XVI 16mhz mode and Geograph Seal crash

Started by trixster, March 29, 2020, 11:32:44 PM

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I have an XVI with 2MB PIO-6834-2/4M-1 ram board (jumpers set to 0 0 0 0) which works great in all respects except with Geograph Seal.

With the XVI set to 16Mhz I cannot get GS to run with switch.x set to 4096KB, either running from SCSI2SD or from floppy disks. I always get a Bus Error or Address Error once trying to start from the game menu.

If I set the machine to 10Mhz then the game plays fine either from scsi2sd or floppies with switch.x at 4096KB.

But if I set switch.x to 2048KB I can then successfully play the game at both 16 and 10Mhz.

So what is it about 16Mhz and my ram expansion that GS does not like?

I have run MTEST to confirm the memory on the PIO is fine, and in all other respects the machine operates great at 16Mhz....


Geograph is one of the very few games that takes full advantage of the XVI's faster internal RAM.  The i/o slots are slower.  You need to use the mobo's internal RAM expansion for geograph to function properly at 16mhz.  99% of the library does not care about the speed issue though.


Thanks for the info, that's interesting. I guess I'll need to check yahoo jp for an internal memory upgrade then.