Jump to content
Sign in to follow this  
Anonymous

Problem with FloppyEmu

Recommended Posts

Whenever I try to open certain .dsk files on the floppyemu, my Macintosh Plus says that the floppy has to be formatted and gives me the option of eject, one sided, or double sided. I can’t seem to fix this problem or find it anywhere online.

Share this post


Link to post
Share on other sites

First, try formatting the SD card and install a fresh driver (I know its called something else... cant think of it) for Mac. Try again? Make sure youre in floppy mode, and also, I dont believe you can open 1.44 HD disks on a Plus through a floppy emu.

 

I had a similar issue with mine and my portable. Certain disk images would bring up errors and not mount. I just used different ones.

 

Those floppy emus seem to be fussy at some times.

Share this post


Link to post
Share on other sites

Time to find the Applied Engineering AEHD+ and figure out what magic it used to make 1.44MB floppies work on the Plus....

 

IIRC, there's a big (for the time) honking FPGA in the thing.

Share this post


Link to post
Share on other sites
11 minutes ago, trag said:

Time to find the Applied Engineering AEHD+ and figure out what magic it used to make 1.44MB floppies work on the Plus....

The device required a driver, presumably it did something roughly akin to the HD20 (or Apple II SmartPort drives) and used the floppy data channel as a glorified serial port. Although, I dunno, I'm reading some Google Groups links that call it a "1.6MB" drive, I suppose it's also possible they used a trick like they did to make 1.44MB floppy drives work with the Amiga's built-in controller, IE, cutting the rotational speed by half, or a similar expedient.

Share this post


Link to post
Share on other sites

It was capable of reading and writing standard 1.44 MB floppies.    I guess it might also have supported some other odd size, but the point of the thing, IIRC, was to give the old Plus compatibility with the new big floppies.

 

Did it really need a driver?    For some reason I thought it was a bootable device, but my memories are old and flimsy.

Share this post


Link to post
Share on other sites

Drivers for it are in the various old mac software archives. I suppose it's *possible* they could have made it bootable by emulating/abusing the HD20 driver, since we know now that it's technically capable of handling arbitrary sized block devices, but I'd be surprised if that was the case. Seems like Apple pretty thoroughly kept the details of the HD20 protocol under their hat.

Share this post


Link to post
Share on other sites

The FloppyEMU speaks HD20 just fine; some of the quest to reverse engineer it touched this forum. But I can't think of any "contemporary" Mac product that used it, unlike the similar and copiously documented SmartPort protocol for Apple II family machines.

Share this post


Link to post
Share on other sites

Its driver may well work similarly to how the HD20 driver for the 64k ROM macs worked which was indeed overriding the ROM floppy driver with an enhanced replacement in RAM. (Basically the same driver the Mac Plus has in ROM.) Just color me skeptical that the AEHD+ can do that without a driver disk. (I mean, sure, it would be technically possible to have the drive emulate an 800k drive for the IPL and instead of booting directly off the mounted floppy it sends a "pre-boot" it has stored in ROM to the Mac that patches out the floppy driver and triggers a secondary boot, but unless someone has evidence it did that it sounds like a stretch to me.)

Share this post


Link to post
Share on other sites

Maybe someone can reverse engineer it and then we can implement whatever mechanism it uses in the Floppy Emu so the 128k, 512k, and Plus can use 1.44 MB images!

 

Not that it'd matter, of course....

 

c

Share this post


Link to post
Share on other sites

Maybe I'm missing something, but given the fact that the FloppyEMU already supports an HD20 mode that allows arbitrary size disk files and has a driver already present in the Plus (and 512ke) ROM why exactly would one really *need* 1.44 MB floppy image support? Why not just copy the contents of such images onto a hard disk image in an emulator (I believe vMac has no problem mounting them) and go to town?

Share this post


Link to post
Share on other sites

Well, yeah. You're right, of course. There's no valid reason why one would want to use 1.44 MB disk images when they can either create an arbitrary HD20-style image or copy to a hard drive of some sort.

