The century register is only present in "recent" version of the chip,
and is at an address corresponding to the NVRAM memory. It is not
manipulated directly by the RTC and therefore is always in BCD format.
The current QEMU implementation is correct.
** Changed in: qemu
Status: New => Invalid
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https://bugs.launchpad.net/bugs/659276
Title:
Accessing Century byte via RTC
Status in QEMU:
Invalid
Bug description:
With the RTC configure for Binary instead of BCD I am getting the
incorrect result for Century.
mov al, 0x0B ; Set RTC to binary mode
out 0x70, al
in al, 0x71
bts ax, 2
mov bl, al
mov al, 0x0B
out 0x70, al
mov al, bl
out 0x71, al
mov al, 0x32 ; Century
out 0x70, al
in al, 0x71
In QEMU 0.12.5 it returns 0x20 but should return 0x14. The following
work correctly:
mov al, 0x09 ; Year
out 0x70, al
in al, 0x71
mov al, 0x08 ; Month
out 0x70, al
in al, 0x71
mov al, 0x07 ; Day
out 0x70, al
in al, 0x71
