butingting sa bios, nagresulta ng hang ng pc

subukan palitan yung A20 Fast to normal, maghahang yung pc, or matagal mag-boot. buti n lng marunong mag-reset ng cmos yung bro ko


history note:

A20 - a pain from the past: "A20 - a pain from the past
Everybody hates the CapsLock key, but keyboard manufacturers continue producing keyboards with CapsLock - it could be that someone wants it.

With A20 it is similar but worse. Really nobody wants it, but it continues to haunt us.

History
The 8088 in the original PC had only 20 address lines, good for 1 MB. The maximum address FFFF:FFFF addresses 0x10ffef, and this would silently wrap to 0x0ffef. When the 286 (with 24 address lines) was introduced, it had a real mode that was intended to be 100% compatible with the 8088. However, it failed to do this address truncation (a bug), and people found that there existed programs that actually depended on this truncation. Trying to achieve perfect compatibility, IBM invented a switch to enable/disable the 0x100000 address bit. Since the 8042 keyboard controller happened to have a spare pin, that was used to control the AND gate that disables this address bit. The signal is called A20, and if it is zero, bit 20 of all addresses is cleared."