Hi Jules, I replied yesterday evening, but somehow my e-mail did not show up (at least here). So, I resend it. Sorry if it hits the list a second time. 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 crystal 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 matter of how you write the software how to read the floppy. For instance, sector-wise or track-wise as the 1793 and 2793 have read-track commands. I would not use DRAM chips, but takje a single static 32kx8. Saves work on soldering and room on the board. 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 the Core Board is a 6809E instead of the 6502, I regard that's a plus !!! Handling double density will become tricky with the 6502, and even with the 6809, because of timing requirements (polling for DRQ is asserted). Single density can be handled by polling, but double density requires the use of IRQ or FIRQ or the use the SYNC instruction (need connect DRQ* to IRQ or FIRQ). I am waiting on the arrival of my 2nd BGMICRO order that has the 2793 ... gd luck, - Henk, PA8PDP 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.