Subject: Re: [stella] FE bank switching again From: "Eric Ball" <ericball@xxxxxxxxxxxx> Date: Thu, 23 Jan 2003 21:31:32 -0500 |
The following (from http://www-2.cs.cmu.edu/~dsladic/vice/doc/64doc.txt) may help you figure out how FE works: RTS # address R/W description --- ------- --- ----------------------------------------------- 1 PC R fetch opcode, increment PC 2 PC R read next instruction byte (and throw it away) 3 $0100,S R increment S 4 $0100,S R pull PCL from stack, increment S 5 $0100,S R pull PCH from stack 6 PC R increment PC JSR # address R/W description --- ------- --- ------------------------------------------------- 1 PC R fetch opcode, increment PC 2 PC R fetch low address byte, increment PC 3 $0100,S R internal operation (predecrement S?) 4 $0100,S W push PCH on stack, decrement S 5 $0100,S W push PCL on stack, decrement S 6 PC R copy low address byte to PCL, fetch high address byte to PCH ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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