Internal floppy drive on iMac G3 - Firmware downgrade

[dougg3]

You're probably right -- I don't know of any OS 8 floppies. But no matter what, there's no way a New World Mac could boot from a floppy due to the Mac OS ROM file being too big. It's a moot point though, because the iMac was the only one that actually had a floppy port on the logic board

 

[onlyonemac]

I think I found an OS 8 disk tools floppy in Apple's archives (or I can email it to you since I've got it downloaded).

 

[max1zzz]

ok, sorry for takeing so long, been busy then had one hell of a time getting macrelix onto my imac's hdd.

List of drivers with rom 1.1.5 loaded (FDD connected, recognised, and reads discs fine)

Logging in with full privileges...

Welcome to MacRelix.

$ drvr
4: .Sony
5: .AIn
6: .AOut
7: .BIn
8: .BOut
9: .MPP
10: .ATP
40: .XPP
41: .AFPTranslator
48: .EDisk
49: .LANDisk
50: .Display_ATImach64_3DR3
51: .ATALoad
52: .DAVAudio
53: .ATADisk
54: .AppleSoundInput
55: .ASLM
56: .Infra
57: .SLM
58: .DSP
59: .ipp
60: .LeapIn
61: .LeapOut
62: .HDI
63: .swmdrvr
95: .PrinterShare
$

and with rom 1.4 loaded (FDD connected, but not recognised, and not reading discs.)

Logging in with full privileges...

Welcome to MacRelix.

$ drvr
5: .AIn
6: .AOut
7: .BIn
8: .BOut
9: .MPP
10: .ATP
40: .XPP
41: .AFPTranslator
48: .EDisk
49: .LANDisk
50: .Display_ATImach64_3DR3
51: .ATALoad
52: .DAVAudio
53: .ATADisk
54: .AppleSoundInput
55: .ASLM
56: .Infra
57: .SLM
58: .DSP
59: .ipp
60: .LeapIn
61: .LeapOut
62: .HDI
63: .swmdrvr
95: .PrinterShare
$

so, i guess it would be the .sony driver

just gotta get it loaded on os 9 now...

 

[olePigeon]

This is exciting.

 

[max1zzz]

Yeah it is can't wait to see what dougg3 (or anyone else) can come up with to get it loaded

 

[dougg3]

Thanks for testing that! That was very helpful...

Except I just realized that both the .Sony driver and the .MFMFloppy driver in the Mac OS ROM file identify themselves as .Sony in the DRVR resource they provide. The .MFMFloppy one just appears with that .MFMFloppy name in a different list. So the 'drvr' command returning .Sony still means it could be the .MFMFloppy driver. That driver has a date of December 1997 in ASCII, so I'm really leaning toward thinking that's the iMac floppy driver.

Tell ya what -- I'll package both of them up as extensions, and you can try them both. I hope it works, but no guarantees!

 

[max1zzz]

aswesome! can't wait to try it

Intresting that they both use the same name, guess it would make sense for it to be the .MFMFloppy driver, or maybe it needs both?

 

[dougg3]

OK, I have some extensions ready to test, just put one of them into the Extensions folder. I would start by trying these drivers with Mac OS ROM 1.2, and then if that works, maybe newer Mac OS versions will work too! No guarantee that either of these will work...in fact the real .Sony one crashes my G3 Blue and White (Mac OS 9.2) at startup, but the .MFMFloppy one at least loads and appears in the driver list in MacRelix.

Try either of them, but not both at the same time (they each load themselves as DRVR #4). For the same reason, do not run them with Mac OS ROM 1.1.5 or older (DRVR #4 is already in use on them)

Credit should go to bbraun for these extensions. I borrowed his DRVR loading/opening code from his serial disk driver. I'll be crossing my fingers!

Download the test floppy drivers here.

 

[max1zzz]

Ok, tested them, but unfortunatley no luck...

i'm testing on os 8.6 using the stock rom from it (1.4)

with just the MFM driver i got .sony in the driver list, but the floppy drive won't read discs and isn't recgonised

With just the sony driver i don't get .sony in the list, and the drive isn't recognised and won't read discs.

With both i get .sony in the list, but the floppy drive won't read discs and isn't recgonised

So i guess there is something else at work stopping it working in newer roms then....

