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

recent status

Well, I’ve put a decent number of hours in on the project over the last couple weeks. I’ve mostly been “spinning my wheels” because I haven’t made much progress, but I think I’ve...

Schmitt Trigger

Welp, after talking with some smart guys on forums.parallax.com, it looks like the Schmitt Trigger feature on the SX is going to allow me to get rid of my 74HC132 that I’ve spent at least a couple hours messing...

logic analyzers

I’ve recently received a couple emails on additions to the logic analyzer page. Once I get some time to check them out, I’ll make the corrections. I’ve been super busy with life — switched jobs...

going around the problem

Welp, I’ve ordered a new, but cheap ($5.99!) regular PC floppy drive from newegg.com.  I like this end result much better anyways.  PC drives are much more available, popular, cheap, and so on. was worried about...

minor success at 2:00am

well I’ve got MFM flowing from the PC drive now.  A couple of things: Pins 10 and 14, the pins I’ve been using since last night, appear to be correct. Pin 10 is the motor lead.  Dropping a corresponding SX...

new design

I took David’s advice, and I rewrote the code last night. Some highlights: 1. ISR is entirely in assembly. Although I haven’t manually counted, it appears to be about 400ns in length. 2. ISR triggers only...

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...

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. ...