ferdimh@gmx.de wrote:Yesterday evening I managed to capture first data. Since the stepper is was not active, I connected my Oscilloscope to the data output an moved the head by hand until I found a good signal. This is what I got (I shortened it) (Garbage) FF FF FF FF D5 AA 96 FF FE AA AA AA AB AB AB DE AA EB FF FF FF FF FF FF FF FF FF D5 AA AD 96 96 96 (many of them) B4 B4 B4 D2 D2 D2 (many of them)
It's almost impossible to get the sampling rate exactly in sync with the disk bytes that will always have some mechanical jitter. There are two approaches possible:
1. Brute force. Sample at a much higher rate, say 2 MHz and let the software figure it out.
2. Synchronize to the incoming data. That's what the EDD card is doing. Sort of a digital PLL that is being reset at the data pulse.
Talking about the EDD card. It's quite rare but is very easy to re-create. Either by just copying the design with 8 TTL chips or using a single CPLD to duplicate the functionality. The question is, does anyone still need it? Does the software help capturing protected disks to images? Duplicating protected floppies is probably not in high demand these days.
-Alex.