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Inverted the operation of the OPTi 495 A20 control bit and made the AT keyboard controller (8042) as well as memory default to A20 off - makes both the MR 386 DX and the Award 386 and 486 clones work correctly;

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The Amstrad MegaPC now correctly initializes the internal Paradise WD90C11 graphics card, making the machine work again.
This commit is contained in:
OBattler
2018-01-04 01:57:55 +01:00
parent 412ae3726b
commit 9b2705eb9f
4 changed files with 14 additions and 13 deletions
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10
src/mem.c
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@@ -1358,12 +1358,12 @@ void mem_add_bios()
}
int mem_a20_key = 0, mem_a20_alt = 0;
int mem_a20_state = 1;
int mem_a20_state = 0;
void mem_a20_init(void)
{
if (AT) {
rammask = cpu_16bitbus ? 0xffffff : 0xffffffff;
rammask = cpu_16bitbus ? 0xefffff : 0xffefffff;
flushmmucache();
mem_a20_state = mem_a20_key | mem_a20_alt;
} else {
@@ -1461,8 +1461,6 @@ void mem_init(void)
mem_mapping_add(&ram_split_mapping, mem_size * 1024, 384 * 1024, mem_read_ram, mem_read_ramw, mem_read_raml, mem_write_ram, mem_write_ramw, mem_write_raml, ram + (1 << 20), MEM_MAPPING_INTERNAL, NULL);
mem_mapping_disable(&ram_split_mapping);
mem_a20_key = 2;
mem_a20_alt = 0;
mem_a20_init();
}
@@ -1635,8 +1633,6 @@ void mem_resize()
mem_mapping_add(&ram_split_mapping, mem_size * 1024, 384 * 1024, mem_read_ram, mem_read_ramw, mem_read_raml, mem_write_ram, mem_write_ramw, mem_write_raml, ram + (1 << 20), MEM_MAPPING_INTERNAL, NULL);
mem_mapping_disable(&ram_split_mapping);
mem_a20_key = 2;
mem_a20_alt = 0;
mem_a20_init();
}
@@ -1691,7 +1687,7 @@ static void port_92_write(uint16_t port, uint8_t val, void *priv)
{
if ((mem_a20_alt ^ val) & 2)
{
mem_a20_alt = val & 2;
mem_a20_alt = (val & 2) ? 0 : 2;
mem_a20_recalc();
}