The Sinclair QL Forum

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?

Pics?

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

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...

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)

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.

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.

where on the pcb is that potentiometer?

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?

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?