Python list vs google group

[Jim Lee]

On 06/15/2018 07:08 PM, Richard Damon wrote:
> On 6/15/18 9:00 PM, Jim Lee wrote:
>>
>> On 06/15/2018 05:00 PM, Chris Angelico wrote:
>>> On Sat, Jun 16, 2018 at 4:52 AM, Rob Gaddi
>>> <rgaddi at highlandtechnology.invalid> wrote:
>>>> On 06/15/2018 11:44 AM, Larry Martell wrote:
>>>>> My favorite acronym of all time is TWAIN
>>>>>
>>>> Really?  I always thought it didn't scan.
>>>>
>>> Having spent way WAY too many hours trying to turn documents into
>>> images (and text), I very much appreciate that laugh.
>>>
>>> ChrisA
>> I once had a Mustek color scanner that came with a TWAIN driver.  If
>> the room temperature was above 80 degrees F, it would scan in color -
>> otherwise, only black & white.  I was *sure* it was a hardware
>> problem, but then someone released a native Linux driver for the
>> scanner.  When I moved the scanner to my Linux box, it worked fine
>> regardless of temperature.
>>
>> -Jim
> There actually may still have been a hardware issue, likely something
> marginal in the timing on the cable. (Timing changing with temperature).
> It would take a detailed look, and a fine reading of specs, to see if
> the Windows Driver was to spec, and the hardware is marginal (but the
> Linux driver didn't push the unit to full speed and got around the
> issue), of if the Windows driver broke some specification but still sort
> of worked, especially if things were warm, while the Linux driver did it
> right.
>
You are exactly right.  It was so long ago that I forgot some of the 
details, but it boiled down to the TWAIN driver pushing the SCSI bus out 
of spec.   I remember looking at the bus on a scope, measuring pulse 
widths, and playing with terminator values to try to optimize rise 
times.  I don't believe it used the Windows SCSI driver at all, but 
instead drove the scanner directly (I could be remembering wrong).

-Jim