5.25" floppy drive configuration

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Martin_Head
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Re: 5.25" floppy drive configuration

Postby Martin_Head » Fri Apr 17, 2020 12:43 pm

Cristian wrote:So, as confirmed also in the link here above, the DOS 720K format exists.
In any case... no way. I tried disks marked as "DS DD", "Double Side DD", "Single Side DD", Commodore64 and unidentified disks. Also 1.2MB disks. I tried all FLP_TRACK, FLP_DENSITY, FLP_JIGGLE combinations, both with SGoldcard and Trumpcard, Minerva and JM Roms.
I tried different flat cables and differnt PSUs, also the PC PSU. The format process starts normally, you can hear the usual rythmic floppy noises and at the end..... no way!
The same disks are still fully functional when the drive is connected to PC. For some super-odd reason, only one time I managed to read/write with QL a disk previously formatted with Quemulator.
There must be some special additional setting/hack to be done in the drive. Who knows!
Well, on the bright side, I got a fully working 5.25" floppy drive to be connected to my PC. Useful for recover/preserve data from old media (probably for any machine an emulator can manage, e.g. Commodore, Atari...)

It may be that the floppy disk controllers in the QL just cannot handle a 1.2M drive. I don't know if the specs for the chips would tell you.


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Pr0f
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Re: 5.25" floppy drive configuration

Postby Pr0f » Fri Apr 17, 2020 2:13 pm

The controller chips fitted to Gold or Super Gold card (8749) should be able to handle the DSQD format - but you would need DSQD or HC media (1.2MB) for that to work.

The Trump card flioppy controller (1771) will only go to DD format so 320K on a 5.25" and 720K on a 3.5"

From AT onwards the PC Floppy controller could handle 1.2Mb and 1.44MB respectively - but later models had the enhanced floppy controller that supported the ED floppy drives at 2.88MB and could also a tape unit, because of the formatting these controllers never got the 3.2Mb available with ED media on a QL. Although it was possible using these controllers to get as much as 1.68MB out of a standard HD floppy my messing with the track and sector counts - mileage varied..


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Dave
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Re: 5.25" floppy drive configuration

Postby Dave » Fri Apr 17, 2020 3:33 pm

What is the situation with termination resistors on the drives? If they're terminated incorrectly, they may accept "motor on" signals but not recognize data properly. On 5/25" drives, usually only the data lines were terminated on the last drive, with a resistor pack.


Derek_Stewart
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Re: 5.25" floppy drive configuration

Postby Derek_Stewart » Fri Apr 17, 2020 9:31 pm

Hi,

I had a 80 Track 5.25" Disk Drive on a QL with a Trump Card, which I have a copy of Turbo on 5.25"disk. All seemed to work okay.

I have old BBC Micro switchable 40/80 Track 5.25" disk drives, I will try them out over the weekend.


Regards,

Derek
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Cristian
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Re: 5.25" floppy drive configuration

Postby Cristian » Sat Apr 18, 2020 10:54 am

Dave wrote:What is the situation with termination resistors on the drives?

I wish I knew :( I know they are important, but I don't have experience with this matter. Could you help me to locate the resistors in the picture I posted please? As I told, the drive is normally recognized and managed when connected to PC: do you have additional tests to suggest?


Derek_Stewart
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Re: 5.25" floppy drive configuration

Postby Derek_Stewart » Sat Apr 18, 2020 11:14 am

Hi,

The Drive Select resistors, which are jimpers or wire links are labelled DS on the controller board. Which is where you have soldered some wires.

All PC floppy drives come pre-configured as Drive 1

Which on a QL relates to FLP2_

To change the hard wired drive select, twist IDC Floppy canle lines 10, 11, 12 for FLP1_ so that FLP1_ changes DS1 to DS0

FLP2 is a straight cable connecting DS1 to to FLP2_

Also note that a Trump Card can not access HD Disk formats, you need a Gold or Super Gold card.


Regards,

Derek
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Cristian
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Re: 5.25" floppy drive configuration

Postby Cristian » Sat Apr 18, 2020 1:07 pm

Derek_Stewart wrote:The Drive Select resistors, which are jimpers or wire links are labelled DS


Oh, but then the "termination resistors" are nothing but what I knew as the "drive select contacts/jumpers". Thank you for the clarification.
Yes, from the beginning I set the drive to DS1 and used a non-twisted flat cable. The drive is recognised as FLP2_.


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dex
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Re: 5.25" floppy drive configuration

Postby dex » Sat Apr 18, 2020 1:38 pm

Cristian wrote:
Derek_Stewart wrote:Oh, but then the "termination resistors" are nothing but what I knew as the "drive select contacts/jumpers".

Wrong!
You mixed the two answers together.

o4zh00C.jpg


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Cristian
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Re: 5.25" floppy drive configuration

Postby Cristian » Sat Apr 18, 2020 2:35 pm

Oh, sorry. I misunderstood Derek's reply. Thank you for your clarification.
Still, I don't know what should I do with these termination resistors...


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dex
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Re: 5.25" floppy drive configuration

Postby dex » Sat Apr 18, 2020 2:53 pm

Cristian wrote:Still, I don't know what should I do with these termination resistors...

Same as on SCSI.
Remove on the thru device, keep them in place on the last device.
(Excepting 3,5" drive).

http://www.minuszerodegrees.net/diskette/5.25_floppy_drive_termination.jpg
or
https://retrocmp.de/fdd/general/resistor-3.png



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