Roland Quick Disk drives and FDS

Started by Skawo, September 26, 2022, 09:38:35 pm

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Skawo

Hi,

The other day I found a Roland S220 QD drive on sale for 5 bucks and snatched it up, thinking it would be great for spare parts for my FDS in case I ever needed them. Looking at it, it nearly identical to an FDS drive, and some questions did spring to mind;

1. The drive seems to have the elusive FD7201P chip. I was wondering whether an FDS 3602 could be swapped with it to get the drive to write disks, or do the FDS chips contain some FDS-specific logic?

2. If the chip _can_ be swapped, could the whole drive be swapped? The connector is different, but I did find the pinout for both the FDS and Roland connectors. If someone were to make an adapter cable, would the drive work in an FDS (using Roland quick disks)? It does appear that the Roland drive is missing the BATTERY SENSE and MOTOR SENSE pins, though...


I realize that this isn't probably something worth doing, but I thought it could be fun.

P

First, I'm sorry to say that I don't have any of the answers you seek, just my thoughts and speculations.

Second, that's a pretty neat find! I have been looking at QD-drives for MSX just for the heck of it but they have been a bit too expensive to pick up without a good enough reason, besides the disks are also not so common.

I would assume that the FDS disk drive is really just a stock Mitsumi QD-drive with a few simpler modifications to disallow disks without the FDS disk card shape and to disallow full disk writes. The fact that the FD7201P drive chip is a stock Mitsumi drive chip seems to fortify this guess, and I know that other systems using QDs uses the exact same density as FDS disk cards.
I'm have no idea if an FDS disk card can be read and written in a normal QD-drive, but if it can I guess it might be possible to use this drive in an FDS (and in that case any QD could be used with it).

I have no idea if the 3602 is pin-compatible with the FD7201P, but guess it could be possible if the 3602 is just Nintendo's ASIC containing a modified FD7201P to disallow full disk writes. You will want to be sure though.

The battery/motor sense pin is probably part of the power board of the FDS disk drive unit (HVC-022) which provides the power to the disk drive, and allows the software to know if the motor is on or not via this pin to the RAM Adapter. In the Roland the disk drive probably receives power directly from the main unit, but the Famicom's AC-adapter is most likely not beefy enough so Nintendo built a separate power board in the HVC-022 unit.
If you were to use the Roland drive with an FDS RAM Adapter you would also most likely need the power board to power it.

Tomy

FDS 3602 ? You mean FD3206 ?

I can confirm FD7201P can not be swapped with FD3206.

For FDS 3206 board, you need mod the board for compatible with FD7201P chip.

Skawo

Thank you for your thoughts!

Quote from: undefinedSecond, that's a pretty neat find! I have been looking at QD-drives for MSX just for the heck of it but they have been a bit too expensive to pick up without a good enough reason, besides the disks are also not so common.

Yeah, the only thing stopping me from doing this is the fact I've no disk to try it out with. Regular FDS disks do not fit and the carriage just refuses to lower. The disk is difficult to insert, as well, as if it was too thick.


Quote from: undefinedThe battery/motor sense pin is probably part of the power board of the FDS disk drive unit (HVC-022) which provides the power to the disk drive, and allows the software to know if the motor is on or not via this pin to the RAM Adapter. In the Roland the disk drive probably receives power directly from the main unit, but the Famicom's AC-adapter is most likely not beefy enough so Nintendo built a separate power board in the HVC-022 unit.
If you were to use the Roland drive with an FDS RAM Adapter you would also most likely need the power board to power it.

Well, naturally, the idea would be to make the adapter so that it can be put into a regular FDS, power board, and all. Will have to try to see what sort of readings the batt/motor sense pins give out. I'm thinking motor sense may be hooked to the positive terminal on the motor itself? Not sure.


Quote from: undefinedFDS 3602 ? You mean FD3206 ?

I can confirm FD7201P can not be swapped with FD3206.

Yes, I meant the FD3206.
And, oh. That's unfortunate.



I probably will end up trying this at some point if I manage to find a regular QD disk for cheap.
Here're some pictures of the drive in question if you're interested:









Skawo

October 03, 2022, 07:08:31 am #4 Last Edit: October 03, 2022, 08:33:43 am by rawrest
Having poked around some more, this is what I figure so far.
I guess the main worry would be the STOP MOTOR pin, then. Not entirely sure what to do about that, but maybe it would work without it, at least for games that never re-read the disk?

Not enitrely sure what the purpose of an express STOP MOTOR pin is, if there's already an ENABLE MOTOR one; wouldn't they just be the inverse of one another?




According to this perhaps the STOP MOTOR pin can be wired to the FD7201P pin 11?

P

Thanks for sharing this information and those pics. :) It looks so similar to the FDS disk drive, it's certainly a slightly modified version of the Mitsumi QD disk drive after all.
Too bad that FDS disk cards doesn't fit, but that was expected.

Regarding the STOP MOTOR pin, how is it wired in the FDS disk drive?

Skawo

October 05, 2022, 05:48:35 pm #6 Last Edit: October 05, 2022, 06:06:04 pm by rawrest
Stop motor is wired to pin 11 of the FD7201 on the FDS, but that doesn't seem right on the Roland drive, as that where the write gate goes.

Probably means that the code the FD7201 runs on the Roland is different, which makes it highly improbable this will work. Who knows, though - maybe it's similar enough that all it'll take is matching the connections.

Also, I found that if I force it, then an FDS disk will eventually manage to enter the drive. Don't wanna ruin mine, though, trying to attempt this with them.
I have ordered a QD disk, though, so I will be giving it a try in a few days. And if it doesn't work - oh well. Gonna make for a cool bootleg  ;)

P

I would guess there is more logic to the STOP MOTOR signal on the FDS somewhere on the board, but I don't know.

Skawo

October 06, 2022, 04:35:02 pm #8 Last Edit: October 06, 2022, 04:48:38 pm by rawrest
Seems like one of the on-board switches also stops the motor - probably the one at the end of the track. Perhaps I could wire up the signal to the output of that switch. Might not be (easily) possible, though, because it seems to stop motor signal is active on 0, instead of active on 1.

The QD disk will be here tomorrow, and I already got a spare power board to work on, so I'll be trying this tomorrow.

Skawo

October 07, 2022, 01:41:44 pm #9 Last Edit: October 07, 2022, 02:52:56 pm by rawrest
Well, I tried it, and it seems to STOP MOTOR pin is necessary, unfortunately.

The drive goes through its motions and the FDS Bios properly recognizes when a disk is inserted and stuff like that, but the motor doesn't return properly after reaching the end of the track. It DOES return properly when first powered, so that's not the issue...

I tried wiring the stop motor pin to various things, but, sadly, no dice.

Video: https://www.youtube.com/watch?v=0Pc-QOxQGjg


Oh well v:

P

Too bad, it's kind of satisfying to see it accept the disk at first though. Thanks for trying and sharing the experience.

Skawo

Maybe someday a broken drive will make its way onto ebay for a reasonable price to steal a board from ;)

Stephen

Perhaps try actuating the home switch with after a read is completed?

Skawo

I did try hitting both the head return switch and the one that gets hit once the carriage reaches the end. Sadly, the drive doesn't react.

I just remembered another detail; also tried this with an FDSStick, incidentally, and once the head gets to the end, on subsequent tries to read, the motor struggles for a bit trying to push the carriage even further forward before giving up. On the third attempt to do so, it finally goes back to the start position.

Skawo

Well, it's not quite what I hoped, but here it is, as outlined in the previous post.

https://www.youtube.com/watch?v=D1BSxiiWn8s