Ampro Corporation 486E - Manual (Page 65)

Product Reference
2–49
Addressing the Byte-wide Socket
Use SETUP to specify the size and starting address of the byte-wide socket, and whether the BIOS
enables the socket upon system initialization. Table 2–36 lists the possible settings for sizes and
address ranges of the byte-wide socket.
Note
When the byte-wide socket is enabled, the memory address space it
uses is unavailable for other devices, even if no memory device is
installed in the socket. You must disable the byte-wide socket in
SETUP before you can use the memory space for other purposes.
Table 2–36. Window Size and Address Selection
Window Address
DISABLE N/A
64K D0000-DFFFFh
64K E0000-EFFFFh
128K D0000-EFFFFh
A device used in the byte-wide socket must have access times of 250 nS or less.
If you install a device that is smaller than the selected window size, the contents of the device are
duplicated in the byte-wide socket’s memory space. For example, the software sees two copies of a
32K device in a 64K window, and 4 copies in a 128K window.
A16 is inverted so 128K devices programmed off board will have the halves swapped, for example,
the lower half will be in the E0000 segment.
ROM-BIOS Extensions
The system can be configured to run its application from the byte-wide socket instead of loading it
from a disk drive. This technique, known as a ROM BIOS extension, directly executes the
application during the Power-On Self Test (POST) instead of booting from floppy or hard disk. For
additional information regarding the ROM-BIOS extension concept and its practical
implementation, contact Ampro Technical Support.