Subject: Re: [stella] Nick's PlayField Graphics Demo: Question From: "Roger Williams" <mer02@xxxxxxxxxxxxx> Date: Thu, 11 Jul 2002 21:09:23 -0700 |
From: Roagie <roagie@xxxxxxx> > Is there a memory map of the 2600? RAM is 128 bytes from $80 through $FF, and is mirrored from $180 through $1FF which is convenient since the stack lives in the $1XX page, and this way the stack can share RAM which otherwise is entirely in page 0. TIA registers are mapped from $0 through $3F. You get different ones depending on whether you read or write. PIA registers are mapped $280-$2FF. All this low-page stuff is repeated throughout the lower 4K of memory $0000-$0FFF. ROM is 4K from $1000 through $1FFF. You can call this $F000 through $FFFF if you prefer; it's all the same. The 6807 only has 13 external address lines so it is limited to 8K overall memory map; the 6802 instruction set sees this repeated to fill the 64K address space of the CPU instruction memory map. You need the "Stella Programmer's Guide," available on most fine Stella resource sites, to explain what the registers are (if a bit cryptically). --Roger Williams ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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