But thanks for putting the drivers together, let me know if you can think of anything else that may be the problem, would still love to see this working on newer roms

 

[dougg3]

Eek, thanks for trying! Sorry it didn't work out. I'm not sure what to try next at this point. We're starting to reach the limit of what I know how to do

If anyone else is interested in figuring out what the heck needs to be done, the file I linked contains extensions with the DRVR resources I extracted from the Mac OS ROM file.

It's very interesting that the normal .Sony driver doesn't appear in the driver list if you use the Sony extension. I wonder if that's a clue. Maybe that one is indeed the correct one and it's having trouble loading for whatever reason.

 

[max1zzz]

i wonder if there could be something in the later Mac OS ROM versions that prevents the floppy from working, past just removing the driver?

I would have thought loading the driver would have been enough definatley odd it didn't work ....

 

[max1zzz]

Thought I would post something interesting I found today

Was trying to get some files on my PowerBook 1400, and hitting the problem of really bad floppies

Just to cheack the drive wasn't to fault I put in my 7.5 network access disk, and it worked, so out of pure curiosity I rebooted with the disk in the drive to see what happend. And you know what, it seemed to boot (but failed as the iMac won't run 7.5)

So maybe it is not the Mac OS rom containing the driver, but it blocking it from loading it from the firmware

 

[max1zzz]

And, on further investigation, there appeared to be no floppy driver in the imac's firmware, it's all in the Mac OS rom.

I found there is a 8.1 boot floppy, it is a disk tools one supplied with the 8.1 update on apples website, boots up the iMac fine

However it only boots if there is a hdd connected with Mac OS rom 1.1.5 (or earlier)

And further more, I got the firmware downgraded to work tried it annother couple of times, and eventually I got the progress bar and a message saying update successfull, but no change, won't boot the FDD without a bootable hdd connected and no FDD support under rom 1.4

 

[CC_333]

Well, still... Booting an iMac from floppy at all is a huge accomplishment!

It seems like downgrading the firmware isn't the answer; somehow getting Mac OS ROM versions > 1.1.5 to support that driver is the key.

Anyway, perhaps I can try this on my Rev. A/B; I did a lousy job soldering on the connector first time 'round, but this inspires me to try again!

c

 

[max1zzz]

Let me know how it goes, would be interested to see someone else try this

it dose indeed seem that patching the mac os rom is the way to go, i guess the first thing we would need to do is figure out why the extentions dougg3 made don't work, my guess would be there is something in later roms blocking it (rather than that they just removed the drivers)

 

[NJRoadfan]

What type of 800k disks are you trying to mount in 9.2.2? Also do you have file sharing enabled? Certain disk formats will not mount on MacOS 9 if sharing is enabled for some reason. I know this applied to ProDOS disks, don't know if it applied to any Mac formats. 400k MFS disks are not supported at all on OS 9.

 

[max1zzz]

There all HFS format, however it s not as simple as there not being read, the drive dose nothing what so ever, no head movement and it dosen't spin the discs, the exact same discs read just fine in mac os rom 1.1.5

 

[markyb86]

Just thought about this thread watching the latest Computer Clan video - and it looks like the prototype G3 imac doesn't have the unpopulated floppy pins, but does have and ADB connector on board

Thought it was funny that they added the floppy port on a later revision if it indeed was not there.

 

[Dandu]

The iMac has the floppy connector. The connector is on the image (the white cable).

And the ADB is on commercial Mac too, but unpopulated (like floppy). It's just more difficult to add it, there is many component to solder.

 

[Daniël]

Just thought about this thread watching the latest Computer Clan video - and it looks like the prototype G3 imac doesn't have the unpopulated floppy pins, but does have and ADB connector on board

I've commented on that video as a reply to the pinned comment about this, it does really show that Apple wasn't 100% sure they'd drop floppy, ADB and serial (which is technically still used for the IRDA in the Bondis) until late in development, given the headers are still there on the retail boards.

That said, I'm pretty sure that the iMac G3 Trayloaders had a really short development time. The fact they had regular serial and monitor cables strewn through the case to connect various parts of the computer together, seems like something Steve Jobs would have hated, him being the perfectionist he was. While I prefer the look of the Trayloader as it's very distinct, they do feel like a beta product, with the Slotloader being the final product that Apple really wanted to make in the first place.