Hi Jules, I have a design that worked - 20 years ago, with a 1793. It has a PLL-based data separator, using a 72LS629 and 2 4-bit counters, IIRC. I need to look it up. It was interfaced to 6809 bus signals, so changing it for 6502 is straight forward. I recently bought a few 1793 chips from BGMICRO, and then decided to make my design a lot simpler by using a 2793 as that FDC has a data separator integrated. With the correct clock cyrstal selection you can use the hardware for 3", 3.5", 5.25" _and_ 8" drives (under software control)! I am working on a 2793 which is piggy-back connected to the "Blinkenlight" Core Board which is based on the 6809E and has more than enough RAM and EPROM on board. But that's just a metter of how you write the software How to read the floppy. For instance, sector-wise or track-wise ! I started a webpage on this new project, see www.pdp-11.nl/ in the "my projects" folder. Vince still has Core Board kits (all parts included for $70), so the job is limited to the FDC part. (and the software ...) But it is a 6809E instead of the 6502, but that's a plus !!! Handling double density will become tricky with the 6502, and even with the 6809, because timing (read/write when DRQ is asserted) must be done by interrupt (FIRQ) or use the SYNC instruction. I am waiting on the arrival of my 2nd BGMICRO order that has the 2793 ... gd luck, - Henk, PA8PDP ________________________________ Van: cctalk-bounces at classiccmp.org namens Jules Richardson Verzonden: di 25-10-2005 20:14 Aan: On-Topic and Off-Topic Posts Onderwerp: Re: Looking for an 8 bit FDC... Chuck Guzis wrote: :-) I've certainly got 1770 chips lying around unused in the parts box... I think you've just put that at the top of the list :) Rationale: I'm interested in doing this in order to archive old floppies to modern media, and out of the 5 or so PCs I can lay my hands on at home, none are happy with FM data :-( Catweasel's ruled out on grounds of cost, lack of schematics, and the fact that it's an internal board anyway. I need an external box of tricks so that I can easily use it to do archival work both at home and at the museum (and potentially other locations too). I know the museum PCs have serial and parallel ports, but not all of them will have USB; plus I'm hoping to spend zero cash on this and just use parts lying around at home - I'll have various serial & parallel I/O chips but certainly no USB stuff! As an additional thought whilst writing this (admittedly not thought through yet!) serial might be nicer than parallel so that at some future date I can dump all of the necessary firmware onto the disk interface box's ROM and in theory just talk to it using a comms package from the PC host. Lots more work in terms of understanding the various download protocols to do it that way, and it means that the disk interface box needs to understand the resultant disk image format on the PC which I'm not sure I like... but it does mean that all the host PC needs is a serial port and some comms software (which is covered by pretty much any modern-ish PC OS on the planet) rather than any special application to drive the box. If serial's the standard interface though it'd be zero hardware changes to support this in the future - it just means being stuck with a slower serial protocol for disk image transfer, when parallel would be faster. And yeah, I think we've been over this on this list before... :-) cheers Jules This message and attachment(s) are intended solely for the use of the addressee and may contain information that is privileged, confidential or otherwise exempt from disclosure under applicable law. If you are not the intended recipient or agent thereof responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this communication in error, please notify the sender immediately by telephone and with a "reply" message. Thank you for your cooperation.