A1200 using external Gotek as DF0

[Vyncynt]

Hello everyone,
I have an Amiga 1200 and use my Gotek drive internally. I am hoping to transfer the Gotek to an external floppy drive enclosure (California Access CA-880) via the external floppy port, but still retain DF0: functionality. If at all possible, I would prefer to avoid cutting into the case or having a ribbon cable sticking out.

Any recommendations or advice how to do this?

[bolding]

I believe you need something similar to: https://amigastore.eu/en/485-df0-selector.html

[demolition]

I think you need to do a small modification on the motherboard just like on an A600 since you can't just pull the CIA chip out of its socket like you can on a 500. Here's one doing the mod on a 600:
[ Show youtube player ]

[bolding]

Originally Posted by demolition

I think you need to do a small modification on the motherboard just like on an A600 since you can't just pull the CIA chip out of its socket like you can on a 500. Here's one doing the mod on a 600:
[ Show youtube player ]

Think you need to listen to demolition - I'm also learning here

[Daedalus]

Yep, the only way to do it other than running the ribbon out is to modify the board since you need to swap a hard-wired signal. That's me in the video doing the mod (drunk, so probably not the most wonderful example but it worked). At least this method is easy to reverse by replacing the resistor and the floppy cable - some people have done it by cutting traces...

[aeberbach]

I thought about this when doing the internal power supply thing. The internal floppy is gone so you need an external floppy to be DF0: Unfortunately the drive select line is hard wired to the internal floppy header and is not easy to get at like in the a A500 or A2000. The best way seems to be to attach a connection to the internal header to get at the drive 0 select signal, and to then completely remove the external floppy socket and wire to that. Probably not too hard if you have a vacuum desoldering tool.


Without being sure I think if you cascaded the lines - connected drive 0 to drive 1, connected drive 1 to drive 2, connected drive 2 to drive 3 - then you could connect as daisy chain drives 0, 1, 2 through the external connector.


You will need to take a look at the A1200 schematics to see what I mean I think. https://www.amigawiki.org/dnl/schematics/A1200_R1.pdf page 9: you would connect nothing to the internal header except pin 10, which would be connected to pin 21 of the external floppy connector (which of course would be desoldered and connected to nothing else). To get DF1: functional as a daisy chain, lift pin 9 of the external floppy connector and connect that to pin 12 of the internal header. All other connections to the external floppy connector as normal.

[Daedalus]

Removing the external floppy socket is a bit overkill when it can be done with a couple of jumper wires and the removal of one resistor. The only significant difference with the external socket is the /MOTOR signal, and that isn't needed for a Gotek.

[solarmon]

Alternatively, keep both Gotek and original floppy disk drive internally:

https://www.ikod.se/amiga-1200-gotek/

[demolition]

Originally Posted by solarmon

Alternatively, keep both Gotek and original floppy disk drive internally:
https://www.ikod.se/amiga-1200-gotek/

After watching in horror so many people butcher their Amigas it is nice to see when someone takes the time to do something properly.

[aeberbach]

The point of removing the drive connector is to modify only the replaceable socket - if the signals are accessible without doing so that would be better, I only looked quickly at the PCB for this. I have never made holes or used glue or done anything that can't be undone when modifying an Amiga...

[demolition]

It is not exactly easy to remove the external drive connector. The ground plane fights really hard against removal so you need skills and the right equipment to remove it without damaging the motherboard. If you wanted to avoid modifying the MB, it would be a lot easier to simply cut the DS pin on the back side of the connector, solder two wires to the exposed ends and inject the switching electronics needed there.

[bolding]

Originally Posted by demolition

After watching in horror so many people butcher their Amigas it is nice to see when someone takes the time to do something properly.

I agree - it's a cool mod and done properly. However, I'd never do that to any of my machines I'd go the non-destructive route.

[solarmon]

Originally Posted by bolding

I agree - it's a cool mod and done properly. However, I'd never do that to any of my machines I'd go the non-destructive route.

Personally, I don't see the difference between modding a case and modding the motherboard. For both, if it is done well and adds functionality/feature, then I don't see it as a problem.

This is especially true with the A1200 (with soldered CIA's) and the DF0/DF1 selector feature. You either mod the motherboard or you mod the case to achieve that.

[Daedalus]

Originally Posted by aeberbach

The point of removing the drive connector is to modify only the replaceable socket - if the signals are accessible without doing so that would be better, I only looked quickly at the PCB for this. I have never made holes or used glue or done anything that can't be undone when modifying an Amiga...

It's a 23-pin connector, so while they are replaceable, they're rare to find and only getting rarer. The resistor to remove on the motherboard, on the other hand, is a standard part available from any electronics supplier, and the floppy drive can be repaired with no ill-effects, or easily replaced. It's also easier to solder the resistor than the connector, though it does involve some fine soldering so you need a steady hand and decent tools.