package izapple2 import "fmt" // See https://fabiensanglard.net/fd_proxy/prince_of_persia/Inside%20the%20Apple%20IIe.pdf // See https://i.stack.imgur.com/yn21s.gif type memoryManager struct { apple2 *Apple2 // Main RAM area: 0x0000 to 0xbfff physicalMainRAM *memoryRange // 0x0000 to 0xbfff, Up to 48 Kb // Slots area: 0xc000 to 0xcfff cardsROM [8]memoryHandler //0xcs00 to 0xcSff. 256 bytes for each card cardsROMExtra [8]memoryHandler // 0xc800 to 0xcfff. 2048 bytes for each card // Upper area ROM: 0xc000 to 0xffff (or 0xd000 to 0xffff on the II+) physicalROM [4]memoryHandler // 0xc000 (or 0xd000) to 0xffff, 16 (or 12) Kb. Up to four banks // Language card upper area RAM: 0xd000 to 0xffff. One bank for regular LC cards, up to 8 with Saturn physicalLangRAM []*memoryRange // 0xd000 to 0xffff, 12KB. Up to 8 banks. physicalLangAltRAM []*memoryRange // 0xd000 to 0xdfff, 4KB. Up to 8 banks. // Extended RAM: 0x0000 to 0xffff (with 4Kb moved from 0xc000 to 0xd000 alt). One bank for extended Apple 2e card, up to 256 with RamWorks physicalExtRAM []*memoryRange // 0x0000 to 0xffff. 60Kb, 0xc000 to 0xcfff not used. Up to 256 banks physicalExtAltRAM []*memoryRange // 0xd000 to 0xdfff, 4Kb. Up to 256 banks. // Configuration switches, Language cards lcSelectedBlock uint8 // Language card block selected. Usually, allways 0. But Saturn has 8 lcActiveRead bool // Upper RAM active for read lcActiveWrite bool // Upper RAM active for write lcAltBank bool // Alternate // Configuration switches, Apple //e altZeroPage bool // Use extra RAM from 0x0000 to 0x01ff. And additional language card block altMainRAMActiveRead bool // Use extra RAM from 0x0200 to 0xbfff for read altMainRAMActiveWrite bool // Use extra RAM from 0x0200 to 0xbfff for write store80Active bool // Special pagination for text and graphics areas slotC3ROMActive bool // Apple2e slot 3 ROM shadow intCxROMActive bool // Apple2e slots internal ROM shadow intC8ROMActive bool // C8Rom associated to the internal slot 3. Softswitch not directly accessible. See UtA2e 5-28 activeSlot uint8 // Active slot owner of 0xc800 to 0xcfff extendedRAMBlock uint8 // Block used for entended memory for RAMWorks cards // Configuration switches, Base64A romPage uint8 // Active ROM page // Resolution cache lastAddressPage uint16 // The first byte is the page. The second is zero when the cached is valid. lastAddressHandler memoryHandler } const ( ioC8Off uint16 = 0xcfff addressLimitZero uint16 = 0x01ff addressStartText uint16 = 0x0400 addressLimitText uint16 = 0x07ff addressStartHgr uint16 = 0x2000 addressLimitHgr uint16 = 0x3fff addressLimitMainRAM uint16 = 0xbfff addressLimitIO uint16 = 0xc0ff addressLimitSlots uint16 = 0xc7ff addressLimitSlotsExtra uint16 = 0xcfff addressLimitDArea uint16 = 0xdfff invalidAddressPage uint16 = 0x0001 ) type memoryHandler interface { peek(uint16) uint8 poke(uint16, uint8) setBase(uint16) } func newMemoryManager(a *Apple2) *memoryManager { var mmu memoryManager mmu.apple2 = a mmu.physicalMainRAM = newMemoryRange(0, make([]uint8, 0xc000), "Main RAM") mmu.slotC3ROMActive = true // For II+, this is the default behaviour return &mmu } func (mmu *memoryManager) accessCArea(address uint16) memoryHandler { slot := uint8((address >> 8) & 0x0f) // Internal IIe slot 3 if (address <= addressLimitSlots) && !mmu.slotC3ROMActive && (slot == 3) { mmu.intC8ROMActive = true return mmu.physicalROM[mmu.romPage] } // Internal IIe CxROM if