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

new face of the amiga floppy project

You’d think that with the lack of posts lately that I haven’t been doing anything. BUT, in fact, I’ve been quite busy. I now have the entire floppy project on one single circuit board, the SX28...

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...

losing data

I’ve been thinking more and more about how exactly I’ve been losing data. It’s alot of data. The worst case I’ve seen is about 140 bytes. This is 1120 bits, or 2240us. This is a LONG time for my...

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...

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...

proof of concept works

Today is the first day in months that I’ve made what I consider good progress. I am now able to read any track(so far) off of any disk with 100% success including checking and relying on the checksums. I read...

first two bytes of checksum bad

Despite the data being received 100% correct, the data checksum fails in certain cases. It’s always the first two bytes of the 4-byte, 32-bit checksum that are wrong.  The last two are always right.  What does...