(PC to Amiga) Floppy Drive change from DS1 to DS0

[Sim085]

I cannot understand some of the changes out there in relation to the switch from DS1 to DS0.

To change a PC floppy drive to an Amiga floppy drive one needs to do three things;

1. Change drive from unit 1 to unit 0.
2. Route Disk-Change to pin 2.
3. Route RDY signal to pin 34.

From what I can find out there step 2 only requires to cut trace to pin 34 and route this to pin 2 instead and for step 3 connect pin 34 to pin 30.

What I cannot understand is how to set the drive unit to 0 instead of 1;

From what I read the Amiga floppy drive header has Pin 10 to report the Drive as Unit 0 and Pin 12 to report the Drive as Unit 1 and Pin 16 to turn Motor on/off (link).

On the other hand a PC floppy drive has Pin 12 to report the Drive as Unit 1 and Pin 14 to report the Drive as Unit 0 and Pin 10 to turn Motor Drive 0 On/Off (link).

So am I correct that on a PC floppy drive I can simply (always, regardless of floppy drive model).

- Cut traces going to Pin 10, Pin 12, Pin 14 and Pin 16.
- Route trace previously linked to Pin 14 to Pin 10.
- Route Pin 16 to trace previously linked to Pin 10.

Is the above correct or am I missing something?

Also, am I correct that a drive which does not report itself as Drive 0 will result in the Amiga reacting as if no drive is attached?

[hooverphonique]

https://old.pinouts.ru/HD/InternalDisk_pinout.shtml
Amigas use the Shugart pinout. PC's use a twist in the cable for pin 10-16 which selects drive A or B (A after the twist).

If you can't use a jumper to set DS0, you can use the cut trace/wire method, yes.

The Drive 0/1/2 signals are not drives "identifying" themselves towards the computer, but for the computer to select which drive it communicates with.

[Sim085]

Thank you hooverphonique. That link is very helpful

The particular drive I am attempting this on does no have a jumper for DS1 to DS0 so have no other option then to do the cut tracing.

Originally Posted by hooverphonique

https://old.pinouts.ru/HD/InternalDisk_pinout.shtml
Amigas use the Shugart pinout. PC's use a twist in the cable for pin 10-16 which selects drive A or B (A after the twist).

If you can't use a jumper to set DS0, you can use the cut trace/wire method, yes.

The Drive 0/1/2 signals are not drives "identifying" themselves towards the computer, but for the computer to select which drive it communicates with.

[Sim085]

So the first moment I got I have tried to convert a PC floppy drive I had to Amiga.

Given in Shugart pinout pin 16 is Motor On and in PC pinout this is Motor Enable B I reasoned; as long as the correct pair is enabled (Drive Sel B and Motor Enable B) it would not make a difference if Amiga Device Select 0 results in Drive Sel A or B and therefore I cut traces to pins 10 and 12 and then re-routed pin 10 (/DS0) to trace for pin 12 (/DRVSB).

Is this correct?

I then also did the changes for the DCD and RDY and tested the drive.

The drive clicks when I turn the amiga on (A500) but does not recognize any disk. I have tryed SysTest. The first thing I can notice is that SysTest reports "no track 0". I cannot understand this because in both Shugart pinout and PC pinout the TRK00 is pin 26 on which I did not do any alteration. I also double checked with multimeter and can confirm that this pin is connected.

Would anyone know what I might have done wrong?

[stevsurv]

Have a look at this vid, it may help -

[ Show youtube player ]

[Sim085]

Thank you for the video.

I have one exactly like that one. It is a pretty easy conversion because of the jumper ready available on the board to change from DS1 to DS0.

This other drive I have does not have such a jumper and that is why I had to go directly through trace cutting for the DS1 to DS0 change. It must be something with this area as the change and ready signal I did them exactly like for the other drive and systest reports both a ready signal and a disk change.

Originally Posted by stevsurv

Have a look at this vid, it may help -

[ Show youtube player ]

[hooverphonique]

Move the heads to track 0 (outer) and use the multimeter to measure voltage on the track 0 signal, then power the amiga on. If you for every step (at the boot screen) get alternating 0V/5V, then the drive probably reports track 0 correctly, and the problem is elsewhere.

[solarmon]

@Sim085,

What is the make/model of the drive you are trying to mod? Please provide a picture of it and the mod you have done.

When you say SysTest (now known as Amiga Test Kit) is reporting "no track 0" - where exactly does it report that - during which test?

[Sim085]

The drive is JU-256A347PC K2. Attached is a photo of the drive header with no-hacks and same drive header with the hacks I have applied.

With regards to the DS1 to DS0;

I have cut traces from pin 10 (purple) and pin 12 (orange) and then linked pin 10 to trace which previously took to pin 12.

