] ] [#FFFF] ] > It's accessed using MREQ# rather than IORQ#. ] > Are you saying you don't have ] > to select slot 3 in order to change it? ] ] Yes No.
The secundairy slot register is contained within the primary slot! With other words: If primary slot 2 is expanded with a secundairy slot register (at 0xffff), you need to select primary slot 2 into page 3 to modify that secundairy slot register. Likewise, if primary slot 3 is expanded with a secundairy slot register (again at 0xffff), you need to select primary slot 3 into page 3 to modify that secundairy slot register. Furthermore, modifications to secundairy slot register in primary slot 2 are invisible to modifications to secundairy slot register in primary slot 3. Etc. ] Reading #FFFF will return the *inverse* of what you've written into ] it (don't ask ;-)). This is indeed correct. Reason: you can detect the presence of a secundairy slot register by writing to address 0xffff, reading back the value and checking if it has become inversed. If yes, then a secundairy slot is present. This is used by the memory search routine of MSX in the ROM-Bios, which is executed as part of the reset routine. The result of this search is placed in system area, where it remains available for all other programs. Kind regards, Alex Wulms -- Visit The MSX Plaza (http://www.inter.nl.net/users/A.P.Wulms) for info on XelaSoft, Merlasoft, Quadrivium, SD-Snatcher on fMSX, the MSX Hardware list, XSA Disk images, documentation, Japanese MSX news from Ikeda and lots more. -- For info, see http://www.stack.nl/~wynke/MSX/listinfo.html
