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

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. ...

Ground issues

Although I’ve been attempting to have a common ground for this whole project — I’m not sure that is going to happen. At least not at this stage of the game. I tried connecting the ground off the floppy...

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...

Creating more test disks

From both Tim’s suggestions and from a reinforcement from Agans’ Debugging book, Chapter 6, “Divide and Conquer”, they suggest to “Inject Easy-to-Spot Patterns”. And of course, I knew...

MFMSanityCheck

While I’m hesitant to post this at all, this is a quick and dirty application I threw together, and I do mean threw, that will check for valid MFM bytes. See the previous post for the link to the actual bytes. It...

updated code and comments

  Here’s a current version of the code.  I cleaned up my code tonight, added a bunch of comments, and tried to explain and document what I’m doing and the logic behind it. The current code is so much better...

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...

Parallel port access in win 2k

Accessing the parallel port directly under Windows 2000, XP, etc in a standard user app is not natively available, but there are a couple different solutions available. The free one I use is called WinIo, and it is...