 

However, it would still be kinda fun if someone figured out how to install a driver that allows an otherwise stock Plus to run a SuperDrive at full capacity (to accomplish this with the Applied Engineering AEHD+, they probably installed some sort of driver).

 

This is, of course, mostly an academic exercise, as the Floppy Emu, for all intents and purposes, renders most real floppy-based solutions unnecessary.

 

c

Share this post


Link to post
Share on other sites

Unfortunately, as far as I am aware, AEHD+ are rather rare.

 

I don't think anyone on this forum that is active actually has one.

Edited by Paralel

Share this post


Link to post
Share on other sites

The Outbound Laptop Model 125 also adds 1.44 MB floppy support to a machine with Mac Plus ROMs....

 

I have an AEHD+ in the attic somewhere...   Back when I got it, I opened the case, saw a giant (~88+ pin) PLCC FPGA and closed it right back up again.

Share this post


Link to post
Share on other sites

Someone might, but I don't.    What I do know is:

 

The floppy mechanism is a standard (unless stealth modifications were done) laptop style PC floppy mechanism manufactured by Citizen.  Between the floppy interface and the Outbound is a circuit board.   The circuit board contains an 85C30 (I think this handles whatever comm protocol that goes between the laptop and the floppy assembly), a WD37C65 floppy controller, a WD92C32 data separator, a 64Kb flash chip and a single 20 pin GAL PLD.  Oh, and there's a Xicor (XC9030, IIRC) digital potentiometer, which almost certainly plays some part in the variable speed control of the floppy spin speed.

 

On the Laptop itself, in addition to the Apple ROM on a SIMM, there are two 64Kb Flash/EEPROM chips which contain configuration code of some kind.  These chips are updated when the Outbound installer runs.   I know that they contain information on what internal device is installed (floppy vs. 20, 40, 60, 80 MB hard drive) and hte data is different for each size hard drive.   They could also contain an extended floppy control routine.  

 

All the components are fairly simple, and there's only the two places where code could be stored in Flash (counting the pair of chips on the Laptop as a single place).

Share this post


Link to post
Share on other sites

1.44MB support was the reason why I wanted to change out the IWM with a SWIM and then patch the ROM with the SE FDHD disk driver, but I never got around to it. I did by the rominator though. I dont know the differences between the SE and the Plus ROM to see if the Plus would boot an SE rom natively or not. If not, only thing possible would be patching .Sony

Edited by techknight

Share this post


Link to post
Share on other sites
1 hour ago, trag said:

Between the floppy interface and the Outbound is a circuit board.   The circuit board contains an 85C30 (I think this handles whatever comm protocol that goes between the laptop and the floppy assembly), a WD37C65 floppy controller, a WD92C32 data separator, a 64Kb flash chip and a single 20 pin GAL PLD.  Oh, and there's a Xicor (XC9030, IIRC) digital potentiometer, which almost certainly plays some part in the variable speed control of the floppy spin speed.

The Outbound only uses Plus ROMs, not an actual Plus motherboard, correct? I can't find any pictures of its innards, is it possible that the 85C30 *is* actually the comm port controller, they just punted it over to a peripheral controller board that also has the floppy controller on it?

If I had to hazard a guess I'd wager that the GAL/potentiometer combo emulate the IWM functions while the WD chips do the needful for MFM formatted floppies, IE, all together the mess basically does what a SWIM does. (But is undoubtedly not compatible with it in the slightest.) Disassemblies of the Mac ROM have revealed some hooks for intercepting the startup process and potentially inserting patches, presumably the Outbound leverages that mechanism to swap out Apple's floppy driver for one that can handle their homebuilt monstrosity. This is what almost every Mac emulator does so it's a technically feasible approach to the problem. (The same patching mechanism probably makes the same adjustment to the video driver to handle the Outbound's 640x400 display.)

