Compact Mac Floppy Interchangability

[niccyb]

With the help of Byrd, I recently did a successful ROM switch from my 'dead analogue board Mac Plus' to my 'dead ROM Mac Plus'. Of course one mac had to lose, now I have a vegetable on my hands. I'm now considering doing another procedure on my 512k, which would be replacing the broken floppy drive with the Mac Plus one. Of course though, I'm not sure if this is entirely possible... I'm assuming that it would be (at least to some extent) possible, as I recall hearing that people have done 512k to 512ke conversions using a Plus floppy drive and Lo-ROM. As I have no spare ROMs on hand though, I'm wondering if the 512k would be able to utilise the double-sided 800k Plus drive as a 400k single-sided drive without causing complete failure/fire. Anybody have a definitive answer on whether they're interchangeable?

Cheers,

Nic

 

[Mac128]

Yes. The 512K will access the 800K drive as a 400K drive with the 64K ROMs. You can also format it as a bootable 800K MFS drive which is an amazingly useful thing! Follow these instructions, which will also explain the problem with the 800K drive cable. Unless you have a specific 800K drive, which blocks the PWM signal at the header, you will need another cable or mod the existing one.

However, using the HD20 INIT with System 2.1/Finder 5.0 and up will allow the 512K to write natively to 800K HFS drives and basically turn it into a 512Ke for all practical purposes, without the ROM upgrade. However, you MUST always boot from a 400K (or 800K) MFS disk, before you can use 800K HFS disks. The 64K ROMs will NOT recognize HFS disks before the HD20 INIT loads (as an aside, 400K HFS disks will not boot any Mac).

 

[niccyb]

Thanks for that Mac 128, I guess it's time to crack open the compacts again.