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aiie/apple/applemmu.cpp

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#ifdef TEENSYDUINO
#include <Arduino.h>
#else
#include <stdio.h>
#include <unistd.h>
#endif
#include "applemmu.h"
#include "applemmu-rom.h"
#include "physicalspeaker.h"
#include "cpu.h"
#include "globals.h"
// apple //e memory map
/*
page 0x00: zero page (straight ram)
page 0x01: stack (straight ram)
page 0x02:
page 0x03:
text/lores page 1: 0x0400 - 0x7FF
text/lores page 2: 0x0800 - 0xBFF
pages 0x0C - 0x1F: straight ram
hires page 1: pages 0x20 - 0x3F
hires page 2: pages 0x40 - 0x5F
pages 0x60 - 0xBF: straight ram
page 0xc0: I/O switches
pages 0xc1 - 0xcf: slot ROMs
pages 0xd0 - 0xdf: Basic ROM
pages 0xe0 - 0xff: monitor ROM
*/
AppleMMU::AppleMMU(AppleDisplay *display)
{
anyKeyDown = false;
keyboardStrobe = 0x00;
isOpenApplePressed = false;
isClosedApplePressed = false;
for (int8_t i=0; i<=7; i++) {
slots[i] = NULL;
}
allocateMemory();
this->display = display;
this->display->setSwitches(&switches);
resetRAM(); // initialize RAM, load ROM
}
AppleMMU::~AppleMMU()
{
delete display;
// FIXME: clean up the memory we allocated
}
void AppleMMU::Reset()
{
resetRAM();
resetDisplay(); // sets the switches properly
}
uint8_t AppleMMU::read(uint16_t address)
{
if (address >= 0xC000 &&
address <= 0xC0FF) {
return readSwitches(address);
}
// If C800-CFFF isn't latched to a slot ROM, and we try to
// access a slot's memory space from C100-C7FF, then we need
// to latch in the slot's ROM.
if (slotLatch == -1 && address >= 0xc100 && address <= 0xc7ff) {
slotLatch = (address >> 8) & 0x07;
if (slotLatch == 3 && slot3rom) {
// Back off: UTA2E p. 5-28: don't latch in slot 3 ROM while
// the slot3rom flag is enabled
// fixme
slotLatch = 3;
} else {
updateMemoryPages();
}
}
// If we access CFFF, that unlatches slot ROM.
if (address == 0xCFFF) {
slotLatch = -1;
updateMemoryPages();
}
uint8_t res = readPages[address >> 8][address & 0xFF];
return res;
}
// Bypass MMU and read directly from a given page - also bypasses switches
uint8_t AppleMMU::readDirect(uint16_t address, uint8_t fromPage)
{
return ramPages[address >> 8][fromPage][address & 0xFF];
}
void AppleMMU::write(uint16_t address, uint8_t v)
{
if (address >= 0xC000 &&
address <= 0xC0FF) {
return writeSwitches(address, v);
}
// Don't allow writes to ROM
// Hard ROM, I/O, slots, whatnot
if (address >= 0xC100 && address <= 0xCFFF)
return;
// Bank-switched ROM/RAM areas
if (address >= 0xD000 && address <= 0xFFFF && !writebsr) {
return;
}
writePages[address >> 8][address & 0xFF] = v;
if (address >= 0x400 &&
address <= 0x7FF) {
// If it's text mode, or mixed mode, or lores graphics mode, then update.
if ((switches & S_TEXT) || (switches & S_MIXED) || (!(switches & S_HIRES))) {
// Force a redraw
display->modeChange();
}
return;
}
if (address >= 0x2000 &&
address <= 0x5FFF) {
if (switches & S_HIRES) {
// Force a redraw
display->modeChange();
}
}
}
// FIXME: this is no longer "MMU", is it?
