diff options
| -rw-r--r-- | hw/misc/mac_via.c | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/hw/misc/mac_via.c b/hw/misc/mac_via.c index 3f473c3fcf..d8b35e6ca6 100644 --- a/hw/misc/mac_via.c +++ b/hw/misc/mac_via.c @@ -906,9 +906,24 @@ static uint64_t mos6522_q800_via2_read(void *opaque, hwaddr addr, unsigned size) { MOS6522Q800VIA2State *s = MOS6522_Q800_VIA2(opaque); MOS6522State *ms = MOS6522(s); + uint64_t val; addr = (addr >> 9) & 0xf; - return mos6522_read(ms, addr, size); + val = mos6522_read(ms, addr, size); + + switch (addr) { + case VIA_REG_IFR: + /* + * On a Q800 an emulated VIA2 is integrated into the onboard logic. The + * expectation of most OSs is that the DRQ bit is live, rather than + * latched as it would be on a real VIA so do the same here. + */ + val &= ~VIA2_IRQ_SCSI_DATA; + val |= (ms->last_irq_levels & VIA2_IRQ_SCSI_DATA); + break; + } + + return val; } static void mos6522_q800_via2_write(void *opaque, hwaddr addr, uint64_t val, |