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Model II,12,16,16B,6000 8" to 5.25 Inch floppy adapter cable 50 pin to 34 pin

JonB

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Would like to
- connect 34pin drives to the MII
- choose which is drive zero internal/external
- disable internal drive entirely
- all with switches or links

:) pretty please :)
 

NF6X

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I don't think that a micro or any other active circuitry should be needed unless some deluxe feature is wanted. FDADAP needs to monitor the track number to generate the precomp signal, but that is not needed in the other direction.

I think it should have a switch or jumper to select single vs. double sided mode. Maybe just a plain old jumper, which a user could connect to a remote switch if desired?

I was also thinking it could be handy to have an option to remap drive selects if needed. Maybe just a convenient set of through holes to let a user cut drive select traces and then remap them with wires or a DIP header or something?

Frank Durda recommended just strapping things to keep motors on all the time in order to keep the cable simple, but I would rather make that jumperable for use with drives that support smarter motor control. I need to look into the details.

What else am I missing?
 

NF6X

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JonB: I would also like to select internal vs. external in order to boot from either the internal drive 0 or an external Lotharek emulator. I think that might be a different board, though, vs. a plain old 50 to 34 adapter. I think it would need to be inserted inline with the internal floppy cable in order to remap DS0. Or maybe this could be handled best with a PAL replacement that swaps the internal vs. external cable mapping? Let's brainstorm this some more, but I think it will be a separate thing vs. a plain inverse-FDADAP.

Edited to add: Might also want to do things differently for a Model II vs. the later machines with slimline DS drives? I need to study the II schematics.
 

Chromedome45

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Ok some note on my confusion. (so what else is new!) I thought the internal hard drive was mapped to 0 and the floppy to DS1. When I was cleaning my 8" drive that what I observed about that drive. Didn't check HD to closely. @JonB has some good ideas! Also I say KISS as the old saying goes! If a microcontroller is not needed so much the better. Also should a stand alone entity no other boards (FDADAP) needed.

Tomorrow I am planning on getting a proto board and some stacking pins at the electronics surplus store near me.

This place: http://www.skycraftsurplus.com/
 

NF6X

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The hard drives and floppy drives are on separate and mutually incompatible interfaces. Drive letter mapping happens at the operating system level, but at the electrical level, drive select numbers are unrelated and independent between the floppy vs. hard interfaces.

On a 6000HD, I guess it would make sense to install the jumper to map DS1 to the external interface, since the hard drive occupies the physical space where a second internal floppy drive would be installed (I think).
 

NF6X

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Do you guys have a preference for vertical vs. right angle header connectors? Does anybody strongly dislike the fancy ones with latch/ejector levers?
 

kb2syd

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Sorry, all of this is stuff I take for granted. I was working on these machines when they were new...

For the floppy drives on the model 6000 (and 16b) - DS0 is not available on the external interface. DS1 is not by default in a 2 floppy drive system, it is if the system originally shipped with an internal hard drive.

Floppy and Hard drive selects are independent. Something so obvious for those from the trenches, but so easy to get confused about today.

HD DS0 and FD DS0 are not related at all.
 

pski

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I thought the internal hard drive was mapped to 0 and the floppy to DS1.

The internal hard drive is drive 4. The MII boot rom looks for a drive 4 and will boot from there before prompting for a floppy to boot from in drive 0.
 

kb2syd

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The internal hard drive is drive 4. The MII boot rom looks for a drive 4 and will boot from there before prompting for a floppy to boot from in drive 0.

It is logical device 4. It is still DS0 on the hard drive chain. Don't be confused by logical device numbers and digital device IDs. The hard drives where DS0 through DS3, same for the floppy drives.

In xenix they were /dev/fd0 and /dev/hd0 (and /dev/root).
 

NF6X

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To further add to the confusion, I'm finding that floppy drive manufacturers and Tandy didn't agree upon whether to call the drive IDs DS0..DS3 vs. DS1..DS4.
 

kb2syd

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To further add to the confusion, I'm finding that floppy drive manufacturers and Tandy didn't agree upon whether to call the drive IDs DS0..DS3 vs. DS1..DS4.
That's been going on forever. Does counting start at 0 or 1. If your drive is numbered DS1 through 4, subtract 1 in Tandyland.
 