void AppleMMU::resetDisplay()
{
updateMemoryPages();
display->modeChange();
}
void AppleMMU::handleMemorySwitches(uint16_t address, uint16_t lastSwitch)
{
// many of these are spelled out here:
// http://apple2.org.za/gswv/a2zine/faqs/csa2pfaq.html
switch (address) {
// These are write-only and perform no action on read
case 0xC000: // CLR80STORE
switches &= ~S_80STORE;
break;
case 0xC001: // SET80STORE
switches |= S_80STORE;
break;
case 0xC002: // CLRAUXRD read from main 48k RAM
auxRamRead = false;
break;
case 0xC003: // SETAUXRD read from aux/alt 48k
auxRamRead = true;
break;
case 0xC004: // CLRAUXWR write to main 48k RAM
auxRamWrite = false;
break;
case 0xC005: // SETAUXWR write to aux/alt 48k
auxRamWrite = true;
break;
case 0xC006: // CLRCXROM use ROM on cards
intcxrom = false;
break;
case 0xC007: // SETCXROM use internal ROM
intcxrom = true;
break;
case 0xC008: // CLRAUXZP use main zero page, stack, LC
altzp = false;
break;
case 0xC009: // SETAUXZP use alt zero page, stack, LC
altzp = true;
break;
case 0xC00A: // CLRC3ROM use internal slot 3 ROM
slot3rom = false;
break;
case 0xC00B: // SETC3ROM use external slot 3 ROM
slot3rom = true;
break;
// Registers C080 - C08F control bank switching.
case 0xC080:
case 0xC081:
case 0xC082:
case 0xC083:
case 0xC084:
case 0xC085:
case 0xC086:
case 0xC087:
case 0xC088:
case 0xC089:
case 0xC08A:
case 0xC08B:
case 0xC08C:
case 0xC08D:
case 0xC08E:
case 0xC08F:
// Per ITA2E, p. 286:
// (address & 0x08) controls whether or not we are selecting from bank2. Per table 8-2,
// bank2 is active if address & 0x08 is zero. So if the bit is on, it's bank 1.
bank2 = (address & 0x08) ? false : true;
// (address & 0x04) is unused.
// (address & 0x02) is read-select: if it is set the same as
// (address & 0x01) then readbsr is true.
readbsr = ((address & 0x02) >> 1) == (address & 0x01);
// (address & 0x01) is write-select: if 1, we write BSR RAM; if 0, we write ROM.
// But it's a little more complicated than readbsr.
// Per UTA2E p. 5-23:
// "Writing to high RAM is enabled when the HRAMWRT' soft switch
// is reset. ... It is reset by even read access or any write
// access in the $C08X range. HRAMWRT' is reset by odd read
// access in the $C08X range when PRE-WRITE is set. It is set by
// even access in the CC08X range. Any other type of access
// causes HRAMWRT' to hold its current state."
if (address & 0x01) {
if (preWriteFlag)
writebsr = 1;
// Per UTA2E, p. 5-23: any other preWriteFlag leaves writebsr unchanged.
} else {
writebsr = false;
}
break;
}
updateMemoryPages();
}
// many (most? all?) switches are documented here:
// http://apple2.org.za/gswv/a2zine/faqs/csa2pfaq.html
uint8_t AppleMMU::readSwitches(uint16_t address)
{
static uint16_t lastReadSwitch = 0x0000;
static uint16_t thisReadSwitch = 0x0000;
lastReadSwitch = thisReadSwitch;
thisReadSwitch = address;
// If this is a read for any of the slot switches, and we have
// hardware in that slot, then return its result.
if (address >= 0xC090 && address <= 0xC0FF) {
for (uint8_t i=1; i<=7; i++) {
if (address >= (0xC080 | (i << 4)) &&
address <= (0xC08F | (i << 4))) {
if (slots[i]) {
return slots[i]->readSwitches(address & ~(0xC080 | (i<<4)));
}
else
return FLOATING;
}
}
}
switch (address) {
case 0xC010:
// consume the keyboard strobe flag
keyboardStrobe &= 0x7F;
return (anyKeyDown ? 0x80 : 0x00);
case 0xC080:
case 0xC081:
case 0xC082:
case 0xC083:
case 0xC084:
case 0xC085:
case 0xC086:
case 0xC087:
case 0xC088:
case 0xC089:
case 0xC08A:
case 0xC08B:
case 0xC08C:
case 0xC08D:
case 0xC08E:
case 0xC08F:
// but read does affect these, same as write
handleMemorySwitches(address, lastReadSwitch);
// UTA2E, p. 5-23: preWrite is set by odd read access, and reset
// by even read access
preWriteFlag = (address & 0x01);
break;
case 0xC00C: // CLR80VID disable 80-col video mode
if (switches & S_80COL) {
switches &= ~S_80COL;
resetDisplay();
}
break;
case 0xC00D: // SET80VID enable 80-col video mode
if (!(switches & S_80COL)) {
switches |= S_80COL;
resetDisplay();
}
break;
case 0xC00E: // CLRALTCH use main char set - norm LC, flash UC
switches &= ~S_ALTCH;
break;
case 0xC00F: // SETALTCH use alt char set - norm inverse, LC; no flash
switches |= S_ALTCH;
break;
case 0xC011: // RDLCBNK2
return bank2 ? 0x80 : 0x00;
case 0xC012: // RDLCRAM
return readbsr ? 0x80 : 0x00;
case 0xC013: // RDRAMRD
return auxRamRead ? 0x80 : 0x00;
case 0xC014: // RDRAMWR
return auxRamWrite ? 0x80 : 0x00;
case 0xC015: // RDCXROM
return intcxrom ? 0x80 : 0x00;
case 0xC016: // RDAUXZP
return altzp ? 0x80 : 0x00;
case 0xC017: // RDC3ROM
return slot3rom ? 0x80 : 0x00;
case 0xC018: // RD80COL
return (switches & S_80STORE) ? 0x80 : 0x00;
case 0xC019: // RDVBLBAR -- vertical blanking, for 4550 cycles of every 17030
// Should return 0 for 4550 of 17030 cycles. Since we're not really
// running full speed video, instead, I'm returning 0 for 4096 (2^12)
// of every 16384 (2^14) cycles; the math is easier.
