BMOW Floppy Emu

#1 Tue, 24 Feb 2015 - 03:29 68kMLA

I just got my floppy emu and I got my HD20 emulation working, but I am wondering if it will work on an un-expanded Macintosh 128K? I read somewhere that the Macn128K does not have enough memory to run HD20 Init. Has anyone tried it?

#2 Tue, 24 Feb 2015 - 07:24 68kMLA

In Larry Pina's book "Macintosh Repair and Upgrade Secrets", the author discusses fitting Mac Plus ROMs to a Mac 128 to use HFS floppy drives but does not mention the HD20.

Mac128 said:
[the HD20] can be formatted MFS, but requires by default that the HFS file system be loaded, or present in the case of the 128K ROM or later. This means it cannot be used on a stock 128K.

These two suggest that it may be theoretically possible, using the Mac Plus ROMs with the 128k, to use the HD20 ... but I can't find any evidence that it's been tried yet.

#3 Tue, 24 Feb 2015 - 18:13 68kMLA

I kind of want to keep it original so I don't want to replace any hardware. I thought the HD20 Init software takes care of mounting the hard disk for you, is it just the Mac 128K does not have the ram to run it?

#4 Tue, 24 Feb 2015 - 18:34 68kMLA

I think its a RAM issue. For the OS and init to load its tight. Part of the reason being you can not use a system like 1.0. You need 2.1 or better for HFS. The HD20 uses HFS and this was not introduced until 2.1 when the 512k was out. The Plus and 512ke, with updated ROMS that have the init, the HD20 can be used for startup.

But was there not a floppy disk made called HD20 startup? I could be wrong, but I thought it did some ninja work to load the init first then the 128k/512k could boot from it.

edit: I am not sure how the Floppy EMU works though for HD20. If its acting exactly like an HD20 you would need the init or ROM upgrade. If its acts like a REALLY huge floppy disk, then I am not sure. My guess if you need the init.

#5 Tue, 24 Feb 2015 - 19:37 68kMLA

Just try it and see - it won't hurt anything. I don't have a 128K myself, but from what I understand the HD20 Init will work just fine. But it will eat some RAM, and leave you with so little free RAM that you won't be able to run most programs.

#6 Tue, 24 Feb 2015 - 19:52 68kMLA

unity said:
But was there not a floppy disk made called HD20 startup? I could be wrong, but I thought it did some ninja work to load the init first then the 128k/512k could boot from it.

HD20 Startup

#7 Wed, 25 Feb 2015 - 06:11 68kMLA

Thanks I will give it a try on the weekend. Mac 128K with a hard drive, that would be cool.

#8 Wed, 25 Feb 2015 - 07:17 68kMLA

Yes it is cool. I have one right here.

128k ram is rather limited… but with PLUS rom's installed, it boots up the HD20 emu, just like a charm!