[Coco] CoCo Model 1 Cartridge Port

[Rick Ulland]

The 'head banger bug' has been a CoCo tradition for decades. Maybe the 
cheap 35trk ss drives?
A new old mystery.


On 12/30/21 11:03 AM, Alex Evans wrote:
> The coco recognizes the track 0 sensor line. It should not be banging the
> head. It should step to track 0 and know then that it is on track 0.
>
>
> On Fri, Dec 24, 2021 at 11:02 AM Rick Ulland <rickulland1 at gmail.com> wrote:
>
>> On 12/24/21 8:48 AM, Charles Hudson wrote:
>>> Following your advice I moved the cable to the last connector (on the
>>> end with two connectors) and repeated the process of "dksini0".  This
>>> time the drive light came on and I could hear the stepper motor move
>>> the head.  I failed to count the steps - I was completely surprised -
>>> but a dozen steps or more activity ceased and the light went out.  The
>>> result on the screen once again stated IO ERROR.
>>>
>>> I then tried repeating the disk format.  This time I heard the
>>> mechanism straining; no regular repeated stepping and after a few
>>> steps with long pauses between them the activity ceased and I got
>>> another IO ERROR message.
>>>
>> I'd bet dollars to donuts Art is correct. The way a CoCo drive is
>> supposed to work, you turn it own. The head position is unknown. First
>> operation steps the head a whole buncha times, to make sure it's banged
>> against the end stop for a while. DECB still doesn't know the head
>> position, but assumes surely this is 0 and counts from here until death.
>> If the head doesn't move, or doesn't move properly, DECB doesn't know
>> and forges ahead until there is a read error.
>>
>> Pop the top, watch the show. Bring hair clipper oil for the dry slide
>> rails. And Merry Christmas.
>>
>> -ricku
>>
>>
>>
>>
>>
>>
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