2940 Taxonomy; was: Re: SCSI cable needed

[Jeff Walther]

>Date: Tue, 26 Sep 2006 19:19:55 -0400
>From: "Roy J. Tellason" <rtellason at verizon.net>

>On Tuesday 26 September 2006 07:03 pm, Sridhar Ayengar wrote:
>>  Roy J. Tellason wrote:
>>  >> I do have the book for the burner handy,  and the cable shown in there
>>  >> is round. And the connector on the burner (2 of them actually) is
>>  >> *smaller* than the external connector on the 2940,
>>
>>  If I'm right that you're running a 2940W (or 2940UW or 2940U2W) instead
>>  of a 2940, the cable you're looking for is HONDA68 -> HONDA50 *with
>>  high-byte termination*.
>
>I understand the need for the high-byte termination you mention here,  as that
>may be at the root of some of the problems that I've seen others mention in
>this thread.  What I don't understand is why a card that has only a 50-pin
>internal connector would have a 68-pin connector on the external bracket.
>
>It also came as a bit of a surprise to me that when I pulled out my box of
>those cards I found that even though all three of them had the same model
>number that they were apparently three different cards...

Adaptec used the same circuit board for several different products. 
In every case the circuit board has the same markings, but by 
populating the board in different ways they made different products.

I'm going from memory here, so if I get some details wrong feel free 
to nitpick me.

The 2940UW has an external HD68 pin connector with screw fasteners 
and internally it has an IDC50 ribbon cable connector and a 68 pin 
ribbon cable connector.

The 2940U has an external HD50 connector (with clips) and an IDC50 
ribbon cable connector internally.

The Macintosh version of the 2940UW is just like the PC version, 
except it has a 1Mb (as opposed to 512Kb) Flash chip programmed with 
different firmware.

There was also a Sun version of the card with Open Firmware code on 
board.   You used to be able to download the firmware updater back in 
the good old days when Adaptec had a very comprehensive ftp site 
accessible to the public (why did so many companies shut down their 
public ftp sites?).

I think there was also a differential (HVD) version of that card on 
that board, but I may be misremembering.

The 2940 (no U) is a slightly different card because there's only a 
position on board for a DIP packaged Flash (or EPROM) chip and no 
PLCC nor (I think) SOIC position.

To further complicate matters there were at least two later variants 
of the 2940UW, the 2940UW Dual and the 2940UW Pro.   AFAICT, these 
two later variants used a different controller chip than the 
X940U[W].  The X940U[W] uses an AIC-7880.  I think the two later 
variants use a 7895, but that's a low reliability memory on that last 
part number.

While the 2940UW uses a 68 pin external connector with screw 
fasteners, there are versions of the 68 pin external connector with 
clips.    It is found on the FWB (Stream Logic) NuBus JackHammer SCSI 
card, for example.   And 68 pin external terminators exist in both 
variants to correspond with both types of connectors found in the 
wild.

Jeff Walther