Potentially interesting for reading floppy disks at a low level: Kryoflyx <http://kryoflux.com/>.
// Christian On 8 March 2015 at 02:14, Howard M. Harte <[email protected]> wrote: > Dave Dunfield's ImageDisk (.IMD) format can preserve the floppy disk > metadata. He has some DEC disk images in this format on his site: > http://www.classiccmp.org/dunfield/img/index.htm > > When I implemented several floppy disk controllers for the SIMH/AltairZ80 > simulator several years ago, I wrote a module for SIMH called sim_imd which > can utilize the ImageDisk format within SIMH. At that time, I had a patch > to make it work as an alternate to the flat file format that is normally > used for SIMH for the pdp_rx disk controller. I tested sim_imd with the > PDP-11 RT11 disk image from Dave's site, and it worked fine. > > I may be incorrect, but if I remember correctly, the RX02 disks have the > sector header in single-density and the data field in double-density. In > that case, I don't think ImageDisk will be able to handle it. If you hook > up an 8" floppy drive to a semi-modern PC motherboard with the right disk > controller, then you may be able to read at least RX01 disks with > ImageDisk. Last time I tried this was around 2008, and I believe I used an > Intel Desktop Board with Pentium 4 CPU and Shugart 800 drives. > > Only certain PC floppy controllers can read single-density, and even fewer > can write it. > > Preserving the sector headers is fairly important in my opinion. It > allows the image to be written back to a physical disk and used on real > hardware. That said, just getting the data off the disk in a flat file is > still very useful for most purposes. > > -Howard > > -----Original Message----- > From: Simh [mailto:[email protected]] On Behalf Of Johnny > Billquist > Sent: Saturday, March 7, 2015 4:52 PM > To: Alan Frisbie; [email protected] > Subject: Re: [Simh] DEC floppy disk interleave questions > > Hi, Alan. > > On 2015-03-08 00:47, Alan Frisbie wrote: > > I have a large quantity of disks that I wish to copy to files that can > > be directly used by the SIMH PDP-11 emulator and by the > > E11 emulator. They include 8" floppies (both RX01 and RX02), > > RL01, and RL02. > > > > The issue is that the disks have sector sizes that differ from the > > usual 512 bytes, as well as having interesting interleave > > and stagger factors. RX50 (and RX33?) disks have (I think) > > 512-byte sectors, but some odd track usage. I also believe > > that RX02 disks have the first track in single-density mode, just to > > complicate things, but it isn't used by most DEC O/S > > software. RL01 and RL02 disks also have bad-block sectors > > at the end of the disk. > > > > I am assuming that SIMH and E11 emulate the device faithfully enough > > that programs which are aware of the interleaving and > > small sector sizes will work properly. If this assumption is > > wrong, please enlighten me. > > > > If my assumption is correct, what is the best way to copy the raw > > disks (which are in a variety of O/S formats) to files which the > > emulators will be happy with. I can bring up a real PDP-11 with > > RX02, but will probably be using a microVAX-II with an Andromeda > > FDC11-B controller and Shugart 800 drives. I don't mind writing > > my own code with QIOs. > > > > I have a bunch more questions related to this, but this will > > do for now. :-) > > > > All of this is related to cleaning out my storage units and > > de-cluttering my life. > > Hmm, I believe this is not absolutely straight forward. The problem is > that simh (or E11) do not emulate the physical layer, but the logical one. > As such, the image files of disks are assumed to always be containing > sequential blocks, and no block headers are in the image file. > So, it will work, in that, if you can dump out an image from a disk, where > block #1 is block #1 on the image file, then things will just work fine. > If you dump out the physical blocks raw, including block headers, then > they are not usable by the emulators. > Logical rearranging of blocks will work fine, though. So, the trick you > normally see with RX01/RX02, where they remap block numbers to other blocks > numbers in the device driver, is just fine. You just want the actual > physical blocks, in the order they are on the disk. )As indicated by the > disk block headers.) The actual layout, as created when formatting the > disk, will not carry over, but it is also not important. > (I hope I'm making sense here, I feel I might be overcomplicating my > text...) > > Bad blocks, as described by the RL01/RL02 bad block tables, are totally > under the device drivers and system software, so that is just fine. > Systems will avoid those blocks, even on a dumped image of the disk, > assuming you copy all blocks, including the bad block list. > > Johnny > > -- > Johnny Billquist || "I'm on a bus > || on a psychedelic trip > email: [email protected] || Reading murder books > pdp is alive! || tryin' to stay hip" - B. Idol > _______________________________________________ > Simh mailing list > [email protected] > http://mailman.trailing-edge.com/mailman/listinfo/simh > > _______________________________________________ > Simh mailing list > [email protected] > http://mailman.trailing-edge.com/mailman/listinfo/simh >
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