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extended 80k card ROM handling fixups

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This commit is contained in:
Jorj Bauer 2017-03-03 09:00:41 -05:00
parent e033f6e039
commit b8e23bfa22
2 changed files with 55 additions and 1 deletions
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55
apple/applemmu.cpp
View File

@ -71,6 +71,27 @@ uint8_t AppleMMU::read(uint16_t address)
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();
}
// FIXME: assumes slot 4 is a mockingboard
if (slots[4] && address >= 0xC400 && address <= 0xC4FF) {
return ((Mockingboard *)slots[4])->read(address);
@ -658,6 +679,8 @@ void AppleMMU::resetRAM()
intcxrom = false;
slot3rom = false;
slotLatch = -1;
preWriteFlag = false;
// Clear all the pages
@ -685,8 +708,20 @@ void AppleMMU::resetRAM()
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) {
ramPages[i][1][k] = v;
// 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;
@ -801,6 +836,24 @@ void AppleMMU::updateMemoryPages()
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

1
apple/applemmu.h
View File

@ -72,6 +72,7 @@ class AppleMMU : public MMU {
bool altzp;
bool intcxrom;
bool slot3rom;
int8_t slotLatch;
bool preWriteFlag; // see UTA2E p. 5-23