if ((g_cpu->cycles & 0x3000) == 0x3000) {
return 0x00;
} else {
return 0xFF; // FIXME: is 0xFF correct? Or 0x80?
}
case 0xC01A: // RDTEXT
return ( (switches & S_TEXT) ? 0x80 : 0x00 );
case 0xC01B: // RDMIXED
return ( (switches & S_MIXED) ? 0x80 : 0x00 );
case 0xC01C: // RDPAGE2
return ( (switches & S_PAGE2) ? 0x80 : 0x00 );
case 0xC01D: // RDHIRES
return ( (switches & S_HIRES) ? 0x80 : 0x00 );
case 0xC01E: // RDALTCH
return ( (switches & S_ALTCH) ? 0x80 : 0x00 );
case 0xC01F: // RD80VID
return ( (switches & S_80COL) ? 0x80 : 0x00 );
case 0xC030: // SPEAKER
g_speaker->toggle();
break;
case 0xC050: // CLRTEXT
if (switches & S_TEXT) {
switches &= ~S_TEXT;
resetDisplay();
}
return FLOATING;
case 0xC051: // SETTEXT
if (!(switches & S_TEXT)) {
switches |= S_TEXT;
resetDisplay();
}
return FLOATING;
case 0xC052: // CLRMIXED
if (switches & S_MIXED) {
switches &= ~S_MIXED;
resetDisplay();
}
return FLOATING;
case 0xC053: // SETMIXED
if (!(switches & S_MIXED)) {
switches |= S_MIXED;
resetDisplay();
}
return FLOATING;
case 0xC054: // PAGE1
if (switches & S_PAGE2) {
switches &= ~S_PAGE2;
if (!(switches & S_80COL)) {
resetDisplay();
} else {
updateMemoryPages();
}
}
return FLOATING;
case 0xC055: // PAGE2
if (!(switches & S_PAGE2)) {
switches |= S_PAGE2;
if (!(switches & S_80COL)) {
resetDisplay();
} else {
updateMemoryPages();
}
}
return FLOATING;
case 0xC056: // CLRHIRES
if (switches & S_HIRES) {
switches &= ~S_HIRES;
resetDisplay();
}
return FLOATING;
case 0xC057: // SETHIRES
if (!(switches & S_HIRES)) {
switches |= S_HIRES;
resetDisplay();
}
return FLOATING;
case 0xC05E: // DHIRES ON
if (!(switches & S_DHIRES)) {
switches |= S_DHIRES;
resetDisplay();
}
return FLOATING;
case 0xC05F: // DHIRES OFF
if (switches & S_DHIRES) {
switches &= ~S_DHIRES;
resetDisplay();
}
return FLOATING;
// paddles
case 0xC061: // OPNAPPLE
return isOpenApplePressed ? 0x80 : 0x00;
case 0xC062: // CLSAPPLE
return isClosedApplePressed ? 0x80 : 0x00;
case 0xC070: // PDLTRIG
// It doesn't matter if we update readPages or writePages, because 0xC0
// has only one page.
readPages[0xC0][0x64] = readPages[0xC0][0x65] = 0xFF;
g_paddles->startReading();
return FLOATING;
}
if (address >= 0xc000 && address <= 0xc00f) {
// This is the keyboardStrobe support referenced in the switch statement above.
