Re: High Density FD's

[spec@vax2.concordia.ca (Mitchell Spector)]

In article shack@deimos.frii.com (Randy Shackelford) writes...

>In article <12SEP199718271433@vax2.concordia.ca>,
>Mitchell Spector <spec@vax2.concordia.ca> wrote:
> 
>[snip]
> 
>>>BlueDisk formatted high density disks can be accessed by SuperDrive
>>>owning GS users, but its double-density format can't.  
>>
>>    Are you talking about 720K MFM disks? The SuperDrive can read
>>400K, 720K, 800K and 1.44 MB formatted diskettes (GCR and MFM).
> 
>For all practical purposes, you can't access 400K disks on a IIgs. They are
>all in MFS format, and the finder will tell you that the HFS FST doesn't
>do MFS and makes you eject the disk if you try to use one. I suppose though
>that you can format 400K ProDOS disks, but why do that?

    Yes you can. There is an Applesoft BASIC program called MacTransGS
(though despite the name, it runs on all Apple II models) that allows
you to read data from 400K MFS disks, the kind created by the original 
Macintosh 128 and 512. It works, I had a copy of Quicken 1.4 which
shipped on a 400K disk and read it just fine. The program is one way
only though, you can pull data off but not write to disks.

    Agreed. There is little reason to create 400K disks and considering
only two Macs in 1984 used that format (the Lisa 2 and XL did use 400K
3.5 disks, but they were not MFS format) it's pretty unlikely you'd be
coming across any MFS diskettes. The fact still remains though, you can
read/write to them using an 800K or 1.44 MB drive.

Mitchell Spector
spec@vax2.concordia.ca