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...

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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...

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...

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...

data rate vs throughput

Although I’m transmitting from the Parallax SX microcontroller to the PC via USB at a data rate of 2mbps, the actual throughput is much less.  First, there is some overhead, namely start and stop bits, which is...

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...

video showing current progress

I posted a video to youtube a little while ago showing my progress. It’s a little long winded (surprise surprise for those who read my posts) but it shows basically the framebuffer portion of the hardware working...

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...

of bit-shifted sectors

I’m beginning to think more and more that my software on the SX is just fine. Perhaps minus the idle routine mentioned in the last post. I have to do something there. However, without the idle routine, I was only...