When I reason about it I see it as follows:

/DS0 [10] > [12] /DRVSB
/DS1 [12] > [-] (connected to nothing)
/DS2 [14] > [14] /DRVSA (unchanged)
/MTRON [16] > [16] /MOTEB (unchanged)


Amiga Kit states "no track 0" from the Floppy Drive screen (F3), Signal Test screen (F5).

Originally Posted by solarmon

@Sim085,

What is the make/model of the drive you are trying to mod? Please provide a picture of it and the mod you have done.

When you say SysTest (now known as Amiga Test Kit) is reporting "no track 0" - where exactly does it report that - during which test?

[solarmon]

Can you provide a picture of when ATK shows 'no track 0'. I haven't come across that on that Signal Test screen. Are you testing the drive as DF0 or DF1?

In you picture of the mod, I see you have connected pin 30 (/RDATA) to pin 34. This doesn't look right - there is meant to be a READY signal going to pin 34.

[Jope]

You can see near your cut that there was a hard wired DS0/1 jumper there.

The hardwired jumper is the trace between the two pads to the right of the orange cut. You could have severed that and then bridged the middle and lower pad.

Your modification did the same thing of course, but just something to consider for future drives. If you modify it to stay true to the original intention of the PCB layout artist, you can easily switch between 0 and 1 later if you want to move the drive to a big box machine as DF1 for example.

[solarmon]

Yes - it looks like R41 and R42 are the DS0/DS1 jumpers, and it is hardwired for R42 (DS1) by default.

[Sim085]

I looked and looked for something labelled DS0 DS1 (like the other drive) and to be honest I did find it strange that those two pads where connected!

Originally Posted by Jope

You can see near your cut that there was a hard wired DS0/1 jumper there.

The hardwired jumper is the trace between the two pads to the right of the orange cut. You could have severed that and then bridged the middle and lower pad.

Originally Posted by solarmon

Yes - it looks like R41 and R42 are the DS0/DS1 jumpers, and it is hardwired for R42 (DS1) by default.

Will do.

Originally Posted by solarmon

Can you provide a picture of when ATK shows 'no track 0'. I haven't come across that on that Signal Test screen. Are you testing the drive as DF0 or DF1?

Connecting pin 34 to pin 30 is something I saw for a similar drive on the forum. Again I did this as I did not find any pad marked as RD or RDY.

Originally Posted by solarmon

In you picture of the mod, I see you have connected pin 30 (/RDATA) to pin 34. This doesn't look right - there is meant to be a READY signal going to pin 34.

[Sim085]

So I have "reverted" the changes I did with regards to DS0/DS1. Cut the trace between R41 and the pad between this and R42 and instead did a blob between this pad and R42. Connected everything and the results are the same.

Below are screenshots from Amiga Test Kit. Note that Track 0 is found if I manually move the head backwards.

[solarmon]

How did you launch ATK? Did you boot from DF0, or run from hard drive? What is your Amiga model?

Looking at the jumper/pads again, the middle one has traces going above (to a via/test-point?) and below it (I assume not going to a pin, but to the IC1 chip). Can you confirm that the R41 pad on the right goes to pin 10.

[solarmon]

The "DF0: No Track 0 (Drive not Present?)" message means that it cannot select the drive because the drive is not responding on DS0.

I have simulated/tested this by changing a floppy drive, that was working on DF0, from DS0 to DS1 (or by removing the jumper completely) and I get that message.

[Sim085]

Started ATK from Hard Disk.


Yes, used multi meter to confirm R41 goes to pin 10 and R42 goes to pin 12. Does this make sense



The pad between R41 and R42 goes to pin 16 of the IC1 Chip.

Originally Posted by solarmon

How did you launch ATK? Did you boot from DF0, or run from hard drive? What is your Amiga model?


Looking at the jumper/pads again, the middle one has traces going above (to a via/test-point?) and below it (I assume not going to a pin, but to the IC1 chip). Can you confirm that the R41 pad on the right goes to pin 10.

[Sim085]

Just want to add some more information.



When I manually move the head backwards or from Signal screen I press F2 (select DF1 and then F1 (select DF0 the Track 0 is identified (see screenshots below). However it is soon lost the moment I try to do another signal test.

Originally Posted by solarmon

The "DF0: No Track 0 (Drive not Present?)" message means that it cannot select the drive because the drive is not responding on DS0.

I have simulated/tested this by changing a floppy drive, that was working on DF0, from DS0 to DS1 (or by removing the jumper completely) and I get that message.

[solarmon]

Is this a known working PC floppy drive? I.e. was it working as a PC floppy drive?

Do you see pin 10 go low (ground or 0V)?

The ready and disk change signals are a separate thing to get working. We need to get it to respond to DS0 first!

[solarmon]

It could be that the mod changes are shorting somewhere - check that there is no shorts between R41 and R42 pads, or between Pin 10 and pin 12.