Dual FDD problems

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Whopper
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Dual FDD problems

Postby Whopper » Fri May 04, 2018 6:00 pm

I have a BBQL, with Tetroids Gold Card Clone, Tetroids SMPS, and the 68008 cpu removed. I can run a dual DD (720KB) FDD set with no problems. But, when I try to run a dual HD (1.4MB) FDD set I have problems.

1) FLP1 cannot be formatted. It gives a "Read Only" error
2) FLP2 can be formatted and shows 2880/2880 sectors.
3) Nothing can be written or read from FLP1 or FLP2, it gives a "Not Found" error.
4) I have rotated three FDDs through each position, and used two different (new) FDD cables. Each with lines 10 to 16 twisted between FLP2 and FLP1
5) I have tried different FLP_START and FLP_STEP values without success.
6) I have tried my Trump card without success but I believe it to uses the 1772 chip so that wouldn't work anyway.
7) I have continuity tested both cables and all lines are correct.
8) Removing FLP1 does not allow FLP2 to work correctly.

I am currently out of ideas. Please, can anyone help?


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Cristian
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Re: Dual FDD problems

Postby Cristian » Fri May 04, 2018 7:35 pm

Whopper wrote:and used two different (new) FDD cables. Each with lines 10 to 16 twisted between FLP2 and FLP1


I can confirm that TrumpCard needs non-twisted flat cables for dual FDD.
Can anyone confirm if GoldCard needs twisted cables or not?


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tofro
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Re: Dual FDD problems

Postby tofro » Fri May 04, 2018 8:25 pm

No normal computer needs twisted floppy Cables. There’s only one exotic type of computer named „IBM compatible„ that ever used such cables.

Jokes aside, none of the QL disk interfaces ever used twisted cables.

Tobias


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Re: Dual FDD problems

Postby RWAP » Fri May 04, 2018 8:55 pm

tofro wrote:No normal computer needs twisted floppy Cables. There’s only one exotic type of computer named „IBM compatible„ that ever used such cables.

Jokes aside, none of the QL disk interfaces ever used twisted cables.

Tobias


True, but the QL disk interfaces also expected the drives to be jumpered to set one as DS0 (flp1_) - standard PC drives are set to be DS1 by default. Most PC drives no longer have jumpers (or a solder pad which can be used to set them to DS0).

It sounds as though this is the problem here - both drives are identifying themselves as DS1 so attempts to access flp1_ fail (there is no DS0).
Attempts to accesss flp2_ actually access the first drive (due to the straight cable). However, the twist in the cable between both drives probably means that the second drive is also being accessed - hence the failure to read any data.

There is a way of getting around this by twisting wires 10 and 12 (I think from memory) between the QL and the first drive (so it identifies it as DS0) and then re-twisting them between drive 1 and drive 2 (so drive 2 is still identified as DS1)


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Whopper
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Re: Dual FDD problems

Postby Whopper » Fri May 04, 2018 9:09 pm

Rich,

Just changing lines 10 & 12 will swap Motor Enable A and Drive Select B around.

Twisting lines 10 to 16 swaps the motor enables and the drive selects over.


Also just having FLP2 fitted still didn't produce any reads / writes.

The thing that really annoys me is that the dual 720K DD FDDs I have work perfectly. I'm just greedy enough to want a dual 1.4MB setup too.

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Cristian
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Re: Dual FDD problems

Postby Cristian » Fri May 04, 2018 9:35 pm

Which kind of dual HD drives set are you using? Is it a vintage device (designed for old machines like Spectrum, QL etc)? Or are you using a "new" one, containing "modern" floppy drives (the same used for PC)?


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Re: Dual FDD problems

Postby RWAP » Fri May 04, 2018 10:38 pm

Whopper wrote:Rich,

Just changing lines 10 & 12 will swap Motor Enable A and Drive Select B around.

Twisting lines 10 to 16 swaps the motor enables and the drive selects over.



And it works if you want to connect two standard issue PC floppy disk drives to a QL interface... Not sure why!

Whopper wrote:Also just having FLP2 fitted still didn't produce any reads / writes.


But you have several lines swapped over which might well affect how the QL recognises the drive. Connect one drive to the connector before the twist, and I bet you can do DIR flp2_, FORMAT flp2_, read and write.

Attaching it after the twist will just not work.

The thing that really annoys me is that the dual 720K DD FDDs I have work perfectly. I'm just greedy enough to want a dual 1.4MB setup too.


That is probably because the DD disk drives are early and designed to work with an untwisted cable (ie have jumpers or solder pads which have been used to set the one drive to DS0).


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Re: Dual FDD problems

Postby afx » Sat May 05, 2018 9:31 am

I had some similar problems with my classic GoldCard and HDD (1.4MB) PC drives.

In my system, with these commands in the boot, everything works correctly:

FLP_JIGGLE 1
FLP_DENSITY 'H'


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Whopper
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Re: Dual FDD problems

Postby Whopper » Wed May 09, 2018 6:20 pm

afx wrote:I had some similar problems with my classic GoldCard and HDD (1.4MB) PC drives.

In my system, with these commands in the boot, everything works correctly:

FLP_JIGGLE 1
FLP_DENSITY 'H'



Yes, well... ummm, flp_jiggle???

But these commands worked! Thank you afx, I'm making progress on my setup now.


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Whopper
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Re: Dual FDD problems

Postby Whopper » Sun May 13, 2018 4:07 pm

Notes on QL floppy drives.

Well, over the past few weeks I've been looking at why my Tetroid clone Gold Card won't use two 1.44MB floppy drives, while it's perfectly happy with two (older) 720KB drives. A number of people helped me with this investigation. Now here is what I discovered.

The main QL drive devices use a SHUGART interface. This interface was quite common for the earlier devices, but fell out of favour when the IBM PC was introduced with it's own interface. The pinouts for both interfaces can be found on many internet sites. (URL - 1)

Using the Shugart interface up to three devices can be addressed, DS0 (Device Select 0), DS1 (Drive Select B) and DS2 (Device Select 2). Why the name change, no idea.

FLP_JIGGLE : This is defined in the Miracle Systems Super Gold Card manual. It allows the user to set / reset the head movement control on each floppy drive, individually or collectively.

FLP_DENSITY : This is defined in the GOLDuser.doc (URL - 2) using the command FLP_DENSITY 'H' sets the floppy driver to use the high density diskettes.



I am now waiting on the delivery of 34 pin IDC cable and 34 pin sockets from China to build a couple of my own Shugart cables. and investigate the possibility of accessing three floppy drives.


URLs
1) Pin outs of IBM PC 34 pin floppy controller and Shugart 34 pin floppy controller.http://pinouts.ru/HD/InternalDisk_pinout.shtml

2) GOLDuser.doc https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ved=0ahUKEwid9LDkgfzaAhUUbMAKHcQCD7UQFghKMAQ&url=http%3A%2F%2Fwww.dilwyn.me.uk%2Fdocs%2Fsmsqegd2%2Fsmsqe%2FGOLDuser.doc&usg=AOvVaw26MhmqtZ6KQ_M4Jf3SOBCX


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