MFM Floppy Drives?

[Ron's Computer Videos]

Has anyone here ever encountered a PC floppy drive on a Macintosh clone? The Tarzana motherboard design did make accommodations for a MFM style floppy drive, but I've yet to find photos of a board with those components installed.
Anyone seen one?

 

[Anden Selmani]

Technote for the LPX-40 motherboard
I don't think this was ever used on a shipping product. It would have greatly limited disk compatibility which probably would have not been seen in a positive light.
That being said, browsing everymac shows about a billion Mac Clones where the only graphic evidence of existence is a tiny thumbnail from the 90s.
There's probably a ton of clones that were scrapped because they looked like boring PC stuff.

The Starmax that shipped had a bezel without a cutout for the eject button.
Even the various prototype CHRP Macs seemed to use a Mac/GCR floppy.
hey look, MacOS 7.6 for CHRP. one of two known copies of CHRP MacOS... neither archived
Unreleased CHRP StarMax
Another Motorola Viper CHRP prototype

Supposedly the Gossamer G3 logic board (as seen on the 'beige' G3s) also has a header for a PC-style MFM floppy drive... under the Mac floppy socket. I haven't confirmed this though, nor have I seen any pictures or evidence that it's ever been tested.

 

[Ron's Computer Videos]

Technote for the LPX-40 motherboard
I don't think this was ever used on a shipping product. It would have greatly limited disk compatibility which probably would have not been seen in a positive light.
That being said, browsing everymac shows about a billion Mac Clones where the only graphic evidence of existence is a tiny thumbnail from the 90s.
There's probably a ton of clones that were scrapped because they looked like boring PC stuff.

The Starmax that shipped had a bezel without a cutout for the eject button.
Even the various prototype CHRP Macs seemed to use a Mac/GCR floppy.
hey look, MacOS 7.6 for CHRP. one of two known copies of CHRP MacOS... neither archived
Unreleased CHRP StarMax
Another Motorola Viper CHRP prototype

Supposedly the Gossamer G3 logic board (as seen on the 'beige' G3s) also has a header for a PC-style MFM floppy drive... under the Mac floppy socket. I haven't confirmed this though, nor have I seen any pictures or evidence that it's ever been tested.

A "Mac" with ISA slots is the real story here

Thank you for responding with all the great into - especially that dev note about the 4400!

 

[max1zzz]

Supposedly the Gossamer G3 logic board (as seen on the 'beige' G3s) also has a header for a PC-style MFM floppy drive... under the Mac floppy socket. I haven't confirmed this though, nor have I seen any pictures or evidence that it's ever been tested.

I'm about 90% sure the board in my beige DT has a MFM header on it. Maybe i'll try desoldeirng the Apple / GCR header and installing a MFM one since the G3 is really a parts mac anyway

 

[VicNor]

I'm about 90% sure the board in my beige DT has a MFM header on it. Maybe i'll try desoldeirng the Apple / GCR header and installing a MFM one since the G3 is really a parts mac anyway

What?! :O Pics or it didn't happen

 

[phunguss]

I'm about 90% sure the board in my beige DT has a MFM header on it. Maybe i'll try desoldeirng the Apple / GCR header and installing a MFM one since the G3 is really a parts mac anyway

Sounds interesting... let us know how it goes and I may try to duplicate. My G3 DT currently has a 450MHz G4 in it, overclocked to 533MHz.

 

[Ron's Computer Videos]

Sounds interesting... let us know how it goes and I may try to duplicate. My G3 DT currently has a 450MHz G4 in it, overclocked to 533MHz.
View attachment 21820

Sure, but it still needs a MFM compatible floppy controller chip.

 

[croissantking]

Sure, but it still needs a MFM compatible floppy controller chip.

The schematics indicate the Beige’s MFM floppy footprint is connected directly to the Heathrow chip. There is no empty controller chip footprint like on the Tanzania board.

 

[phunguss]

Found this in some documentation...

 

[Ron's Computer Videos]

The schematics indicate the Beige’s MFM floppy footprint is connected directly to the Heathrow chip. There is no empty controller chip footprint like on the Tanzania board.

Connect a MFM, power it on and stand back?

 

[joevt]

Open Firmware does contain code for MFM drives.

Open Firmware, 2.0.2 for PM 4400 and 7220 can choose between a MFMfloppy device and a swim3 device depending on some value read from a board register at offset 1a000 of OHare. There's a Open Firmware driver for swim3 but not MFMfloppy.

In Open Firmware 2.0a9 and 2.3 for Power Express, the device name is fdc instead of MFMfloppy and it has a Open Firmware driver.
2.0f1 and 2.4 (for Beige G3) is similar. The value that chooses which type of drive is connected is a register in Heathrow at offset 0x38 (feature control register bit 27 = MIO_OH_FC_USE_MFDC).

The name of the classic Mac OS DRVR is ".MFMFloppy" in all the above cases but also in other Old World Macs after Open Firmware 2.0 (PowerBook 3400c, PowerBook G3 Kanga, PowerBook G3 Wallstreet, PowerBook G3 Wallstreet PDQ).

New World Macs may have fdc but it's type is swim3.