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 the 16-bit memory address…….If it succeeds it writes, “MEM-OK” to the serial port, a “MEM-FAIL” is a pretty bad error and the program refuses to run.  No sense in continuing on if the memory is bad.

Quick dirty code, but it does the trick.  I can’t really cause a failure without screwing w/ the hardware…. I guess I could momentarily touch the data pin to ground or something that should cause it to read/write a misplaced 0…..

The more I test hardware for a living, the more test cases I can come up with to put this thing through its paces.

Last night, until 2:30am, I had my Amiga 500 hooked up to my logic analyzer.  Can’t figure out when Paula is dma’ing the 16-bit words to memory, I’ve got to look at clocks etc.  I think the DMAL pin should be pulsing at some point.  When I get more time to work on it, I’m going to take a look.  I’ve got to order more of those xgrabbers or whatever the heck they are called.  Mini probes basically….

More later………..


Amateur Electronics Design Engineer and Hacker