be solved with that.

To sum up the whole story: Yep, it works. Symbios drivers for SYM53C875 makes FixPak 14 function perfectly.

Actually this would have been the end of my review, but as I am curious, I absolutely wanted to know if there were any differences between Dawicontrol's drivers and those from Symbios and what kind of differences that would be. 

"Test driven"

Up to the WseB-kernel both the Symbios drivers run on the DC-2976UW, as well as those from Dawicontrol. I decide to compare via Sysbench (V 0.9.3).

No matter what test I did, there are only minor differences between the competitors. Sometimes there appear to be minor advantages for Symbios drivers in matters of hard disk access, sometimes it's Dawicontrol's drivers who seem to have the advantage in matters of CD-ROM-access. From a general point of view those differences are so minor, that it's due to the way of benchmarking that they exist. This makes it even more interesting to take a close look at the functional differences, as for example: Symbios drivers, FixPak 12 and Device Driver Fixpak 2.

Strange thing. Everything went well up to this point, now the system already has trouble coming up: There's SCSI bus resetting and scanning for devices all the way, coming in sequence again and again. The boot process takes almost three minutes. Finally the WPS is up. I try to access the CD-ROM drive and there we are: Again: reset, scan, reset, scan... what the heck is he doing?

Having almost lost my patience, I'll try to watch for it after rebooting with <ALT-F2>. Trouble seems to start with loading of OS2CDROM.DMD. Hmm... maybe I should try to... Doing an audacious replace of OS2CDROM.DMD in CONFIG.SYS solves all problems immediately. The remedy's name: JJSCDROM.DMD - it's freeware by the way. I had the intention of doing that anyway, for it's necessary to enable digital audio extraction (DAE) on my Teac CD-532S.

Well, buddy - here I am back: Everything's fine now again. (In the meantime, I was told that OS2CDROM.DMD that comes with Device Driver Fixpak 2 appears to have problems with various CD-ROM-drives.) 

Result of the driver tests:

Up to the Aurora kernel, the drivers from Dawicontrol are preferable because of their flawless work regarding all versions of OS2CDROM.DMD. From Aurora (WSeB-) kernel onwards, there's no way out of the need for Symbios drivers (at least for the moment).

This might cause you troubles with OS2CDROM.DMD according to the FixPak level applied, but it's worth it anyway, for those problems can easily be circumvented by using JJSCDROM.DMD (freeware). It's mandatory for me anyway, as I can't do DAE out of the box with my Teac CD-532S under OS/2, as I already said above.

I have to admit that this test lacks a view on CD-writer and scanners, as I did not attach them to my PC. The scanner stuff is a subject to be discussed separately, as these kind of devices require special attention (especially when used with OS/2). Regarding CD-writers, I am sorry to only have checked CD-ROM-functions under OS/2. I discovered, that there are quite a few people out there having troubles using the Dawicontrol drivers - especially when dealing with CD writers and scanners. I can't tell if this is due (maybe in part) to the devices themselves or even the hosting PC itself. All I can say, is that these troubles seem to be circumvented by the use of Symbios drivers.

As a nice side-effect of their drivers, a presence checker for the SYM53C875 chipset is delivered with them - I already mentioned that subject, didn't I? By editing SCSI.TBL appropriately, specifying SYM8XXPC.EXE, the controller will be recognized and preselected automatically by the OS/2 install program.

In addition, the Symbios drivers provide extended device information when being loaded compared to their Dawi counterparts: It's the firmware version of each attached device. This turned out to be quite useful for me, as it gave me the chance to comfortably verify for firmware updates at Teac, enabling my CD-R56S writer to cope with that CD-Text feature. Okay, I might not absolutely depend on that one, as I don't have (nor know anyone who has) a CD player with CD-Text, but who cares? Ain't it nice to show off with that?...;)

Finally I would like to take the occasion to promise to do an additional review on "drivers in matter of scanning and CD-writing". My e-mail address is contained in this article's heading. So, if you can contribute to these subjects in matters of DC-2976UW (and OS/2 !), don't hesitate to give me your hints, trouble reports or any other kind of information. If you have any comments or questions regarding this review, you're welcome to do so as well. 


The Dawicontrol DC-2976UW offers good performance and quality at a very affordable price.
(Approx. 100 Euro / 97 US$ which equals to 1/3 of the cost of a comparable Adaptec model around here - I did not find information on pricing and distribution outside Germany, sorry.)

Anyway: In my opinion, this is a great product for home or SOHO use. Let me put it this way: Buy the Dawicontrol but use the Symbios drivers along with the freeware JJSCDROM.DMD. This will make you find yourself on the sunny side of SCSI.

Thomas Klein is IT consultant at Systor GmbH & Co. KG and is currently involved in software quality control in a large-scale project at IBM. He's been using OS/2 since version 2.11.

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