CompuServe Drives: Custom firmware?

Rich Alderson RichA at
Mon Apr 20 13:29:37 CDT 2015

From: Cory Smelosky
Sent: Saturday, April 18, 2015 9:22 AM

>> On Apr 18, 2015, at 03:48, Tothwolf <tothwolf at> wrote:
>> 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.

There is an Adaptec card and 2 LSI Logic (Symbios) cards, all under $100, all
marked "used pull".

> 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.

I like the Paralan products (we used them in the XKL Toad-1 to connect a DAT
drive--later a DLT--to the HVD bus), but they run $300-$500 each new.  I don't
know whether there is a used market.


Rich Alderson
Vintage Computing Sr. Systems Engineer
Living Computer Museum
2245 1st Avenue S
Seattle, WA 98134

mailto:RichA at

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