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Emax OS creation primer
2014-02-04 by geektech207@...
There's an article on the web about how difficult it is to write an emax OS to floppy, and the author described the symptoms of the emax reading about 3 tracks / clicks in and then the LEDs flashing, and then a continual retry:
http://forums.nekochan.net/viewtopic.php?f=8&t=16724547
The author was questioning if the utilities worked, or if the OS images floating around were invalid. Reasonable question, so I wanted to clarify one way that I've successfully gotten OS images to write correctly.
I have tried EMX for DOS on an older desktop with a single internal floppy booting to Win98 DOS. This program appeared to work correctly. The disk would even validate after the write. It would format and write an OS without error, but when placed in the emax, the symptoms were the same as the article I linked to. Perhaps it works best in 386/486 machines with true 720K drive (instead of 1.44M), I'm not sure, but I have had absolutely ZERO success with this utility under ANY circumstances.
There's another program called EMAXUTIL which is simply a scaled down version of EMX (by the same author). Same story.
I have tried Omniflop / EMXP on a Pentium 3 laptop running XP which has an internal floppy bay. EMXP and Omniflop both interact with the disks and seem to work without error, but again, the emax ultimately will not boot. So beware of laptops, even if they seem to have an internal drive, it's not necessarily the same standard as a desktop internal drive. USB drives won't work, of course. That goes without saying.
The only winning combination I have had is with a Celeron desktop with 1.44 internal floppy running XP. Omniflop FDC and floppy disk drivers are both installed. Format the floppy using the "emax [standard]" parameters. Then use EMXP to write an OS file to a DD floppy. 1,2,3 head reads on the emax and then: SUCCESS! Emu Emax boots up correctly!
There's another "emax [1024 sector]" option in Omniflop. This format cannot have an OS written to it, so make sure to avoid it. Also, true DD floppies are no 100% necessary. The HD with tape over the hole CAN be successful with this method (maybe not viable in the long term, but it can work.)
The moral of the story is that, yes, it IS possible to use a PC to write an emax disk. It's not easy, but it's doable. It can very easily (and persistently) appear that your emax floppy is dead, dying, or out-of-spec with other drives, but that's not necessarily the case. Make sure you've got good floppies, PC drives, software, and technique before writing off your emax drives!
Some of this equipment and software I have used to successfully write Ensoniq disks, etc. and yet it still failed on the emax disks, so don't make the mistake of assuming that just because it's tended to work under similar circumstances that it will all work properly under this specific instance.
The symptoms in the article (three reads and then LED flash loop) seems to occur when the disk is ALMOST in spec and has an OS on it. ** I would be interested in knowing the precise technical reason why this is occurring. Anyone know what the missing ingredient is?**
The emax behaves differently when a totally blank disk or an emax formatted disk without an OS is inserted. "Read Error!" error message can occur with a non-emax disk, and will have continual drive access. Where as an emax formatted disk with an OS will say "Loading Software" and have continual drive access. "Please Insert Disk" will occur when there's no drive (obviously).
A correctly written emax OS disk should load promptly, probably after just 3 head reads.
Also of note: You can format an HD disk without putting any tape over the hole when using the emax itself. The drive will write to and boot from an HD disk. It simply treats it as 720K (or 800K by emax standards) no matter what, unlike a PC drive that needs the hole to distinguish between 1.44M and 720K.
Good luck!!