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A20 problem
Posted: Wed Aug 31, 2005 12:30 am
by raywill
Sometimes in some tutorials they don't clear the keyboard buffer before the open A20 line.
Will it also do?
I tried so,and I can also run 32 code after merely "open A20" without clear the buffer.
But in bochs log file.CR0's first bit is 0,instead of 1.
---What's inside?
Re:A20 problem
Posted: Wed Aug 31, 2005 2:56 am
by Pype.Clicker
raywill wrote:
Sometimes in some tutorials they don't clear the keyboard buffer before the open A20 line.
Will it also do?
I guess it will depend on how long you've been disabling ints. Chances that the user hit a key on the 1?s period (1000 instructions on my CPU) between CLI and A20 enable are quite weak.
I tried so,and I can also run 32 code after merely "open A20" without clear the buffer.
But in bochs log file.CR0's first bit is 0,instead of 1.
hum. What are you exactly talking about, here ? CR0=1 only when you set it to 1 to enable protected mode. I don't see any direct relationship with A20 gate status ...
---What's inside?