The comp.sys.apple2 Usenet newsgroup Apple II FAQs originate from the Ground Apple II archive. Administrator: Steve Nelson Csa2 FAQs-on-Ground resource file: R032MMAP128.TXT 128K Apple IIe Memory Map Note: To correctly view tables and diagrams on a super-res display, use a mono-spaced Font such as CoPilot or PCMononspaced. ____________________________ 128K Apple IIe Memory Map by David Empson MAIN RAM AUX RAM I/O ROM ______________ ______________ 0000 |Main zero page| |Aux zero page | |______________| |______________| 0100 | Main stack | | Aux stack | |______________| |______________| 0200 | | | | | | | | 0300 | | | | |______________| |______________| 0400 | | | | | | | | | Main text/GR | | Aux text/GR | | | | | | page 1 | | page 1X | | | | | | | | | |______________| |______________| 0800 | | | | | | | | | Main text/GR | | Aux text/GR | | | | | | page 2 | | page 2X | | | | | | | | | |______________| |______________| 0C00 | | | | | | | | ... ... | | | | |______________| |______________| 2000 | | | | | | | | | Main Hi-res | | Aux Hi-res | | | | | | page 1 | | page 1X | | | | | | | | | |______________| |______________| 4000 | | | | | | | | | Main Hi-res | | Aux Hi-res | | | | | | page 2 | | page 2X | | | | | | | | | |______________| |______________| 6000 | | | | | | | | | | | | ... ... | | | | | | | | BFFF |______________| |______________| _____________ C000 | Motherboard | | I/O | |_____________| C090 | Slot I/O | | (DEVSEL) | |_____________| _____________ C100 | | | | | Slot CX ROM | | Int CX ROM | | (IOSEL) | | | | | | | |_____________| |_____________| C300 | Slot C3 ROM | | Int C3 ROM | | (IOSEL) | | | |_____________| |_____________| C400 | | | | | | | | | Slot CX ROM | | Int CX ROM | | (IOSEL) | | | | | | | | | | | | | | | |_____________| |_____________| C800 | | | | | Slot ROM | | | | (IOSTROBE) | | Int C3 ROM | | | | | | shared | | | | between | | | | slots | | | CFFF ______ ______ ______ ______ |_____________| |_____________| D000 | || | | || | | | | Main || Main | | Aux || Aux | | | | || | | || | | | | LC || LC | | LC || LC | | | | || | | || | | | | bank || bank | | bank || bank | | | | 1 || 2 | | 1 || 2 | | Applesoft | |______||______| |______||______| | | E000 | | | | | BASIC | | | | | | | | | | | | ROM | | | | | | | | | | | | | | Main | | Aux | | | | | | | | | | Language | | Language | | | | | | | | | | Card | | Card | | | | | | | | | | | | | |.............| F800 | | | | | Monitor | | | | | | | | | | | | ROM | FFFF |______________| |______________| |_____________| (If you have a RAMWorks or similar bank-switched card in the auxiliary slot, then any 64K bank on the card can be switched into the auxiliary memory space. "Normal" auxiliary memory, which contains the video buffers, is bank 0 on the card.) The major soft-switches for bank switching control areas as follows: AUXZP/MAINZP selects main or auxiliary RAM in 0000-01FF (zero page and stack), and in D000-FFFF (language card), for read/write access. The language card area is further affected by language card soft-switches (see later). RDMAIN/RDAUX selects main or auxiliary RAM in 0200-BFFF for read access only. Text page 1/1X and Hi-res page 1/1X may be excluded depending on the state of the 80STORE and HIRES soft-switches. WRMAIN/WRAUX selects main or auxiliary RAM in 0200-BFFF for write access only. Text page 1/1X and Hi-res page 1/1X may be excluded depending on the state of the 80STORE and HIRES soft-switches. 80STORE enables 80-column switching of text/lo-res page 1 (0400-07FF). The active page (main or auxiliary) is determined by the PAGE1/PAGE2 soft switch. 80STORE gives read/write access to whichever page is active. If 80STORE and HIRES are both enabled, then PAGE1/PAGE2 also control switching of hi-res page 1 (2000-3FFF). There is no special bank switching support for text or hi-res page 2/2X. Using the double resolution modes with these pages requires using another bank switching technique. SLOTCXROM/INTCXROM determines whether the slot address space or motherboard ROM is enabled for $C100-$C2FF and $C400-$C7FF. SLOTC3ROM/INTC3ROM determines whether the slot address space or motherboard ROM is enabled for $C300-$C3FF. The $C800-$CFFF area (I/O Stobe) is shared between all slots, and may be used by the internal ROM if INTC3ROM is active. An access to the $CN00-$CNFF page (N=1 to 7) enables the expansion ROM space for slot N, if supported by that card. An access to $CFFF disables the expansion ROM space for all cards. There are eight language card soft-switches to control selection of RAM bank 1 or 2, read enable for RAM or ROM, and write enable for RAM. Handy stub routines to access the auxiliary language card area are as follows: RDAUX1 SEI ; No interrupts! LDX C088 ; Read-enable language card bank 1 STA C009 ; Switch in auxiliary language card, etc. LDA xxxx ; Read target location (patched) STA C008 ; Switch in main language card, etc. LDX C08A ; Switch the ROM back in CLI ; Enable interrupts RTS WRAUX1 SEI ; No interrupts! LDX C08B ; Read/write language card bank 1 LDX C08B ; (must access twice) STA C009 ; Switch in auxiliary language card, etc. STA xxxx ; Write target location (patched) STA C008 ; Switch in main language card, etc. LDX C08A ; Switch the ROM back in CLI ; Enable interrupts RTS RDAUX2 SEI ; No interrupts! LDX C080 ; Read-enable language card bank 2 STA C009 ; Switch in auxiliary language card, etc. LDA xxxx ; Read target location (patched) STA C008 ; Switch in main language card, etc. LDX C082 ; Switch the ROM back in CLI ; Enable interrupts RTS WRAUX2 SEI ; No interrupts! ...
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