Microdrive Unit Design

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RWAP
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Microdrive Unit Design

Postby RWAP » Mon Jan 26, 2015 10:15 pm

I had a bit of a sort through my microdrive units yesterday and have just been getting another QL up and running.

I decided to use some of the non-keyed microdrive units (ie. they have straight edges, not the jigsaw pieces which seem to appear on most units).

Having gone through several drives to get two working units, I was pleasantly surprised.

FORMAT mdv1_

produces up to 231/233 sectors

Compare that to the other microdrive units, which tend to return 218/222 sectors as a maximum.

mdv2_ gives slightly lower results, but it does appear that there is a difference between the keyed and non-keyed units.

I wonder which were the earlier ones?


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Re: Microdrive Unit Design

Postby Mr_Navigator » Tue Jan 27, 2015 9:51 am

Pics?


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RWAP
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Re: Microdrive Unit Design

Postby RWAP » Tue Jan 27, 2015 2:48 pm

First the more common (at least in Europe) microdrive unit with the two keys on the edge:
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Re: Microdrive Unit Design

Postby RWAP » Tue Jan 27, 2015 2:49 pm

Now the less common microdrive unit with straight edges - note the extra red wire on the PCB - I have seen the one in a plastic sleeve on some of the units with 2 keys...
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Last edited by RWAP on Tue Jan 27, 2015 2:51 pm, edited 1 time in total.


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Re: Microdrive Unit Design

Postby RWAP » Tue Jan 27, 2015 2:51 pm

Finally the very rare unit with just one keying piece - I actually have two of these, so will have to try them in a QL some time... (the keying piece is bigger than the one with 2 keys)
Attachments
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Re: Microdrive Unit Design

Postby Tom Phobos » Tue Jan 27, 2015 4:14 pm

Nice :) I'll check out what type of drives are built into my german QL. Actually i only formatted one cart in the drive. It was empty, the first formatting attempts returned "format error". After a successful format it now has 202 sectors.


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Re: Microdrive Unit Design

Postby Ralf R. » Tue Jan 27, 2015 4:25 pm

RWAP wrote:Having gone through several drives to get two working units, I was pleasantly surprised.

FORMAT mdv1_

produces up to 231/233 sectors

Compare that to the other microdrive units, which tend to return 218/222 sectors as a maximum.


When I once built my (long non-existent) "QL-T", a non-PC desktop case with one mdv, I came across, that putting an diode in the drive_select lets you use one mdv for both 1 and 2.

And....making the motor a bit faster (I think there was a potentiometer on the PCB) gives more sectors. So I think, one of your mdv is running a bit faster than the other. I was able to get 235 sectors, but had not used this speed.


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Re: Microdrive Unit Design

Postby chriskgnr » Tue Jan 27, 2015 6:18 pm

where on the pcb is that potentiometer?


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Re: Microdrive Unit Design

Postby RWAP » Tue Jan 27, 2015 7:38 pm

Ralf R. wrote:
And....making the motor a bit faster (I think there was a potentiometer on the PCB) gives more sectors. So I think, one of your mdv is running a bit faster than the other. I was able to get 235 sectors, but had not used this speed.


Yes I guess that for some reason, the microdrive units with straight edges run at a different speed - although they can still read/write cartridges formatted on the ones with the keyed edges.

I have tried two microdrive units with the straight edges and both give this higher number of sectors.

I have a feeling that these were used in the early QLs but then maybe for reliability, they slowed down the motor and used the keyed system to identify the newer version?


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Re: Microdrive Unit Design

Postby Cristian » Fri Oct 06, 2017 1:44 pm

Ralf R. wrote:
And....making the motor a bit faster (I think there was a potentiometer on the PCB) gives more sectors.

This looks illogical for me. If the tape is faster the sectors should be larger, am I wrong?



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