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ABit AB-BX6: Force bit 4 of CMOS register 39h to 1, fixes intermittent POST freezes on POST code AAh on later BIOS revisions.

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OBattler
2025-12-19 22:30:28 +01:00
parent 56a631e95a
commit a99577d2eb
1 changed files with 15 additions and 0 deletions
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15
src/nvr_at.c
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@@ -635,6 +635,13 @@ nvr_reg_write(uint16_t reg, uint8_t val, void *priv)
nvr_reg_common_write(reg, val, nvr, local);
break;
case 0x39:
if (machines[machine].init == machine_at_bx6_init)
nvr_reg_common_write(reg, val | 0x08, nvr, local);
else
nvr_reg_common_write(reg, val, nvr, local);
break;
default: /* non-RTC registers are just NVRAM */
nvr_reg_common_write(reg, val, nvr, local);
break;
@@ -794,6 +801,14 @@ nvr_read(uint16_t addr, void *priv)
ret = nvr->regs[local->addr[addr_id]];
break;
case 0x39:
if (!(local->lock[local->addr[addr_id]] & 0x02)) {
ret = nvr->regs[local->addr[addr_id]];
if (machines[machine].init == machine_at_bx6_init)
ret |= 0x08;
}
break;
case 0x3e:
case 0x3f:
if (!nvr->is_new && (local->flags & FLAG_AMI_1995_HACK)) {