return keyboardStrobe;
}
return readPages[address >> 8][address & 0xFF];
}
void AppleMMU::writeSwitches(uint16_t address, uint8_t v)
{
// fixme: combine these with the last read switch
static uint16_t lastWriteSwitch = 0x0000;
static uint16_t thisWriteSwitch = 0x0000;
lastWriteSwitch = thisWriteSwitch;
thisWriteSwitch = address;
// If this is a write for any of the slot switches, and we have
// hardware in that slot, then return its result.
if (address >= 0xC090 && address <= 0xC0FF) {
for (uint8_t i=1; i<=7; i++) {
if (address >= (0xC080 | (i << 4)) &&
address <= (0xC08F | (i << 4))) {
if (slots[i]) {
slots[i]->writeSwitches(address & ~(0xC080 | (i<<4)), v);
return;
}
}
}
}
switch (address) {
case 0xC010:
case 0xC011: // Per Understanding the Apple //e, p. 7-3:
case 0xC012: // a write to any $C01x address causes
case 0xC013: // a clear of the keyboard strobe.
case 0xC014:
case 0xC015:
case 0xC016:
case 0xC017:
case 0xC018:
case 0xC019:
case 0xC01A:
case 0xC01B:
case 0xC01C:
case 0xC01D:
case 0xC01E:
case 0xC01F:
keyboardStrobe &= 0x7F;
return;
case 0xC050: // graphics mode
if (switches & S_TEXT) {
switches &= ~S_TEXT;
resetDisplay();
}
return;
case 0xC051:
if (!(switches & S_TEXT)) {
switches |= S_TEXT;
resetDisplay();
}
return;
case 0xC052: // "no mixed"
if (switches & S_MIXED) {
switches &= ~S_MIXED;
resetDisplay();
}
return;
case 0xC053: // "mixed"
if (!(switches & S_MIXED)) {
switches |= S_MIXED;
resetDisplay();
}
return;
case 0xC054: // page2 off
if (switches & S_PAGE2) {
switches &= ~S_PAGE2;
if (!(switches & S_80COL)) {
resetDisplay();
} else {
updateMemoryPages();
}
}
return;
case 0xC055: // page2 on
if (!(switches & S_PAGE2)) {
switches |= S_PAGE2;
if (!(switches & S_80COL)) {
resetDisplay();
} else {
updateMemoryPages();
}
}
return;
case 0xC056: // hires off
if (switches & S_HIRES) {
switches &= ~S_HIRES;
resetDisplay();
}
return;
case 0xC057: // hires on
if (!(switches & S_HIRES)) {
switches |= S_HIRES;
resetDisplay();
}
return;
case 0xC05E: // DHIRES ON
if (!(switches & S_DHIRES)) {
switches |= S_DHIRES;
resetDisplay();
}
return;
case 0xC05F: // DHIRES OFF
if (switches & S_DHIRES) {
switches &= ~S_DHIRES;
resetDisplay();
}
return;
// paddles
case 0xC070:
g_paddles->startReading();
writePages[0xC0][0x64] = writePages[0xC0][0x65] = 0xFF;
break;
case 0xC080:
case 0xC081:
case 0xC082:
case 0xC083:
case 0xC084:
case 0xC085:
case 0xC086:
case 0xC087:
case 0xC088:
case 0xC089:
case 0xC08A:
case 0xC08B:
case 0xC08C:
case 0xC08D:
case 0xC08E:
case 0xC08F:
// UTA2E, p. 5-23: preWrite is reset by any write access to these
preWriteFlag = 0;
// fall through...
case 0xC000:
case 0xC001:
case 0xC002:
case 0xC003:
case 0xC004:
case 0xC005:
case 0xC006:
case 0xC007:
case 0xC008:
case 0xC009:
case 0xC00A:
case 0xC00B:
handleMemorySwitches(address, lastWriteSwitch);
break;
case 0xC00C: // CLR80VID disable 80-col video mode
if (switches & S_80COL) {
switches &= ~S_80COL;
resetDisplay();
}
break;
case 0xC00D: // SET80VID enable 80-col video mode
if (!(switches & S_80COL)) {
switches |= S_80COL;
resetDisplay();
}
break;
case 0xC00E: // CLRALTCH use main char set - norm LC, flash UC
switches &= ~S_ALTCH;
break;
case 0xC00F: // SETALTCH use alt char set - norm inverse, LC; no flash
switches |= S_ALTCH;
break;
}
}
void AppleMMU::keyboardInput(uint8_t v)
{
keyboardStrobe = v | 0x80;
anyKeyDown = true;
}
void AppleMMU::setKeyDown(bool isTrue)
{
anyKeyDown = isTrue;
}
void AppleMMU::triggerPaddleTimer(uint8_t paddle)
{
writePages[0xC0][0x64 + paddle] = 0x00;
}
void AppleMMU::resetRAM()
{
switches = S_TEXT;
// Per UTA2E, p. 5-23:
// When a system reset occurs, all MMU soft switches are reset (turned off).
