Hi, I came across the following message from Dave Dunfield from a couple of years ago during a search related to the Z80 i8272 home brew project I am working on. I recently got the i8272 FDC to reliably read sectors from a MS-DOS formatted 5.25" floppy disk drive. This project is underway but I am a long ways from completion. During the debugging of my system, I have noticed that there some possibly useful raw disk signals being generated by the data separator chip. These could be rather easily exported to support a disk imaging project were anyone interesting in such a thing. The signals are going *into* the i8272 (NEC 765) for processing and are raw data signals. The i8272 would not be used to process the data. This *potentially* opens up access to any FM/MFM encoded disk even hard sector. I don't know about other formats such as GCR, M2FM, RX02, etc. Here is what I propose; my SBC and Disk IO board generates intermediate product signals such as "separated clock", "separated data", "clock out", "index", etc and buffer them through a 74LS367 or similar. I am willing to make *MINOR* modifications to the Disk IO board to export these signals via a connector and even add one or two small chips to the design to improve signal quality. I am *NOT* willing to make major modifications to the design at this point as I have a mostly working system and do not want to start over. The intermediate disk signals could, *I believe* be imported into a PC parallel port with "clock out" (typically 500 KHz for MFM DSDD, 250KHz for FM, etc) being used for latch signal. I think they are also slow enough to be practically captured by the PC parallel port. The PC could then sample the parallel port at high rate (interrupt driven? DMA?) to read the signals and create a disk image from the data. Again, the i8272 would not process the signals so they would contain all the data the i8272 processes but will not pass along such as header info, IDAM, CRC, true gap length, etc. I could even include true "raw read" signal which would be the bit transitions straight from the drive however due to the high sampling rate required to accurately capture it I really don't think it would be much use. Would it be possible and/or practical to make a PC based disk imaging tool using the SBC as an intermediate stage? Please note, I am only offering to make minor modifications to my SBC and Disk IO board to support such a project, not to conduct a PC based disk imaging software development project myself. I wrote some hard sector Catweasel programs earlier for Heath, Vector Graphic, and NorthStar so I have some familiarity working with raw disk data, however, the home brew Z80 project is using up all my hobby time. If you are interested please reply here or contact me. Thanks! Andrew Lynch PS Here is the Z80 i8272 home brew project I am working on for background information http://groups.google.com/group/n8vem?hl=en Another disk imaging project Dave Dunfield dave04a at dunfield.com <mailto:cctech%40classiccmp.org?Subject=Another%20disk%20imaging%20project&I n-Reply-To=> Wed Aug 3 04:58:06 CDT 2005 * Previous message: ImageDisk and some 8' images posted * Next message: Another disk imaging project * Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] ________________________________ Hi Guys, I'm really getting fed-up with the limitations of the PC floppy disk controller. Here's another idea I've had on the back-burner for quite some time, I've mentioned to a couple of you during private correspondance, but here it is for open discussion. The idea is to make a small single-board computer with a microcontroller, a WD2793 or similar floppy disk controller, enough memory to buffer a few tracks, and a high-speed serial port for communication with the PC. The board would have connectors for 5.25"/3" drives and 8" drives, and would properly interface to all drive types. Firmware would be developed to provide read/format/write/analysis capabilities around the more powerful WD chip. Images would be transferred via the serial connection to and from the PC. This should allow us to archive soft-sector formats that are not compatible with the PC, and also to perform these functions under virtually any PC environment. I just haven't had time to design and build the board ... anyone else interested in working together on such a project? Regards, Dave -- dave04a (at) Dave Dunfield dunfield (dot) Firmware development services & tools: www.dunfield.com com Collector of vintage computing equipment: http://www.parse.com/~ddunfield/museum/index.html