Switches on external 5.25" drive

[demolition]

I just cleaned up an awful looking Amiga 5.25" external floppy drive that I got a while ago. Everything is now painted black so it's looking like new now, except the labels on the back are missing. I did not note down what the switches did on the back as I figured I'd be able to figure it out afterwards, but it turns out it may not be so simple.

It has three switches and one of them is a write protect switch. The next is an enable switch and the third I figure is a 40/80 switch. I seem to remember the drive having that originally, however it is not working as I expect. If I flip the suspected 40/80 switch to one side, the drive does not even appear on the Amiga. Isn't it expected to show up and identify as a 40 track drive and format disks to 440kB? I tried flipping the switch from 80 to 40 while the system was on and formatted a disk and after track 40, it became noisier which indicated to me that it had reached the end of the disk, so double-stepping in 40 track mode.

I have never used a 40 track drive before, so how is it supposed to work?

[demolition]

I found out that my external drive is probably called Master 5A-1:
http://amiga.unikko.org/C-lehti/jpeg/1989/5/07.jpg

Does anyone else have this model and can tell me what's on the back?

[hooverphonique]

I am not completely sure, but I think the support for different capacities was introduced in kick 2.0. Which one are you using?

To let the amiga know it's 40 track, it sends a different 32 bit id pulse train through the RDY line..

[demolition]

After some tests I have verified one switch to be the 40/80 switch as I was able to dump a PC 360kB disk in 40 track mode but not in 80 track mode.

The problem is that if it is set to 40 tracks before I boot the machine, the drive never appears on the system, so the question is if this is some fault with my drive?

The drive has another problem - it does not work correctly with other drives connected after it. When I connect a 3.5" external drive after it, read access on the 2nd drive will also activate the 5.25" drive and the data will collide. So it seems it is not redirecting the MTR signals as it should. If I have the 3.5" drive first and the 5.25" drive last in the chain, I can use both drives without problems. There are some DIP switches on the back as well, so maybe this can be configured through those. There were never any info regarding these DIP switches even before I repainted the drive.

I am using a custom 3.9 kickstart and trackdisk.device is version 40.2. With a plain KS3.1, it gives the same result.

[Don_Adan]

Originally Posted by demolition

I just cleaned up an awful looking Amiga 5.25" external floppy drive that I got a while ago. Everything is now painted black so it's looking like new now, except the labels on the back are missing. I did not note down what the switches did on the back as I figured I'd be able to figure it out afterwards, but it turns out it may not be so simple.

It has three switches and one of them is a write protect switch. The next is an enable switch and the third I figure is a 40/80 switch. I seem to remember the drive having that originally, however it is not working as I expect. If I flip the suspected 40/80 switch to one side, the drive does not even appear on the Amiga. Isn't it expected to show up and identify as a 40 track drive and format disks to 440kB? I tried flipping the switch from 80 to 40 while the system was on and formatted a disk and after track 40, it became noisier which indicated to me that it had reached the end of the disk, so double-stepping in 40 track mode.

I have never used a 40 track drive before, so how is it supposed to work?

40 track option is for C64 or maybe old PC disks, not for Amiga disks.

[demolition]

I have seen mention of people using 440kB Amiga disks, so it might not be common but should still be supported.

[mark_k]

You can use 5.25" disks in 40-track mode, but you need to use a mount file. If I remember correctly, there is actually a 440KB mount entry on some Workbench disks (look in Devs/MountList).

After mounting the volume you should be able to format and use disks. Your drive might not support automatic disk change detection (Commodore's A1020 5.25" drive doesn't), in which case you need to do e.g. DiskChange PC2: after changing disks.

If you're mainly wanting to access PC-format disks, CrossDOS has a double-step setting/flag. By using that, you could leave the drive in 80-track mode (and be able to format 5.25" disks to 880KB), and CrossDOS would automatically double-step to access 360KB PC-format disks.

It sounds like your drive changes its ID when set to 40-track mode. That's actually a good thing, because it stops DOS & trackdisk.device trying to access it assuming the drive has 80 tracks.

