Subject: Re: [stella] new bankswitching scheme ? From: "Kroko" <Nil.Krokodil@xxxxxxx> Date: Mon, 2 Feb 2004 23:33:49 +0100 |
> Try this: > > Think of the SRAM as 128 blocks each of 1024 bytes. > Let 3F control the first 2K of the cart's addressable space: > > Writing a value N with the MSB cleared (i.e. from 0 to 127) there maps > blocks N and N+1 into the first 2K, read only (i.e. as if it were ROM). > > Writing a value N with the MSB set (i.e. from 128 to 255) there maps > block N as RAM, with the first 1K as read and the second 1K as write. > > Let 3E control the second 2K in a similar manner: > > Writing a value N with the MSB cleared (i.e. from 0 to 127) there maps > blocks N and N+1 into the second 2K, read only (i.e. as if it were ROM). > > Writing a value N with the MSB set (i.e. from 128 to 255) there maps > block N as RAM, with the third 1K as read and the fourth 1K as write. > > Did that make sense? Now any part of the 128K SRAM can be mapped as > RAM or ROM. Hey that does also sound intersting. There is 512K flash-ROM AND 128K of SRAM. I would like to be compatible with Andrews 3F stuff because the babies are so funny :-)) What I would like to do is simply enhance and existing BS scheme such that it is possible to map in the 128K of RAM in addition to the 512K ROM. I like the idea to enhance 3F because its so easy to select banks. Just write a number to a memory location. And then it is usable like superchip, FA or CV .... a read port and a write port.. -Kroko ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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