Possible to use "External Floppy (DF1)" as a DF0 ?

[Stedy]

To make DF0:/DF1: switchable with a real drive has a slight complication. You need a Motor ON signal.

Swapping SEL0/SEL1 for a Gotek or HXC drive is easy, that's all they use. The A500/A600/A1200 have SEL0/SEL1 on the internal floppy cable but crucially, only MTR0 (MOTORON on A500). This enable the motor, on drive 0 at the same time as SEL0. I tried connecting two drives to MTR0, nothing worked as they caused bus contention. icard At least I know why. The A1500/A2000/A3000/A4000 have logic onboard to re-assign DF0:/DF1:

According to the timing diagrams, SELx and MTRx go active at the same time so you may be able to connect SELx to MTRx on the Amiga floppy as well as the SELx input. If not pick off SELx and MRES from the 23 pin external floppy connector, generate MTRx + SELx to create MTR1 for a real floppy and use a long Reset (CTRL-Amiga-Amiga) to switch between Real floppy and emulated. That's the basic idea, it may need some tri-state buffers and a delay circuit (or microcontroller) to control the drive swap.

Ian

 

[BLTCON0]

I had the idea of making a DF0/DF1 switch that changed when you held down a mouse button on startup - similar to how some of those kickstart switchers work.
The idea was that you could hook up the gotek externally, keep the real floppy drive inside the amiga, and switch between them by holding down a button when you power on.
However I never found any info on how this was accomplished.

Got down to it eventually this weekend and designed something based on my equations. Not familiar with PALs/GALs so just discrete logic here. I'm including the schematic from the simulated circuit (sans power and decoupling). It works correctly in simulation, I'll build a prototype when possible to see how stable it is in action. You can give it a try as well.
All signals are active low. The flip-flop is positive-edge triggered, so the state of the left mousebutton is latched upon release of CTRL+A+A. Not pressed = standard mapping (S01 = S0, S10 = S1), depressed = DF0: and DF1: swapped (S01 = S1, S10 = S0).

Update: Prototype built and works fine, with full drive swap.

 

[asapreta]

I had the idea of making a DF0/DF1 switch that changed when you held down a mouse button on startup - similar to how some of those kickstart switchers work.
The idea was that you could hook up the gotek externally, keep the real floppy drive inside the amiga, and switch between them by holding down a button when you power on.
However I never found any info on how this was accomplished.

Got down to it eventually this weekend and designed something based on my equations. Not familiar with PALs/GALs so just discrete logic here. I'm including the schematic from the simulated circuit (sans power and decoupling). It works correctly in simulation, I'll build a prototype when possible to see how stable it is in action. You can give it a try as well.
All signals are active low. The flip-flop is positive-edge triggered, so the state of the left mousebutton is latched upon release of CTRL+A+A. Not pressed = standard mapping (S01 = S0, S10 = S1), depressed = DF0: and DF1: swapped (S01 = S1, S10 = S0).

Update: Prototype built and works fine, with full drive swap.

Very nice explanation and schematics.
Would you mind posting your full solution?

And sorry for reviving a more than 1 year old thread.

 

[Starglider]

I had the idea of making a DF0/DF1 switch that changed when you held down a mouse button on startup - similar to how some of those kickstart switchers work.
The idea was that you could hook up the gotek externally, keep the real floppy drive inside the amiga, and switch between them by holding down a button when you power on.
However I never found any info on how this was accomplished.

Got down to it eventually this weekend and designed something based on my equations. Not familiar with PALs/GALs so just discrete logic here. I'm including the schematic from the simulated circuit (sans power and decoupling). It works correctly in simulation, I'll build a prototype when possible to see how stable it is in action. You can give it a try as well.
All signals are active low. The flip-flop is positive-edge triggered, so the state of the left mousebutton is latched upon release of CTRL+A+A. Not pressed = standard mapping (S01 = S0, S10 = S1), depressed = DF0: and DF1: swapped (S01 = S1, S10 = S0).

Update: Prototype built and works fine, with full drive swap.

Any chance you would sell me one?