[demolition]

So I managed to set up CrossDOS with double stepping in software by using DosType = 0x4D444400, so now I can leave the drive in 80 track mode and be able to read 360 kB disks.
For some reason, when the drive was set to 40 track mode (HW double step), I could make a disk image dump without problems, but accessing the file system through WB did not work properly. I could see the root directory but nothing else (block not found error). Now that double stepping is set up in CrossDOS instead of the drive, I can see and access all files without problems, although the end result should be the same..

I am now trying to set up two mount lists, one with double-stepping, the other one without, i.e. PC2/PD2 so I can access both 360kB and 720kB disks without editing and rebooting. Even though I use different dostypes, they always use the same setting, either they both double step or none of them do. Could there be an issue in using multiple instances of the same file system?

[mark_k]

Originally Posted by demolition

I am now trying to set up two mount lists, one with double-stepping, the other one without, i.e. PC2/PD2 so I can access both 360kB and 720kB disks without editing and rebooting. Even though I use different dostypes, they always use the same setting, either they both double step or none of them do. Could there be an issue in using multiple instances of the same file system?

I haven't tried doing that. Is there any particular reason you want to use 720KB PC format with 5.25" disks? Because a real PC probably wouldn't work with those (please correct me if that's wrong).

Maybe CrossDOS (mfm.device) maintains a single per-drive double-step flag, so it's not possible to use DOS drives with both single- and double-stepping??

[prowler]

Originally Posted by mark_k

Is there any particular reason you want to use 720KB PC format with 5.25" disks? Because a real PC probably wouldn't work with those (please correct me if that's wrong).

Yep, 5¼-inch DD disks will work up to at least 800K format in a DD drive fitted to a PC.

Originally Posted by mark_k

Maybe CrossDOS (mfm.device) maintains a single per-drive double-step flag, so it's not possible to use DOS drives with both single- and double-stepping??

I too think that this is the most likely explanation, and so two drive units will be required to avoid having to swap mountlists and reboot to change the number of tracks.

[mark_k]

Originally Posted by prowler

Yep, 5¼-inch DD disks will work up to at least 800K format in a DD drive fitted to a PC.

But would that require specific BIOS support? Because the original IBM PC and PC/XT had 40-track drives, and the PC/AT had an 80-track 1.2MB HD 5.25" drive (which could could read and with limitations write 360KB disks). But I don't think it supported 720KB on 5.25" disks out of the box.

Originally Posted by prowler

I too think that this is the most likely explanation, and so two drive units will be required to avoid having to swap mountlists and reboot to change the number of tracks.

Perhaps demolition could try using a alternative to mfm.device for the non-double-stepped case to work around that?

E.g. use CrossDOS/mfm.device for 40-track disks, and via another mount file use MultiDOS, MSH or XFS for 80-track disks. Maybe one of those could work with both 40- and 80-track disks so no need to use CrossDOS any more? [It may also be possible to use CrossDosFileSystem with multidos.device, messydisk.device or fd.device from those packages.]

[prowler]

Originally Posted by mark_k

But would that require specific BIOS support? Because the original IBM PC and PC/XT had 40-track drives, and the PC/AT had an 80-track 1.2MB HD 5.25" drive (which could could read and with limitations write 360KB disks). But I don't think it supported 720KB on 5.25" disks out of the box.

Yes, I think you're right that it actually requires a HD drive to read 80 tracks. Furthermore, it may have required a driver specifically for the 800K density. It was quite some time ago...

[demolition]

I had some 5,25" floppies that I wanted to back up and all of the DD ones I've been through so far seem to be 360kB, so maybe 720kB was very uncommon indeed? I just figured that if I was setting a system up for reading them, I'd like to cover both cases.

Anyway, it seems to work with both formats mounted simultaneously as long as they are not both using mfm.device. I set the non-double track drive to use multidos.device instead (but still with MultiDOSFileSystem) and then I can use one or the other. Problem now is that it will only display the correct label on the non-double track drive no matter what disk I put in, but I figure that is WB not liking two identical labels? Both drives can read the label since they can get that from track 0. Also, it is quite noticeable how much faster mfm.device is compared to using multidos.device. Feels like almost twice the speed when dumping an image.