Subject: Re: [stella] Parker Brother's E0 Bankswitching From: Adam Wozniak <adam@xxxxxxxxxxxxxxxx> Date: Fri, 25 Apr 2003 09:13:17 -0700 (PDT) |
On Fri, 25 Apr 2003, Joe Grand wrote: > The cartridge would need to know which slices are mapped to which segment > at any given point in time, since it will send back different code to the > system depending on which slice is actually mapped into the segment, right? > This sounds complicated to me from a cartridge point-of-view, especially if > you think in 1982 terms, since there will need to be some state machine > circuitry or something to keep track of the state of each segment (so > probably 9 bits of storage, 3 bits to specify the current slice 0-7 for > each segment). 9 bits is a lot if you're using 74xx series chips, but not if you're manufacturing custom RAM chips in high volume. Nowadays it'd be easy to do this in a CPLD. > Maybe another way to ask this is: When programming, once a slice is mapped > into a segment (with LDA to one of the hot-spots, LDA $1FE0 for example), > that memory map will stay the same until another slice is later loaded into > the segment (LDA $1FE1, for example). > > Am I understanding this properly? Yes. -- adam@xxxxxxxxxxxxxxxx http://cuddlepuddle.org/~adam/pgp.html Will code for food. http://cuddlepuddle.org/~adam/resume.html "Fools despise wisdom and instruction." Proverbs 1:7 ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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