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Groups > comp.sys.apple2.programmer > #2144
| From | "Bill Garber" <willy46pa@comcast.net> |
|---|---|
| Newsgroups | comp.sys.apple2.programmer |
| References | <n7f0e9$rk9$1@dont-email.me> <k42dnVXYrq6cWAbLnZ2dnUU78cednZ2d@giganews.com> <1mh7pg0.352duj18oqn5sN%dempson@actrix.gen.nz> |
| Subject | Re: Understanding a little something about bank-switched RAM |
| Date | 2016-01-17 15:33 -0500 |
| Message-ID | <58KdnXf8lp35ZwbLnZ2dnUU78RGdnZ2d@giganews.com> (permalink) |
"David Empson" <dempson@actrix.gen.nz> wrote in message news:1mh7pg0.352duj18oqn5sN%dempson@actrix.gen.nz... > Bill Garber <willy46pa@comcast.net> wrote: > >> "ultramagnus_tcv" <mikew@thecomputervalet.com> wrote >> in message news:n7f0e9$rk9$1@dont-email.me... >> > Hey Folks, >> > >> > In my never ending question to learn things, I am >> > attempting to understand something about bank >> > switching. I've been reading Inside The Apple //e >> > (slowly) and have happened upon something in the >> > Memory Management chapter that I don't understand. >> > It has to do with what the book lists as "two 4K >> > regions of memory from $D000 to $DFFF." The map >> > on the same page shows what seems to me to be part >> > of the story. >> > What I think I understand is that the map doesn't >> > show the 2nd bank from $D000 to $DFFF. I've drawn >> > a map I think represents what the book is saying >> > but I'd like to know if I understand it all. I also >> > don't understand from the book's map which bank is >> > represented in the map. Is it Bank 1? Bank 2? Does >> > it matter when it comes to drawing this map. My >> > guess is it doesn't, but I'd like to know. I've >> > placed images of the pages I'm reading on Imgur in >> > a small album with portions underlined or otherwise. >> > Thanks to everyone for their replies. >> > http://imgur.com/a/P0NQL >> > $FFFF +------------------+ +------------------+ >> > | | | STANDARD | >> > | | | SYSTEM MONITOR | >> > $F800 | | +------------------+ >> > | | | | >> > | | | | >> > | | | | >> > | | | | >> > | | | APPLESOFT | >> > | | | INTERPRETER | >> > | | | | >> > +- - - - - - - - - -+ $E000 +------------------+ | | >> > | | | | | | >> > | THERE ARE TWO | | | >> > | BANK 2 | | $Dx BANKS | | | >> > | BANK 1 | | | >> > | | | | | | >> > +- - - - - - - - - -+ $D000 +------------------+ +------------------+ >> > INTERNAL INTERNAL ROM >> > BANK-SWITCHED >> > RAM >> >> Good job on the Memory Map. I couldn't have done >> any better than David or Michael explaining things. >> >> Many of us have abandoned the Apple II and II+ in >> lieu of the IIe, //e, and IIgs, since the latter >> models have everything they have without having >> to add all of the extra cards first. My only wish >> is that they'd have added the disk drive controller. > > In the //e, I assume you mean. It is built in for > the //c and IIgs. Yes David, thank you. I tend to forget that because I rarely use them in the //c and IIgs anymore. I use the SPVHD on my //cPlus, and CFFA3000 and Superdrives on the IIgs. Occasionally, I will activate the Disk- Port on the IIgs, but that is so rare, so very rare. >> Anyway, $D000-$FFFF Bank 1 is the built in ROMs, >> and Bank 2 is what is put on the language card. >> Very simple explanation, but it's what I know. > > That's not a notation I've ever heard. Ignoring auxiliary memory, the > memory in this area is either "ROM", "RAM bank 1" or "RAM bank 2", with > the RAM banks sometimes described as "bank-switched RAM" (ambiguous as > there are lots of bank-switched RAM sections in the //e and later), or > my preferred "language card" (which is not ambiguous, though technically > it isn't a "card" in the //e and later). > > Language card banks 1 and 2 have the same memory in $E000-$FFFF, but > different memory in $D000-$DFFF. > > This modification of the diagram may be clearer: > > $FFFF +------------------------------------+ +------------------+ > | | | STANDARD | > | THERE IS ONE | | SYSTEM MONITOR | > $F800 | $Ex AND $Fx | +------------------+ > | BANK, WHICH | | | > | IS THE SAME | | | > | WHETHER BANK 1 | | | > | OR BANK 2 | | | > | IS SELECTED | | APPLESOFT | > | | | INTERPRETER | > | | | | > $E000 +- - - - - - - - -++- - - - - - - - -+ | | > | || | | | > | THERE ARE TWO || THERE ARE TWO | | | > | $Dx BANKS || $Dx BANKS | | | > | BANK 2 || BANK 1 | | | > | || | | | > $D000 +-----------------++-----------------+ +------------------+ > INTERNAL INTERNAL ROM > BANK-SWITCHED > RAM > > -- > David Empson > dempson@actrix.gen.nz Thank you once again, David. I see that I need to go back and review some of this information. Bill Garber * http://www.sepa-electronics.com *
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Understanding a little something about bank-switched RAM ultramagnus_tcv <mikew@thecomputervalet.com> - 2016-01-16 21:08 -0600
Re: Understanding a little something about bank-switched RAM dempson@actrix.gen.nz (David Empson) - 2016-01-17 18:54 +1300
Re: Understanding a little something about bank-switched RAM ultramagnus_tcv <mikew@thecomputervalet.com> - 2016-01-17 11:38 -0600
Re: Understanding a little something about bank-switched RAM ultramagnus_tcv <mikew@thecomputervalet.com> - 2016-01-17 11:39 -0600
Re: Understanding a little something about bank-switched RAM dempson@actrix.gen.nz (David Empson) - 2016-01-18 09:07 +1300
Re: Understanding a little something about bank-switched RAM ultramagnus_tcv <mikew@thecomputervalet.com> - 2016-01-17 16:18 -0600
Re: Understanding a little something about bank-switched RAM dempson@actrix.gen.nz (David Empson) - 2016-01-18 15:42 +1300
Re: Understanding a little something about bank-switched RAM "Bill Garber" <willy46pa@comcast.net> - 2016-01-17 22:27 -0500
Re: Understanding a little something about bank-switched RAM ultramagnus_tcv <mikew@thecomputervalet.com> - 2016-01-18 10:53 -0600
Re: Understanding a little something about bank-switched RAM ultramagnus_tcv <mikew@thecomputervalet.com> - 2016-01-18 10:50 -0600
Re: Understanding a little something about bank-switched RAM michael.pohoreski@gmail.com - 2016-01-18 09:40 -0800
Re: Understanding a little something about bank-switched RAM ultramagnus_tcv <mikew@thecomputervalet.com> - 2016-01-18 17:23 -0600
Re: Understanding a little something about bank-switched RAM michael.pohoreski@gmail.com - 2016-01-19 23:05 -0800
Re: Understanding a little something about bank-switched RAM ultramagnus_tcv <mikew@thecomputervalet.com> - 2016-01-20 10:06 -0600
Re: Understanding a little something about bank-switched RAM michael.pohoreski@gmail.com - 2016-01-17 05:09 -0800
Re: Understanding a little something about bank-switched RAM ultramagnus_tcv <mikew@thecomputervalet.com> - 2016-01-17 18:36 -0600
Re: Understanding a little something about bank-switched RAM "Bill Garber" <willy46pa@comcast.net> - 2016-01-17 11:45 -0500
Re: Understanding a little something about bank-switched RAM dempson@actrix.gen.nz (David Empson) - 2016-01-18 09:07 +1300
Re: Understanding a little something about bank-switched RAM "Bill Garber" <willy46pa@comcast.net> - 2016-01-17 15:33 -0500
Re: Understanding a little something about bank-switched RAM michael.pohoreski@gmail.com - 2016-01-18 09:30 -0800
Re: Understanding a little something about bank-switched RAM dempson@actrix.gen.nz (David Empson) - 2016-01-20 18:17 +1300
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