Chromedome45

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Sorry, all of this is stuff I take for granted. I was working on these machines when they were new...

For the floppy drives on the model 6000 (and 16b) - DS0 is not available on the external interface. DS1 is not by default in a 2 floppy drive system, it is if the system originally shipped with an internal hard drive.

Floppy and Hard drive selects are independent. Something so obvious for those from the trenches, but so easy to get confused about today.

HD DS0 and FD DS0 are not related at all.

So you are saying that the external drive must use ds1 if jumper is shorted on motherboard? I have a 6000HD. Please clarify if you can. Sorry for all the dumb questions. I feel like a total newbie on these machines. Even though I had a model I back in 1978.
 

NF6X

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So you are saying that the external drive must use ds1 if jumper is shorted on motherboard? I have a 6000HD. Please clarify if you can. Sorry for all the dumb questions. I feel like a total newbie on these machines. Even though I had a model I back in 1978.

  • The boot floppy drive, DS0, is always on the internal floppy cable.
  • Floppy drive DS1 can be either on the internal floppy cable (jumper E40/E41 removed) or on the external floppy cable (jumper E40/E41 installed). Since you have a 6000HD, I think it makes sense for you to install jumper E40/E41, allowing up to three drives to be on the external cable.
  • Floppy drives DS2 and DS3 are always on the external floppy cable.
  • In all cases, each individual drive needs to be jumpered to respond to the desired drive select signal.

Does this help?
 

NF6X

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Here is a first draft schematic for a simple 8" controller to 3.5"/5.25" drive adapter. It is not yet feature-complete, as I still plan to include some cut-and-jump capability for the drive selects. I'm sharing this for review, proofreading, questions and comments. What do y'all think?

https://dl.dropboxusercontent.com/u/29876211/fd50to34-draft-01.pdf

This would be a small board with two male headers for connection to plain old IDC ribbon cables. Maybe something like this:

fd50to34-draft01.jpg
 

Chromedome45

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  • The boot floppy drive, DS0, is always on the internal floppy cable.
  • Floppy drive DS1 can be either on the internal floppy cable (jumper E40/E41 removed) or on the external floppy cable (jumper E40/E41 installed). Since you have a 6000HD, I think it makes sense for you to install jumper E40/E41, allowing up to three drives to be on the external cable.
  • Floppy drives DS2 and DS3 are always on the external floppy cable.
  • In all cases, each individual drive needs to be jumpered to respond to the desired drive select signal.

Does this help?

Yes it does Mark.
 

Chromedome45

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Mark:: Your simple 8" adapter looks good. May have to test it out when I get those parts tomorrow. Make a kind of prototype! If I have your permission
 

NF6X

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Yes, I'll make it available at OSH Park, and the design files (Kicad) will be open.

If I put the headers on opposite sides of the board, then routing will be much neater. Does this look too hokey?

fd50to34-draft02.jpg

Also, I'm particularly interested in feedback from smart folks about the motor control configuration. The Frank Durda way is to ground the motor control line to force the motors on all the time. I tried adding some more options for use with compatible drives, but I don't know if they make any sense.
 

Chromedome45

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I did splice together 2 floppy cables a 50 pin to a 34 pin although I did not have much luck getting it to work the motor was off until I inserted a disk and closed the drive latch. Then the motor came on. Sounds like that is what should happen. So I think.

Also even with an external drive configured as drive DS1 the system will always want to boot the internal drive no matter what. So I can't boot from the external unless I hook it up to the internal connector? Which makes sense. Then put the internal drive on the external connector? Then boot the 5.25 connected to the internal connector. And the 8" will be the external drive as DS1. The I can transfer files from the 5.25 to the 8". Or am I way off course. Let me know.

Mark: is the PDF schematic current? I was wanting to build an adapter according to your diagram.
 
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