bank2 = false;
auxRamRead = auxRamWrite = false;
readbsr = writebsr = false;
altzp = false;
intcxrom = false;
slot3rom = false;
slotLatch = -1;
preWriteFlag = false;
// Clear all the pages
for (uint8_t i=0; i<0xFF; i++) {
for (uint8_t j=0; j<5; j++) {
if (ramPages[i][j]) {
for (uint16_t k=0; k<0x100; k++) {
ramPages[i][j][k] = 0;
}
}
}
// and set our expectation of what we're reading from/writing to
readPages[i] = writePages[i] = ramPages[i][0];
}
// Load system ROM
for (uint16_t i=0x80; i<=0xFF; i++) {
for (uint16_t k=0; k<0x100; k++) {
uint16_t idx = ((i-0x80) << 8) | k;
#ifdef TEENSYDUINO
uint8_t v = pgm_read_byte(&romData[idx]);
#else
uint8_t v = romData[idx];
#endif
for (int j=0; j<5; j++) {
// For the ROM section from 0xc100 .. 0xcfff, we load in to
// an alternate page space (INTCXROM).
if (i >= 0xc1 && i <= 0xcf) {
// If we want to convince the VM we've got 128k of RAM, we
// need to load C3 ROM in page 0 (but not 1, meaning there's
// a board installed); and C800.CFFF in both page [0] and [1]
// (meaning there's an extended 80-column ROM available,
// that is also physically in the slot).
// Everything else goes in page [1].
if (i == 0xc3)
ramPages[i][0][k] = v;
else if (i >= 0xc8)
ramPages[i][0][k] = ramPages[i][1][k] = v;
else
ramPages[i][1][k] = v;
} else {
// Everything else goes in page 0.
ramPages[i][0][k] = v;
}
}
}
}
// have each slot load its ROM
for (uint8_t slotnum = 0; slotnum <= 7; slotnum++) {
if (slots[slotnum]) {
slots[slotnum]->loadROM(ramPages[0xC0 + slotnum][0]);
}
}
// update the memory read/write flags &c. Not strictly necessary, if
// we're really setting all the RAM flags to the right default
// settings above - but better safe than sorry?
updateMemoryPages();
}
void AppleMMU::setSlot(int8_t slotnum, Slot *peripheral)
{
slots[slotnum] = peripheral;
if (slots[slotnum]) {
slots[slotnum]->loadROM(ramPages[0xC0 + slotnum][0]);
}
}
void AppleMMU::allocateMemory()
{
for (uint16_t i=0; i<0xC0; i++) {
for (uint8_t j=0; j<2; j++) {
ramPages[i][j] = (uint8_t *)malloc(0x100);
}
for (uint8_t j=2; j<5; j++) {
ramPages[i][j] = NULL;
}
readPages[i] = ramPages[i][0];
writePages[i] = ramPages[i][0];
}
for (uint16_t i=0xC0; i<0x100; i++) {
for (uint8_t j=0; j<5; j++) {
ramPages[i][j] = (uint8_t *)malloc(0x100);
}
readPages[i] = ramPages[i][0];
writePages[i] = ramPages[i][0];
}
}
void AppleMMU::updateMemoryPages()
{
if (auxRamRead) {
for (uint8_t idx = 0x02; idx < 0xc0; idx++) {
readPages[idx] = ramPages[idx][1];
}
} else {
for (uint8_t idx = 0x02; idx < 0xc0; idx++) {
readPages[idx] = ramPages[idx][0];
}
}
if (auxRamWrite) {
for (uint8_t idx = 0x02; idx < 0xc0; idx++) {
writePages[idx] = ramPages[idx][1];
}
} else {
for (uint8_t idx = 0x02; idx < 0xc0; idx++) {
writePages[idx] = ramPages[idx][0];
}
}
if (switches & S_80STORE) {
// When S_80STORE is on, we switch 400-800 and 2000-4000 based on S_PAGE2.