Eit... One thing I am curious about is if the drive in the Outbound is actually fixed speed (IE, a completely unmodified mechanism) and that evil pile of bits that emulate an IWM take the alternate approach of varying the data rate instead, like Commodore 8-bit floppy drives did. Are there any jumpers soldered from the floppy drive's motor control circuitry to the Outbound bits? If not I'd guess that's what's going on.

Edited by Gorgonops

Share this post


Link to post
Share on other sites

That can't be the 85C30 for the serial ports, because the Outbound has serial ports and it doesn't always have a floppy drive.  There's only room for either an internal floppy drive, or an internal hard drive.   Not both.    So when the hard drive is installed, there is no 85C30 in the drive cage.  

 

Circuitry on the Outbound is a load of logic ICs and probably some PLDs, but nothing is much bigger than 20 pin DIPs.   I think there's an 85C30 actually on the board, though.   No 53C80 because SCSI is an external option.

 

I've always assumed that the Xicor chip is playing games with the voltage that drives the floppy motor to vary the speed in 800K mode.   I really need to create a schematic some day.   Without the controller board, the floppy mechanism is certainly fixed speed, and there are no special connections visible.    It's always possible that Outbound opened every floppy case and did surgery prior to installation....

Share this post


Link to post
Share on other sites
17 minutes ago, trag said:

I've always assumed that the Xicor chip is playing games with the voltage that drives the floppy motor to vary the speed in 800K mode.   I really need to create a schematic some day. 

Unless they modified the drive somehow I don't think there's any way you can just play with the input voltage on a standard Shugart/PC floppy drive and control the motor speed. Maybe on a really old full-height 5 1/4" drive that just uses a variable resistor in front of a conventional DC motor (but this is presuming that the 12v input is *only* driving the motor so playing games with the voltage on that won't screw with the other electronics on the board) but any 3 1/2" drive is going to use a brushless DC motor with a controller, which you'll have to hack to drive it at a non-standard speed. Not saying that the Xicor chip isn't supplying a signal to do that, but if it is that's no longer a stock drive mechanism with a standard pinout on the 34 pin plug.

 

32 minutes ago, trag said:

That can't be the 85C30 for the serial ports, because the Outbound has serial ports and it doesn't always have a floppy drive.

 

Maybe they're using SDLC as the communication bus to talk to whatever is plugged into that drive slot, be it either the floppy or hard drive module. Seems like a bit of a stretch but those chips are capable of running quite fast so it wouldn't be impossible. Although if that's the case then that definitely means that they must completely replace the Plus' floppy driver... and, honestly, I have other issues with this. If that board really just has the components you say and *doesn't* have some sort of microcontroller on it then I can't in the slightest wrap my head around why it has a ROM chip on it. (Part of a state machine that initializes the serial chip into a hardcoded transfer mode without needed a CPU?) How fat of a connector this to the main board? (Seriously, there don't seem to be *any* pictures of the guts of these things online.)

Share this post


Link to post
Share on other sites
2 hours ago, Gorgonops said:

The Outbound only uses Plus ROMs, not an actual Plus motherboard, correct?

Correct. They scavenged the ROMs from old Plus motherboards.

 

Quote

Disassemblies of the Mac ROM have revealed some hooks for intercepting the startup process and potentially inserting patches, presumably the Outbound leverages that mechanism to swap out Apple's floppy driver for one that can handle their homebuilt monstrosity. 

The original 64K ROM had a hook which checked $F80000 for another (usually diagnostic) ROM and jumped to it if it had the right signature. This hook was so early in the boot process that it was difficult to exploit. The 128K ROM in the Macintosh Plus retains this hook, and adds two more at locations $F80080 and $F80088. This last one is checked before the startup device loop, so a custom ROM could implement a driver and insert a drive queue entry.

Source of this information

 

3 hours ago, techknight said:

 I dont know the differences between the SE and the Plus ROM to see if the Plus would boot an SE rom natively or not. If not, only thing possible would be patching .Sony

The SE ROM is 256KB. The Plus motherboard can address up to 256K of ROM, so let's see what happens! But I bet the SE ROM is going to want ADB, which we know the Plus doesn't have.

Edited by Dog Cow

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×