ASPI2DOS.SYS and KEYB.COM from Win 98 SE installation CD (and most likely
other DOS versions too) depend on I/O port 0x61 bit 4 to be toggled. This
requires timer 1 (I/O 0x41, legacy DRAM refresh) to be correctly set.
Also Intel ICH7 Family Datasheet, chapter 5.8 states:
Programming the counter to anything other than Mode 2 will result in
undefined behavior for the REF_TOGGLE bit.
Failing to have the timer 1 configured indeed causes affected OSes to
freeze during the boot.
Signed-off-by: Petr Cvek <petrcve...@gmail.com>
---
src/hw/timer.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/src/hw/timer.c b/src/hw/timer.c
index b6f102e..b272f44 100644
--- a/src/hw/timer.c
+++ b/src/hw/timer.c
@@ -280,4 +280,10 @@ pit_setup(void)
// maximum count of 0000H = 18.2Hz
outb(0x0, PORT_PIT_COUNTER0);
outb(0x0, PORT_PIT_COUNTER0);
+
+ // timer1: binary count, 16bit count, mode 2
+ outb(PM_SEL_TIMER1|PM_ACCESS_WORD|PM_MODE2|PM_CNT_BINARY, PORT_PIT_MODE);
+ // maximum count of 0012H = 66.3kHz
+ outb(0x12, PORT_PIT_COUNTER1);
+ outb(0x0, PORT_PIT_COUNTER1);
}
--
2.37.0
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