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Old 15 January 2011, 14:28   #1618
Join Date: Jun 2010
Location: out in the wild
Posts: 1,251
Originally Posted by Ezrec View Post
Therefore, I need to implement the $8000000 SDRAM scanning myself.

Is there a specific method that I should use to determine the memory size of that region? Or should any 'generic' RAM size technique work?
"any generic" memory-scan routine may not be the best thing, as it may destroy memory contents. We went to great lengths to make memory contents survive any reset, so reset-proof software will also survive. If your memory test will alter memory contents, you might get undesired behaviour with your version of the kickstart rom.

Fortunately, the 68030 has lots of registers, so you can store contents of addresses that you're about to test with the usual test-values (such as 0x55/0xaa).

In order not to find any "phantom-memory", make sure to switch off data caches. Before reading back a value, you must read an address with known-different contents. Otherwise, you might end up reading a value from an open data bus, which may be stable for a few microseconds after your write - long enough to read back the value you're expecting. This would lead to false results.

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