Home Page Forums MAME MAME MAME support for writable media

You don't need posix level if you only read or write whole files. And in practice we already have the interface and implementation for a couple of filesystems. Some stuff could be added still, like defrag, but there's enough to try a first UI anyway.

could we get .dlt delta files holding a delta vs an actual floppy image? that way an original image isn't modified at all on disk, but the delta is applied to it on load if it exists in the same(?) directory as the image.

We have diff files like that for CHDs. They work great for fixed-original-image (arcade games and software lists), and are a bit of a nightmare for everything else.

Delta files are not really interesting for floppy images because they're too small for the delta to matter. Delta-like behaviour can be interesting (and is halfway-implemented, sorry), where mame "magically" remember the changes done to an image that is not actually changed, especially if it's in a zip.

Anything that can be turned on and off as desired is good for me.

With diskettes there definitely needs to be a 3rd marking to distinguish "bad" from "inaccurate" dumps, because areas outside the actual files often only matter for copy protected disks or bootblock position, so the indication should make it clear if the disk image does function or not.

With downloaded content or type-in listings from magazines the binary structure does not matter anyway, so there is no "master copy" to reproduce. Other diskettes often have bad blocks outside the actual files.

My main PC is a severely modded Highscreen Colani bigtower (DFI K6BV3+/66 mainboard with AMD K6-3+@550MHz, 768MB RAM, 2 genuine ISA soundcards, DVD writer, 160GB HDD, running Win98SE) which has a 1.44MB 3.5`` and 1.2MB 5.25`` diskette drive. Nowadays I have installed at its ceiling an additional modern ITX mainboard (Ryzen 2400G, 16GB RAM, 8TB HDD, DVD writer) for Linux Mint and Win10, so I first time have enough disk space to dump some 100 of my CDR (containing e.g. tons of downloaded ancient web pages about tech stuff etc.).

I am working through some hundred of my PC diskettes to preserve their contents. Some indeed were unreadable; particularly one brandless 1.44MB sort (black with white "HD" logo and too small paper sticker with cyan lines) tends to fail, and also 5.25`` things written with 360KB drives (ancient 286 and CPM machine at school) are partially unreadable. Often I have to carefully clean the surface with cotton swab and isopropanol (let it fully evaporate, else the surface is softened and gets scratched) and insert cleaning diskette with a drop of isopropanol between read attempts. Also rhythmically pressing the thumb on the front of the diskette can help to read bad blocks on warped disks. I had taken apart the external 3.5`` diskette drive of my IBM Thinkpad 760XD to rotate the head motor into different positions, which helped to recover a few more files.

(In former times my first PC was a 286 and later 386SX bridgeboard inside my very modified Amiga workstation (A500 in huge wooden case with handsoldered adapters, internal A570 CD drive, SCSI card for Iomega 20MB sort-of diskette drive etc.). At hat time I had often manually adjusted diskette heads because school diskette drives all seemed to be misaligned or dirty and so wrote incompatible diskettes, which e.g. made it hard to use downloaded files (through DOS ftp at school, had no internet at home). Thus many of my diskettes seem even worse misadjusted than original payware or shareware ones.)

For reading, I yet have only DOS mode of Win98SE for file copy (unlike windoze it allows infinite retries), a primitive track reading program disktool.exe and procopy.exe to mage binary images and check which blocks are unreadable. Bad with these tools is that they tend to replace unreadable tracks with random copies of previous tracks (likely garbage from a ring buffer), which makes them hard to identify in a hex editor (e.g. to merge multiple bad dumps).

I e.g. still have some unreadable 360K 5.25 CPM/86 disks from my practical course, those were likely written on a Siemens PG675(?) industrial computer (resembling an Osborne PC with internal green CRT), which was used to program Simatic PLC hardware.

https://forums.bannister.org/ubbthreads.php?ubb=showflat&Number=106592



https://forum.classic-computing.de/forum/index.php?thread/15021-siemens-pg675/
https://en.wikipedia.org/wiki/Simatic
https://de.wikipedia.org/wiki/Simatic

The crazy thing is that there were some games on this computer. E.g. there was a textmode clone of "Qix", of "Centipede", of "Nibbler" and of "Ork Attack" (?, you had to move left & right to defend a castle by dropping stones on enemies those built ladders to climb up a brick wall); the latter even used a redefined charset but AFAIK none of them had sound. And I think I had copied them on my floppy.

My dump with disktool shows in HxD fragments of recognizeable words (e.g. file names) but likely nothing complete. At secondary school we also had on Commodore 286ers a CNC turning lathe and milling machine simulator (terrible DOS program that crashed with "division by zero" when moving the tool out of range), of which I still have diskettes with the code I wrote. But the disk with compiled code (for an actual Heidenhain milling machine?) is unreadable like when the disk wobbles eccentric and so only reads half of each track. But I guess it is the different head geometry that makes the Mitsumi 1.2MB drive of my Colani bigtower fail to read it.

Reading strange 5.25 floppies?

Is there a program to read 360K (or lower?) DOS or CPM floppies in an Atari XL or Commodore C64 floppy drive, to convert it into a PC readable format? Eons ago I used a DOS serial port adapter (SIO2PC) to communicate with Atari 800XL and C64 to read and write their disks. Else I likely need a 360k PC drive. In a box of old parts I somewhere had a belt-driven double-height 5.25 drive full of DIL ICs (found in fleamarket scrap in 1990th) but I doubt that it works and have no clue what connector it uses and if it ever could be connected with PC hardware. It may have been gutted out of an Apple II or such.

360K PC disks are double-sided, which Atari and Commodore drives are not.

The Commodore 1571 disk drive is technically able to read double-sided DOS or CP/M floppies (at least from what I've read, I still don't have one myself), but there is no dumping software for the C64/C128 that I know of.

Also, you might probably have better results if you dump the floppies with one of the sophisticated dumping devices like a KryoFlux, FluxEngine, SCP or similar. I have dumped dozens, if not hundreds of old 360K disks and have not come across one that at least one of my two 5.25 HD drives could read. I'm having more trouble with old 3.5'' HD floppies to be honest...

But with 360k 5.25 diskettes AFAIK a 1.2MB drive is often incompatible due to different magnetic field geometry. It may even be that I have a Commodore 1571 somewhere in my parent`s house (in another city). Kryoflux seems quite expensive. But I am still daily using my Amiga and own a lot of other homecomputer diskettes, so something like Kryoflux might be useful, if it can convert the resulting image file. (AFAIK its native format is a kind of 50MB WAV file sampled of each track that can be only written back to diskettes but not used in emulators.)

1.2MB drives can work in DD or HD mode – it’s software selectable. The disk will be ruined and need degaussing if you try to format it in the wrong mode, but the drives support both.