Fast Gate A20 - American Megatrends Baby EISA User Manual

ADVANCED CMOS SETUP Options,
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External Cache Memory
This option enables secondary (or external) cache memory. The settings are Enabled or Disabled. The
BIOS Setup default is Enabled. The Power-On default is Disabled.
Internal Cache Memory
This option enables the 8 KB cache memory in the Intel 80486 microprocessor. The settings are Enabled or
Disabled. The BIOS Setup default is Enabled. The Power-On default is Disabled.
Fast Gate A20 Option
Gate A20 controls the ability to access memory addresses above 1 MB by enabling or disabling access to
the processor address line A20. To remain XT-compatible and be able to access conventional memory
(from 0 - 1024K), address line A20 must always be low, so Gate A20 must be disabled. However, some
software programs both enter protected mode and use the CMOS RAM Shutdown byte to return to real
mode via the BIOS. For this software, Gate A20 must be constantly enabled and disabled via the keyboard
controller, which is slow. The settings are Enabled or Disabled. Fast Gate A20 is an alternate method of
enabling Gate A20 that permits faster switching between addresses modes. The BIOS Setup default is
Enabled. The Power-On default is Disabled.
Turbo Switch Function
The settings are Enabled or Disabled. This option enables the hardware turbo switch, which permits the
user to change system speeds. The BIOS Setup and Power-On default is Enabled.
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American Megatrends 80486 Baby EISA Motherboard User's Guide