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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

on memory controller optimization

So I’ve been trying to optimize a freeware memory controller for my particular memory chip. I’m running into this situation where the DRAM to ALTRAM copy takes upwards of 24us per line. But I only have a...

quick memory check

So on bootup, I now have the hardware do a memory check.  I basically take and write out a bunch of values to the memory, and then read them back and make sure they read back properly.  The values written are based on...

RXTX and Java

As I mentioned before, I’m using RXTX to do serial communication in Java since Sun has dropped support for serial communication under the Windows platform.  I want to revamp my read routines on the java side...

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...

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...

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...