On Thu, 22 Feb 2001 ncoplin@orbeng.com.au wrote: > I assume then that there was never an official CBM way to make the > expansion even though they design protected signal names? I don't quite understand what you mean. Should "they" be "their"? Anyway, I assume that the MMU chip internally generates the CAS signals for RAM banks 2 and 3, but for some reason they didn't want to manufacture a bigger chip so that these signals could be brought out from the chip. (I think that the MMU is 48 pins already.) The MMU registers do store the extra bits. On an unexpanded machine, selecting bank 2 is equivalent to selecting bank 0, and 3 is the same as 1. The .sfx (self-extracting lharchive) file header detects C64 or C128 mode by switching to bank 2, crashing an expanded machine. I don't know if other programs misuse this feature to detect the C128 mode. Marko - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail cbm-hackers-request@dot.tml.hut.fi.
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