Subject: Re: [stella] Zero-Page Memory Addressing.. (Still a newbie, but getting there.) From: Manuel Polik <cybergoth@xxxxxxxx> Date: Fri, 02 Nov 2001 14:05:21 +0100 |
HiJoel! >to me now... Absolute Addressing is 1 click slower right? Depending on what you're doing, in most cases: yes! >My question is about Zero-Page Addressing. Any thing in zero-page is >accessed with single bytes, that's easy. But where is this Zero-Page stuff >located?? It is, as the name indicates the first page, i.e. the bytes from $00 to $FF (or from $0000 to $00FF to be more precise) > Is it allready built into the Atari somewhere, instead of on the >cart?? Yup! > What is the size of the Zero-Page I've seen variables > defined > usually set in the &80 range.. The zero page is splitted in two equal parts. The first from $00 - $7F is where the TIA registers are located. (Check out VCS.H to find out where is which.) The second half is the famous 128 byte RAM. As you already found out, it's ranging from $80 - $FF. So all RAM access is actually in the zeropage, which means there's very fast access here. (Any serious C64 coder would sell his grandma for 128 Bytes free zeropage RAM, BTW :-)) >Thanks, HTH > I'm sorry again if this is a total repeat. Uhm, well... :-) Greetings, Manuel ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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