nesdev.com

facepalm.. sorry man, I just accidentally mangled your post. thought I was editing mine. I need to go to bed.

edit: OK, I hit the back button to recover it and hopefully have restored it

I must have made a typo in my previous test; with my kinda ugly memory dumper, I only ever see the same 512-byte pattern regardless of what all the higher address lines do.

Two different SST39SF040s have the same bytes at offsets $3B-$3D, so maybe that's a lot code (since it differs from Memblers's)

I wonder if those varying bytes are a date? 0E0C04 could be 2014-December-4 and 0F0601 could be 2015-June-1 ... The datecode on my two (with 0E0C04) is 1446, 46th week of 2014, or mid-November...

I just had a chance to check the date, and it is 1522 on that chip. June 1st was the first day of 23rd week, that's about the right time. That's kinda cool to be able to read that in the software.