package izapple2 /* See: https://www.apple.asimov.net/documentation/hardware/machines/APPLE%20IIe%20Auxiliary%20Memory%20Softswitches.pdf */ const ( ioFlagAltChar uint8 = 0x1E ioFlag80Col uint8 = 0x1F ) const ( screenDrawCycles = uint64(12480 + 4550) screenVertBlankingCycles = uint64(4550) ) func addApple2ESoftSwitches(io *ioC0Page) { // New MMU read softswithes mmu := io.apple2.mmu addSoftSwitchesMmu(io, 0x02, 0x03, 0x13, &mmu.altMainRAMActiveRead, "RAMRD") addSoftSwitchesMmu(io, 0x04, 0x05, 0x14, &mmu.altMainRAMActiveWrite, "RAMWRT") addSoftSwitchesMmu(io, 0x06, 0x07, 0x15, &mmu.intCxROMActive, "INTCXROM") addSoftSwitchesMmu(io, 0x08, 0x09, 0x16, &mmu.altZeroPage, "ALTZP") addSoftSwitchesMmu(io, 0x0a, 0x0b, 0x17, &mmu.slotC3ROMActive, "SLOTC3ROM") mmu.slotC3ROMActive = false // Default behavior in II+ was true addSoftSwitchesMmu(io, 0x00, 0x01, 0x18, &mmu.store80Active, "80STORE") // New IOU read softswithes addSoftSwitchesIou(io, 0x0c, 0x0d, 0x1f, ioFlag80Col, "80COL") addSoftSwitchesIou(io, 0x0e, 0x0f, 0x1e, ioFlagAltChar, "ALTCHARSET") // Previous read softswithes io.addSoftSwitchR(0x1A, getStatusSoftSwitch(ioFlagText), "TEXT") io.addSoftSwitchR(0x1B, getStatusSoftSwitch(ioFlagMixed), "MIXED") io.addSoftSwitchR(0x1C, getStatusSoftSwitch(ioFlagSecondPage), "PAGE2") io.addSoftSwitchR(0x1D, getStatusSoftSwitch(ioFlagHiRes), "HIRES") io.addSoftSwitchR(0x11, func(_ *ioC0Page) uint8 { return ssFromBool(mmu.lcAltBank) }, "BSRBANK2") io.addSoftSwitchR(0x12, func(_ *ioC0Page) uint8 { return ssFromBool(mmu.lcActiveRead) }, "BSRREADRAM") io.addSoftSwitchR(0x19, func(_ *ioC0Page) uint8 { // See "Inside Apple IIe", page 268 // See http://rich12345.tripod.com/aiivideo/vbl.html // For each screen draw: // 12480 cycles drawing lines, VERTBLANK = $00 // 4550 cycles doing the return to position (0,0), VERTBLANK = $80 // Vert blank takes 12480 cycles every page redraw cycles := io.apple2.cpu.GetCycles() % screenDrawCycles if cycles <= screenVertBlankingCycles { return ssOn } return ssOff }, "VERTBLANK") //io.softSwitchesData[ioFlagAltChar] = ssOn // Not sure about this. } func addSoftSwitchesMmu(io *ioC0Page, addressClear uint8, addressSet uint8, AddressGet uint8, flag *bool, name string) { io.addSoftSwitchW(addressClear, func(_ *ioC0Page, _ uint8) { *flag = false }, name+"OFF") io.addSoftSwitchW(addressSet, func(_ *ioC0Page, _ uint8) { *flag = true }, name+"ON") io.addSoftSwitchR(AddressGet, func(_ *ioC0Page) uint8 { return ssFromBool(*flag) }, name) } func addSoftSwitchesIou(io *ioC0Page, addressClear uint8, addressSet uint8, AddressGet uint8, ioFlag uint8, name string) { io.addSoftSwitchW(addressClear, func(_ *ioC0Page, _ uint8) { io.softSwitchesData[ioFlag] = ssOff }, name+"OFF") io.addSoftSwitchW(addressSet, func(_ *ioC0Page, _ uint8) { io.softSwitchesData[ioFlag] = ssOn }, name+"ON") io.addSoftSwitchR(AddressGet, func(_ *ioC0Page) uint8 { return io.softSwitchesData[ioFlag] }, name) }