Hi All, The SuperGames cartridge appears to be one of the very few "standard" Commodore cartridges which can directly use 27xxx EPROMS without adaptors. Here are the results of some trials I did on the weekend. U1 and U2 are 28pin ROMS capable of directly accepting 27x64, 27x128 or 27x256 EPROMS. 27x512 EPROMS may be possible if you add an extra 74175 latch. U1 is decoded to address space 8000-9FFF (ROML is CS) U2 is decoded to address space A000-BFFF (ROMH is CS) on reset, 74175 latch is reset, thus GAME/EXROM are both low mapping the 16cartridge ROM into memory, bank zero active. The 74175 latch is accessible for write only at DF00-DFFF, with the following bit definitions. Bits 0 & 1 define bank selection 0-3, 0 is power-on default. Bit 2 is GAME/EXROM control Bit 3 is like a "write protect" function preventing writes to the 74175 By setting Bit 2, RAM is available again 8000-9FFF and BASIC to A000-BFFF. A simple hack may be to re-wire Bit 3 as A15 for 27x512 capability or as individual control for GAME and EXROM for added memory mapping control. Does any one else have info other carts which take standard 27xxx ROMs? Enjoy, Nick ---------------------------------------------------------------------------------------------- PLEASE TAKE NOTE: The contents of this email (including any attachments) may be privileged and confidential. Any unauthorised use of the contents is expressly prohibited. If you have received this email in error, please advise us immediately (you can contact us by telephone on +61 8 9441 2311 by reverse charge) and then permanently delete this email together with any attachments. We appreciate your cooperation. Whilst Orbital endeavours to take reasonable care to ensure that this email and any attachments are free from viruses or other defects, Orbital does not represent or warrant that such are free from computer viruses or other defects. (C) 2000: Orbital Engine Company (Australia) Pty Ltd and its affiliates - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail cbm-hackers-request@dot.tcm.hut.fi.
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