IIgs Networking Boot Disk

[Bunsen]

Fixed the image in the OP.  Original here.

 

[Bunsen]

The cheaper (~$20) older versions of the Raspberry Pi would be plenty enough power to run A2Server:
 

Update 9-Nov-15: A2SERVER 1.2.5 is available. It has support for Raspberry Pi 2 Model B and every other Raspberry Pi

... which is making me wonder why I spent ~$100 on an IDE card.

 

[Gorgonops]

HThis means that (I'm pretty sure - I've seen TOS 2.6 or something ROM noted as a limitation, though) the machine can at least in theory read HD disks.  I don't know precisely what that means.  However, there's a floppy to Smartmedia adapter that (as I understand it) allowed the use of HD floppy drives as scalable smartmedia readers - and could be used on any HD drive at least in theory.  I'm seriously inclined to try that on the ST if I can actually use HD disks.

Only the very late "Mega" STs have a controller capable of using high-density floppies "out of the box". There are mods out there to overclock the controller in earlier models to the requisite data rate but they come with gotchyas.

In any case, those Smartmedia readers for floppies don't work without a driver. To make a long story short, you know these things?

Those SmartMedia cards use the read-write head in a floppy drive the same way, *BUT* they don't actually emulate a floppy disk. The driver is necessary to make the host system understand that it's just using the floppy controller as a data channel over which high-level commands are sent to communicate with the storage device.

So...

I'm also then inclined to try it on some Macs, and then - to cycle back - I think I've read about HD floppies on IIgs.  I'm assuming it was a single card that's obscenely rare and prohibitively expensive?

It also won't work in Macs, not unless you have a driver for it.

And, high density floppy drives for the IIgs do indeed require a special controller. Apple made one, which is indeed rare and expensive and has to be paired with a Macintosh "SuperDrive" external floppy, and there were also third-party ones that worked with normal Shugart drives. (Those might be cheaper, if you can find one, maybe?)

 

[raoulduke]

Darn.  I was under the distinct impression you didn't need a driver...  I was having trouble making that logical leap, and this would explain why.  Since that'd be the only real utility, screw it.  [Either way I figured that solution wouldn't work for the IIgs.  Interesting that the adapters exist, but a cursory search suggests I'm not going to want to pay for one.  As for [this] ST, the drive works and it is an HD drive [sFD-321B rev WT-05], but I'm not sure if the ROM will support it; I'd guess not but we'll see when I get a chance.]

 

[Gorgonops]

As for [this] ST, the drive works and it is an HD drive [sFD-321B rev WT-05], but I'm not sure if the ROM will support it; I'd guess not but we'll see when I get a chance.]

HD floppy drives are usually compatible with DD controllers *in low density mode*, that's not the problem. The question is whether the controller in your ST physically supports the higher data rate. That is literally the difference between DD and HD capable controllers, the bits are clocked twice as fast (500kbps vs 250kbps) when working with an HD disk. If your machine lacks the ability to clock the controller chip at two different speeds then it's not going to work with HD disks. (Again, unless it's modified; the post I linked to describes what is essentially an overclocking mod that will make an older machine capable of the 500kbps data rate but it doesn't work perfectly because it overclocks other things that really shouldn't be and causes issues with reading DD disks.)

One oddball exception: They sold special HD floppy drives for Amigas that worked without changing the controller, but the drives *themselves* spun at 150 RPM instead of the normal 300 RPM when an HD disk is inserted. DEW THE MATH and you'll find it's the same effect.

 

[raoulduke]

No I know; and the guy who helped me with the mod indicated that removing the HD sensor would force it into low density mode.  But as I said I don't think that matters, I would guess this machine cannot support it.  I think I misread this post, which was where I was getting the 2.6; you need to replace the floppy controller and then probably also need TOS 2.6; that makes sense.

*Oh wait, lol, I already knew it couldn't do HD; the format options are one- or two-sided.

 

[Gorgonops]

You could just stick a piece of tape over the holes in the disks rather than mangle the drive if your goal is simply to format high density disks with a low density format. (Or maybe stick a piece of tape in the drive if you want it to be permanent.) It should work "correctly" with real low-density disks regardless of whether the sensor is there or not.

I am wondering about that bit about disk change detection the other forum post talked about. Hopefully your new drive does that right, otherwise you may corrupt disks after a swap.