// The behavior is different based on whether HIRESON/OFF is set.
if (switches & S_PAGE2) {
// Regardless of HIRESON/OFF, pages 0x400-0x7ff are switched on S_PAGE2
for (uint8_t idx = 0x04; idx < 0x08; idx++) {
readPages[idx] = ramPages[idx][1];
writePages[idx] = ramPages[idx][1];
}
// but 2000-3fff switches based on S_PAGE2 only if HIRES is on.
// HIRESOFF: 400-7ff doesn't switch based on read/write flags
// b/c it switches based on S_PAGE2 instead
// HIRESON: 400-800, 2000-3fff doesn't switch
// b/c they switch based on S_PAGE2 instead
// If HIRES is on, then we honor the PAGE2 setting; otherwise, we don't
for (uint8_t idx = 0x20; idx < 0x40; idx++) {
readPages[idx] = ramPages[idx][(switches & S_HIRES) ? 1 : 0];
writePages[idx] = ramPages[idx][(switches & S_HIRES) ? 1 : 0];
}
} else {
for (uint8_t idx = 0x04; idx < 0x08; idx++) {
readPages[idx] = ramPages[idx][0];
writePages[idx] = ramPages[idx][0];
}
for (uint8_t idx = 0x20; idx < 0x40; idx++) {
readPages[idx] = ramPages[idx][0];
writePages[idx] = ramPages[idx][0];
}
}
}
if (intcxrom) {
for (uint8_t idx = 0xc1; idx < 0xd0; idx++) {
readPages[idx] = ramPages[idx][1];
}
} else {
for (uint8_t idx = 0xc1; idx < 0xd0; idx++) {
readPages[idx] = ramPages[idx][0];
}
if (slot3rom) {
readPages[0xc3] = ramPages[0xc3][1];
for (int i=0xc8; i<=0xcf; i++) {
readPages[i] = ramPages[i][1];
}
}
}
// If slotLatch is set (!= -1), then we are mapping 2k of ROM
// for a given peripheral to C800..CFFF.
if (slotLatch != -1) {
// FIXME: the only peripheral we support this with right now is
// the 80-column card.
if (slotLatch == 3) {
for (int i=0xc8; i <= 0xcf; i++) {
readPages[i] = ramPages[i][1];
}
}
}
// set zero-page & stack pages based on altzp flag
if (altzp) {
for (uint8_t idx = 0x00; idx < 0x02; idx++) {
readPages[idx] = ramPages[idx][1];
writePages[idx] = ramPages[idx][1];
}
} else {
for (uint8_t idx = 0x00; idx < 0x02; idx++) {
readPages[idx] = ramPages[idx][0];
writePages[idx] = ramPages[idx][0];
}
}
// Set bank-switched ram reading from readbsr & bank2
if (readbsr) {
// 0xD0 - 0xE0 has 4 possible banks:
if (!bank2) {
// Bank 1 RAM: either in main RAM (1) or in the extended memory
// card (3):
for (uint8_t idx = 0xd0; idx < 0xe0; idx++) {
readPages[idx] = ramPages[idx][altzp ? 3 : 1];
}
} else {
// Bank 2 RAM: either in main RAM (2) or in the extended memory
// card (4):
for (uint8_t idx = 0xd0; idx < 0xe0; idx++) {
readPages[idx] = ramPages[idx][altzp ? 4 : 2];
}
}
// ... but 0xE0 - 0xFF has just the motherboard RAM (1) and
// extended memory card RAM (2):
for (uint16_t idx = 0xe0; idx < 0x100; idx++) {
readPages[idx] = ramPages[idx][altzp ? 2 : 1];
}
} else {
// Built-in ROM
for (uint16_t idx = 0xd0; idx < 0x100; idx++) {
readPages[idx] = ramPages[idx][0];
}
}
if (writebsr) {
if (!bank2) {
for (uint8_t idx = 0xd0; idx < 0xe0; idx++) {
writePages[idx] = ramPages[idx][altzp ? 3 : 1];
}
} else {
for (uint8_t idx = 0xd0; idx < 0xe0; idx++) {
writePages[idx] = ramPages[idx][altzp ? 4 : 2];
}
}
for (uint16_t idx = 0xe0; idx < 0x100; idx++) {
writePages[idx] = ramPages[idx][altzp ? 2 : 1];
}
} else {
for (uint16_t idx = 0xd0; idx < 0x100; idx++) {
writePages[idx] = ramPages[idx][0];
}
}
}
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