Reading various format 5.25" floppies on a PC

From: Fred Cisin <cisin_at_xenosoft.com>
Date: Mon Jun 16 12:24:01 2003

Always start by being clear about whether you want to
duplicate a diskette of the other ("alien") format
read/write an image of the alien diskette
read/write files from the alien diskette
Use files from one program in another program


> I think there is some sort of program that actually copies floppy disks
> verbatum, right down to the bit patterns encountered, a true mirror image.

Teledisk may be what you want (No longer available?). But it will NOT
read Amiga, Apple, Northstar, single density, 128 byte sectors, etc.

ON A PC, using the PC hardware, a PC CAN NOT READ ANYTHING other than
"Western Digital" style MFM sectors on a PC, using PC hardware,
disunirregardless of what software you try.
But,... if you are willing to CHANGE the PC hardware AND write
software to accompany the changed hardware,... then anything is
possible.

> I know the Amiga software can be archived to CD-ROM, then manipulated by any
IFF you write the CD on the Amiga.
The PC hardware can not read Amiga diskettes, which are MFM, but do NOT
have the type of sector headers that the PC hardware needs.. That, of
course, is not strictly true. There was one fellow who claimed that by
interrupting it in mid read, that the PC could be tricked into reading
Amiga! But AFAIK, he never got it to work reliably. Kinda like when
Gallagher makes French fries using his sledge-o-matic - "I swear, you
gotta hit that sucker just right."


> PC that handles the ROM filesystem. Still, with the GCC encoding of Apple
> and Commodore disks, you might have a problem.

Yes. The PC hardware CAN NOT handle GCR. The PC hardware can ONLY handle
MFM sectors with "Western Digital Style" sector headers.

> Basic language programs can be easily saved as a text file, but ML might be
> a trick getting back onto a readable disk without a native CPU/System doing
> the work.
File content is irrelevant!
Files is files. All that you are after is the right sequence of bytes.
IT DOESN'T MATTER what the content is of the file.

OTOH, if you want to move a file from one disk format to another, then you
need software that not only reads the sectors/tracks of the
"alien" diskette, but also implements enough of its file system to be able
to parse the directory and understand it well enough to find the right
sectors for the file that you want.
That will give you an exact byte for byte copy of the file.

The CONTENT of the file is another problem. Text files are no
problem. But, many versions of BASIC "tokenize" the program for storage
(replace every "keyword" with an abbreviation), and the tokens are not
even the same from one version to another. But, as you said, you can
override that and save it as text. For example, if you want to move a
program from MICROS~1 BASIC version 4.51 on a CP/M machine to MICROS~1
BASIC version 5.0 on the SAME machine, you need to load the 0program into
4.51, save it as text, and load THAT into the new one.
If you DO succeed in getting a VisiCalc spreadsheet from an Apple disk
onto a PC disk, it will load just fine into the IBM PC version of
VisiCalc. But do you think that the current version of EXCESS^H^HEL will
handle it? If you copy a Wordstar file from a CP/M diskette to a PC, it
will load into the PC version of Wordstar; but will the _current_ version
of MICROS~1 WEIRD read files from the PC version of Wordstar?

"I can build a radio that receives broadcasts from France. It will get
all of the sounds EXACTLY right. But it doesn't TRANSLATE!"

There have been some programs for altering the content of a file for
transferring documents from one brand of word processor to another.


There have been some programs for transferring files from various MFM
diskettes to and from PC, including:
22DISK
Flagstaff (No longer available)
Hypercross (TRS-80 only) (No longer available)
Media Master (No longer available)
Oswego Systems (HP only) (No longer available)
Uniform (No longer available)
XenoCopy-PC (Available only by personally contacting the author)

Each handles a fixed finite group of formats. Most have provision for
adding in additional formats yourself, but almost nobody ever succeeds in
doing so, and after fielding too many "which numbers do I put in to make
my PC read Apple diskettes" the authors of the programs stop providing
tech support and HIDE that feature (in XenoCopy, try holding down
Alt and/or Ctrl when pressing the function keys, try format #0, etc.)


The Amiga has significantly more versatile hardware than the PC.
Central Coast Software made some stuff running on the Amiga for handling a
lot of formats (No longer available)


On the PC, it is possible to CHANGE the hardware into something more
capable, usually by installing another circuit board between the disk
controller and the floppy drive.
Apple Turnover (changed to "Turnover" at Apple's "request") (comes with
software for Apple ][ DOS, PRODOS, Apple ][ CP/M, Apple ][ Pascal,
etc) (No longer available)
Central Point Option Board (get the "Deluxe") (has software for Mac 400K,
800K) (No longer available)
Catweasel (there has been MUCH confusion between what it "CAN DO" (when
somebody writes software) v what it "WILL DO")) Tim Mann is the real
expert on it, has written great stuff for it, and knows which
software exits (it IS available!)

--
Fred Cisin                      cisin_at_xenosoft.com
XenoSoft                        http://www.xenosoft.com
Received on Mon Jun 16 2003 - 12:24:01 BST

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