Marko, Todd may have more detailed information but in a nutshell ... The RAMLink combines the REU with any SIMMs installed to create one large virtual address space. A RAM disk partition is automatically created equal to the size of the REU. A second partition is automatically created equal to the size of any installed SIMMs. Because 24-bit addressing is used, the combined address space cannot exceed 16 MBytes. If more than 16 MB total RAM is installed, the entire REU will represent the first partition and SIMM RAM will represent the second partition up to 16 MB. Theoretically, if a 16 MB REU were installed then no SIMM RAM would be recognized by the system. The entire virtual address space would be taken up by the capacity of the REU. That is, assuming the RAMLink is capable of DETECTING an REU greater than 2 MB. It all comes down to the code used in the RAMLink initialization to detect the REU. --- Marko_Mäkelä <firstname.lastname@example.org> wrote: > Todd, > > > Sounds very good. I do ask for one thing, if it's > not too much trouble; > > Create a dipswitch arrangement where the user can > select from 1, 2, 4, 8 or > > 16Mb out of the 16Mb cartridge 'REU'. > > Hmm, why would you need that? The high-order bits > of the REU bank > selection register are normally unassigned, and the > 2 MB REU hack is > implemented in such a way that the added bank > selection bits cannot be > read by the processor. All memory in the REU sits > behind the controller, > and it can only be accessed by telling the > controller to copy data > between the C64 and the expansion memory. > > On the other hand, I don't know how the CMD RAMLink > works, since I have > never seen the device or its schematic diagram. ===== go6502 - Commodore and Apple II news, programs, hardware and resources http://www.geocities.com/profdredd __________________________________________________ Do You Yahoo!? Make international calls for as low as $.04/minute with Yahoo! Messenger http://phonecard.yahoo.com/ Message was sent through the cbm-hackers mailing list
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