mmu.intCxROMActive { return mmu.physicalROM[mmu.romPage] } // First slot area if slot <= 7 { mmu.activeSlot = slot mmu.intC8ROMActive = false return mmu.cardsROM[slot] } // Extra slot area reset if address == ioC8Off { // Reset extra slot area owner mmu.activeSlot = 0 mmu.intC8ROMActive = false } // Extra slot area if mmu.intC8ROMActive { return mmu.physicalROM[mmu.romPage] } return mmu.cardsROMExtra[mmu.activeSlot] } func (mmu *memoryManager) accessUpperRAMArea(address uint16) memoryHandler { if mmu.altZeroPage { // Use extended RAM block := mmu.extendedRAMBlock if mmu.lcAltBank && address <= addressLimitDArea { return mmu.physicalExtAltRAM[block] } return mmu.physicalExtRAM[mmu.extendedRAMBlock] } // Use language card block := mmu.lcSelectedBlock if mmu.lcAltBank && address <= addressLimitDArea { return mmu.physicalLangAltRAM[block] } return mmu.physicalLangRAM[block] } func (mmu *memoryManager) getPhysicalMainRAM(ext bool) memoryHandler { if ext { return mmu.physicalExtRAM[mmu.extendedRAMBlock] } return mmu.physicalMainRAM } func (mmu *memoryManager) getVideoRAM(ext bool) *memoryRange { if ext { // The video memory uses the first extended RAM block, even with RAMWorks return mmu.physicalExtRAM[0] } return mmu.physicalMainRAM } func (mmu *memoryManager) accessRead(address uint16) memoryHandler { if address <= addressLimitZero { return mmu.getPhysicalMainRAM(mmu.altZeroPage) } if mmu.store80Active && address <= addressLimitHgr { altPage := mmu.apple2.io.isSoftSwitchActive(ioFlagSecondPage) // TODO: move flag to mmu property like the store80 if address >= addressStartText && address <= addressLimitText { return mmu.getPhysicalMainRAM(altPage) } hires := mmu.apple2.io.isSoftSwitchActive(ioFlagHiRes) if hires && address >= addressStartHgr && address <= addressLimitHgr { return mmu.getPhysicalMainRAM(altPage) } } if address <= addressLimitMainRAM { return mmu.getPhysicalMainRAM(mmu.altMainRAMActiveRead) } if address <= addressLimitIO { mmu.lastAddressPage = invalidAddressPage return mmu.apple2.io } if address <= addressLimitSlotsExtra { return mmu.accessCArea(address) } if mmu.lcActiveRead { return mmu.accessUpperRAMArea(address) } return mmu.physicalROM[mmu.romPage] } func (mmu *memoryManager) accessWrite(address uint16) memoryHandler { if address <= addressLimitZero { return mmu.getPhysicalMainRAM(mmu.altZeroPage) } if address <= addressLimitHgr && mmu.store80Active { altPage := mmu.apple2.io.isSoftSwitchActive(ioFlagSecondPage) if address >= addressStartText && address <= addressLimitText { return mmu.getPhysicalMainRAM(altPage) } hires := mmu.apple2.io.isSoftSwitchActive(ioFlagHiRes) if hires && address >= addressStartHgr && address <= addressLimitHgr { return mmu.getPhysicalMainRAM(altPage) } } if address <= addressLimitMainRAM { return mmu.getPhysicalMainRAM(mmu.altMainRAMActiveWrite) } if address <= addressLimitIO { mmu.lastAddressPage = invalidAddressPage return mmu.apple2.io } if address <= addressLimitSlotsExtra { return mmu.accessCArea(address) } if mmu.lcActiveWrite { return mmu.accessUpperRAMArea(address) } return mmu.physicalROM[mmu.romPage] } // Peek returns the data on the given address func (mmu *memoryManager) Peek(address uint16) uint8 { mh := mmu.accessRead(address) if mh == nil { return 0xf4 // Or some random number } value := mh.peek(address) //if address >= 0xc400 && address < 0xc500 { // fmt.Printf("[MMU] Peek at %04x: %02x\n", address, value) //} return value } // Peek returns the data on the given address optimized for more local requests func (mmu *memoryManager) PeekCode(address uint16) uint8 { page := address & 0xff00 var mh memoryHandler if page == mmu.lastAddressPage { mh = mmu.lastAddressHandler } else { mh = mmu.accessRead(address) if address&0xf000 != 0xc000 { // Do not cache 0xC area as it may reconfigure the MMU mmu.lastAddressPage = page mmu.lastAddressHandler = mh } } if mh == nil { return 0xf4 // Or some random number } value := mh.peek(address) //if address >= 0xc400 && address < 0xc500 { // fmt.Printf("[MMU] PeekCode at %04x: %02x\n", address, value) //} return value } // Poke sets the data at the given address func (mmu *memoryManager) Poke(address uint16, value uint8) { mh := mmu.accessWrite(address) if mh != nil { mh.poke(address, value) } //if address >= 0x0036 && address <= 0x0039 { // fmt.Printf("[MMU] Poke at %04x: %02x\n", address, value) //} } // Memory initialization func (mmu *memoryManager) setCardROM(slot int, mh memoryHandler) { mmu.cardsROM[slot] = mh } func (mmu *memoryManager) setCardROMExtra(slot int, mh memoryHandler) { mmu.cardsROMExtra[slot] = mh } func (mmu *memoryManager) initLanguageRAM(groups uint8) { // Apple II+ language card or Saturn (up to 8 groups) mmu.physicalLangRAM = make([]*memoryRange, groups) mmu.physicalLangAltRAM = make([]*memoryRange, groups) for i := uint8(0); i < groups; i++ { mmu.physicalLangRAM[i] = newMemoryRange(0xd000, make([]uint8, 0x3000), fmt.Sprintf("LC RAM block %v", i)) mmu.physicalLangAltRAM[i] = newMemoryRange(0xd000, make([]uint8, 0x1000), fmt.Sprintf("LC RAM Alt block %v", i)) } } func (mmu *memoryManager) initExtendedRAM(groups int) { // Apple IIe 80 col card with 64Kb style RAM or RAMWorks (up to 256 banks) mmu.physicalExtRAM = make([]*memoryRange, groups) mmu.physicalExtAltRAM = make([]*memoryRange, groups) for i := 0; i < groups; i++ { mmu.physicalExtRAM[i] = newMemoryRange(0, make([]uint8, 0x10000), fmt.Sprintf("Extra RAM block %v", i)) mmu.physicalExtAltRAM[i] = newMemoryRange(0xd000, make([]uint8, 0x1000), fmt.Sprintf("Extra RAM Alt block %v", i)) } } // Memory configuration func (mmu *memoryManager) setActiveROMPage(page uint8) { mmu.romPage = page } func (mmu *memoryManager) getActiveROMPage() uint8 { return mmu.romPage } func (mmu *memoryManager) setLanguageRAM(readActive bool, writeActive bool, altBank bool) { mmu.lcActiveRead = readActive mmu.lcActiveWrite = writeActive mmu.lcAltBank = altBank } func (mmu *memoryManager) setLanguageRAMActiveBlock(block uint8) { block = block % uint8(len(mmu.physicalLangRAM)) mmu.lcSelectedBlock = block } func (mmu *memoryManager) setExtendedRAMActiveBlock(block uint8) { if int(block) >= len(mmu.physicalExtRAM) { // How does the real hardware reacts? block = 0 } mmu.extendedRAMBlock = block } func (mmu *memoryManager) reset() { if mmu.apple2.isApple2e { // MMU UtA2e 4-14, 5-22 mmu.altZeroPage = false mmu.altMainRAMActiveRead = false mmu.altMainRAMActiveWrite = false mmu.store80Active = false mmu.slotC3ROMActive = false mmu.intCxROMActive = false mmu.intC8ROMActive = false // IOU UtaA2e 7-3 // "All softswitches except KEYSTROKE, TEXT and MIXED are reset // when the RESET line drops low" mmu.apple2.io.softSwitchesData[ioFlagSecondPage] = ssOff mmu.apple2.io.softSwitchesData[ioFlagHiRes] = ssOff mmu.apple2.io.softSwitchesData[ioFlag80Col] = ssOff mmu.apple2.io.softSwitchesData[ioDataNewVideo] = ssOff // ioFlagText ? } }