232 lines
10 KiB
Plaintext
232 lines
10 KiB
Plaintext
The comp.sys.apple2 Usenet newsgroup Apple II FAQs originate from
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the II Computing Apple II site, 1997-2012.
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Csa2 FAQs resource file: R032MMAP128.TXT
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128K Apple IIe Memory Map
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Note: To correctly view tables and diagrams on a super-res display,
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use a mono-spaced Font such as CoPilot or PCMononspaced.
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____________________________
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128K Apple IIe Memory Map
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by David Empson
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MAIN RAM AUX RAM I/O ROM
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______________ ______________
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0000 |Main zero page| |Aux zero page |
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|______________| |______________|
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0100 | Main stack | | Aux stack |
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|______________| |______________|
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0200 | | | |
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0300 | | | |
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|______________| |______________|
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0400 | | | |
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| Main text/GR | | Aux text/GR |
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| page 1 | | page 1X |
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|______________| |______________|
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0800 | | | |
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| Main text/GR | | Aux text/GR |
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| page 2 | | page 2X |
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|______________| |______________|
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0C00 | | | |
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... ...
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|______________| |______________|
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2000 | | | |
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| Main Hi-res | | Aux Hi-res |
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| page 1 | | page 1X |
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|______________| |______________|
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4000 | | | |
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| Main Hi-res | | Aux Hi-res |
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| page 2 | | page 2X |
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|______________| |______________|
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6000 | | | |
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... ...
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BFFF |______________| |______________| _____________
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C000 | Motherboard |
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| I/O |
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|_____________|
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C090 | Slot I/O |
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| (DEVSEL) |
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|_____________| _____________
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C100 | | | |
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| Slot CX ROM | | Int CX ROM |
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| (IOSEL) | | |
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|_____________| |_____________|
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C300 | Slot C3 ROM | | Int C3 ROM |
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| (IOSEL) | | |
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|_____________| |_____________|
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C400 | | | |
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| Slot CX ROM | | Int CX ROM |
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| (IOSEL) | | |
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|_____________| |_____________|
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C800 | | | |
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| Slot ROM | | |
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| (IOSTROBE) | | Int C3 ROM |
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| shared | | |
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| between | | |
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| slots | | |
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CFFF ______ ______ ______ ______ |_____________| |_____________|
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D000 | || | | || | | |
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| Main || Main | | Aux || Aux | | |
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| LC || LC | | LC || LC | | |
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| bank || bank | | bank || bank | | |
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| 1 || 2 | | 1 || 2 | | Applesoft |
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|______||______| |______||______| | |
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E000 | | | | | BASIC |
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| | | | | ROM |
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| Main | | Aux | | |
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| Language | | Language | | |
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| Card | | Card | | |
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| | | | |.............|
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F800 | | | | | Monitor |
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FFFF |______________| |______________| |_____________|
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(If you have a RAMWorks or similar bank-switched card in the auxiliary
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slot, then any 64K bank on the card can be switched into the auxiliary
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memory space. "Normal" auxiliary memory, which contains the video
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buffers, is bank 0 on the card.)
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The major soft-switches for bank switching control areas as follows:
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AUXZP/MAINZP selects main or auxiliary RAM in 0000-01FF (zero page and
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stack), and in D000-FFFF (language card), for read/write access. The
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language card area is further affected by language card soft-switches
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(see later).
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RDMAIN/RDAUX selects main or auxiliary RAM in 0200-BFFF for read access
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only. Text page 1/1X and Hi-res page 1/1X may be excluded depending on
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the state of the 80STORE and HIRES soft-switches.
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WRMAIN/WRAUX selects main or auxiliary RAM in 0200-BFFF for write access
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only. Text page 1/1X and Hi-res page 1/1X may be excluded depending on
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the state of the 80STORE and HIRES soft-switches.
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80STORE enables 80-column switching of text/lo-res page 1 (0400-07FF).
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The active page (main or auxiliary) is determined by the PAGE1/PAGE2
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soft switch. 80STORE gives read/write access to whichever page is
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active.
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If 80STORE and HIRES are both enabled, then PAGE1/PAGE2 also control
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switching of hi-res page 1 (2000-3FFF).
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There is no special bank switching support for text or hi-res page 2/2X.
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Using the double resolution modes with these pages requires using
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another bank switching technique.
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SLOTCXROM/INTCXROM determines whether the slot address space or
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motherboard ROM is enabled for $C100-$C2FF and $C400-$C7FF.
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SLOTC3ROM/INTC3ROM determines whether the slot address space or
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motherboard ROM is enabled for $C300-$C3FF.
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The $C800-$CFFF area (I/O Stobe) is shared between all slots, and may be
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used by the internal ROM if INTC3ROM is active. An access to the
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$CN00-$CNFF page (N=1 to 7) enables the expansion ROM space for slot N,
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if supported by that card. An access to $CFFF disables the expansion
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ROM space for all cards.
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There are eight language card soft-switches to control selection of RAM
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bank 1 or 2, read enable for RAM or ROM, and write enable for RAM.
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Handy stub routines to access the auxiliary language card area are as
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follows:
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RDAUX1 SEI ; No interrupts!
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LDX C088 ; Read-enable language card bank 1
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STA C009 ; Switch in auxiliary language card, etc.
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LDA xxxx ; Read target location (patched)
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STA C008 ; Switch in main language card, etc.
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LDX C08A ; Switch the ROM back in
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CLI ; Enable interrupts
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RTS
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WRAUX1 SEI ; No interrupts!
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LDX C08B ; Read/write language card bank 1
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LDX C08B ; (must access twice)
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STA C009 ; Switch in auxiliary language card, etc.
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STA xxxx ; Write target location (patched)
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STA C008 ; Switch in main language card, etc.
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LDX C08A ; Switch the ROM back in
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CLI ; Enable interrupts
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RTS
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RDAUX2 SEI ; No interrupts!
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LDX C080 ; Read-enable language card bank 2
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STA C009 ; Switch in auxiliary language card, etc.
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LDA xxxx ; Read target location (patched)
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STA C008 ; Switch in main language card, etc.
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LDX C082 ; Switch the ROM back in
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CLI ; Enable interrupts
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RTS
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WRAUX2 SEI ; No interrupts!
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LDX C083 ; Read/write language card bank 2
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LDX C083 ; (must access twice)
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STA C009 ; Switch in auxiliary language card, etc.
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STA xxxx ; Write target location (patched)
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STA C008 ; Switch in main language card, etc.
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LDX C082 ; Switch the ROM back in
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CLI ; Enable interrupts
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RTS
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The C008/C009 switch controls both read and write access, unlike the
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switches for the main $0200-$BFFF area, but note the different
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instruction sequences needed to control read enable and read/write
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enable for the language card area. (You could set up the language card
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for write-only access using C081 or C089 instead of C083 or C08B, but it
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won't make the code any shorter.)
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