CompuServe Drives: Custom firmware?

Cory Smelosky b4 at
Sat Apr 18 11:21:43 CDT 2015

Sent from my iPhone

> On Apr 18, 2015, at 03:48, Tothwolf <tothwolf at> wrote:
> On Sat, 18 Apr 2015, Cory Smelosky wrote:
>>> On Apr 18, 2015, at 02:55, Eric Smith <spacewar at> wrote:
>>> My memory is probably faulty about exactly what the WD suffix means. I still think it's 16-bit "ultra" (1), but Wikipedia says that ultra (1) is single-ended or HVD, ultra 2 is LVD or HVD, and ultra 3, 320, and 640 are LVD only.
>> The manual did confirm WD is definitely HVD which explains my issues.
>> I recall some sort of Ultra bit in it as well.
> I was writing this when you sent the above reply ;)
>> ST34573WD
>> ST32550ND
> W -- wide
> N -- narrow
> WD -- wide differential
> ND -- narrow differential
> You'll need a converter. These type of differential drives can't be connected directly to a single ended bus, wide or narrow. If you do, you are connecting one side of the differential pair to ground, and these drives don't like that. There are also signal differences, see the pinouts for wide and wide differential and look at the pin numbers for attention, busy, ack, reset, etc. Later LVD devices could detect which sort of bus they were connected to, but these drives can't.

Or I can order an HVD card as all of my cards are bad anyway.

Happen to have recommendations for an converter? I don't have a massive surplus of HVD drives so I'll need 1 of those as well.

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