keith
Well, I’ve written my first .adf tonight! I threw together a quick routine on the PC side to query the SX for both sides and all the tracks. It generated a 901,120 byte .ADF file of a disk I had called...
sync’ing to the 0x4489 0x4489
Well, this wasn’t as easy as I first imagined. There are some issues: 1> By the time you’ve detected the 4489 4489, it’s too late to do much about it. This is because I’m writing one bit at a...
new isr thoughts
While this new ISR is indeed easier to understand and much more simple, I can’t help but remember what else my ISR used to do for me. The four things I really lose are: 1> Any type of double 1’s protection...
Anatomy of a flux transition
I wanted to put up an image that displays an actual flux transition pulse coming off an amiga floppy disk whose data was encoded in MFM.
CLICK ON THE IMAGE TO DISPLAY A FULL RES VERSION.
Timeline
I’ve put together a time line of events starting from November 2004, the initial idea.
CLICK THE ABOVE IMAGE FOR A FULL SIZE VERSION.
adding more commands
Now that I *think* I’ve got a handle on the reading portion, I’ve been adding a couple more commands. I added support so that the SX knows what cylinder number it is on. The F and B commands increase and...
Logicport screenshots and project file
I thought this might be neat to put up. Sorry about the high-res image but you lose too much when it compresses it. Click here for the screenshot. Also, I uploaded the .LPF project file which can be viewed for free with...
Found one issue
Well, within an hour or so of getting my new LogicPort logic analyzer hooked up, I’m at least noticing some symptoms that I haven’t seen before. The drive is putting out(or the logic analyzer and my sx is...
Intronix LA1034
I’m seriously looking at the Intronix LA1034 logic analyzer. It’s a USB PC-based logic analyzer. 34 channels, samples up to 500mhz, and has nice trigger options, etc. I’ve downloaded the software...
pullups
These are all 2us per division on the scope. Top trace is the actual MFM, bottom trace is the entering and exiting of my ISR. You should see an entry into the ISR for every falling edge, and every ~2us afterwards. 1k...
mid-january status
So here’s where I’m at: I know my memory read and write routines are good. I calculate a checksum as I’m writing the data, and on the output of that data to the PC, I also calculate the checksum. ...
revisited memory routines
I was looking over my reading and writing routines. Minimums for the fram are Clock high min. 28ns Clock low min. 28ns Data setup min 5ns I write in two places: First, when bits are coming in from the drive, and the ISR...
simplified ISR
It looks as if I spoke too soon. I’m still having reading problems. The data used to be forced into an MFM mold, but all that’s done in some cases, is to further corrupt the corrupt data. I rewrote my ISR...
Samsung SFD-321B 3.5″ floppy drive and specifications
I plan to create a separate section for these type of documents, but I wanted to get this online for now. I purchased the Samsung (made by SEMA, the division split off of Samsung that mostly makes floppy drives) SFD...
correctly reading an entire track reliably from PC drive
OK Great news. As I stumbled on in the last post: I’ve fixed my reading issues, and I’m now reliably reading, in one shot, an entire amiga track from the unmodified standard PC drive!! When seeing double...
current read problems
It seems as though when I have a read problem, its normally minor, and is a single bit error. I notice that the errors have a tendency for 0s to be incorrectly interpreted as 1s. So I get AB instead of 2B, AB instead of...
interesting results
OK, I’ve applied the “double 1’s” fix that I talked about earlier today. This definitely helped things. I think my results are quite possibly the best I’ve seen them yet. Now, my SX...
SX problem is double-ones, ISR code & description
While I shouldn’t be surprised, my SX hardware issue is related to double one’s, where the SX sees transitions back to back, and writes back to back 1’s into memory. This is assuming there aren’t...
