techtravels.org

inital results on error correction

While I have yet to actually implement the full-scale error correction as I want to, I did some manual tests today. I basically took a track that I was erroring out on, and swapped in 1-bit away values for the bad bytes.  In some cases, it appeared...

Latest articles

Am I reading MFM wrong?

I’m beginning to think that I don’t fully understand the signalling coming out of the drive. I understand the concepts behind MFM (I think), but the actual application to this project, I’m not so sure...

more real world tests

So tonight, I put my new FPGA implementation of the amiga floppy project to good use.  I read some more of my collection of amiga floppies. GREAT NEWS. It’s working like a champ.  As a matter of fact, I selected...

further development on the AFP

I’m about to bring a new member of my family into this world.  As a new proud parent, I’m completely unsure about what this means in terms of time, dedication, and so on.  I’m sure I’ll have less...

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...

today’s successes

I really stumbled on some stuff, and I think I have traction on a couple of problems. 1. My sizes are absolutely perfect. For me, this is a big milestone. This tells me alot. I’m getting perfect distances between...

my checksum algorithm

So I’m using an XOR checksum to detect errors in the transfer between the SX and the PC.  I always thought it was a reasonably strong checksum, even though it’s still an 8 bit checksum. I found a neat...

March 21st Status

Well, here’s where I’m at: The external amiga floppy drive is now hooked directly to my SX microcontroller.  The code within the microcontroller waits for a command.  If it get’s a “B”...

good data vs bad

So you’ve seen me talk about good data and bad data.  But what’s the difference? Good data looks like the picture I posted awhile back here. Note the very even spread of 4—4—8.  Every pattern is...