Flash Boot Device; Nonvolatile Sram Memory; Battery - RadiSys EPC - 6A Hardware Reference Manual

EPC-6A Hardware Reference
also contains Datalight ROM-DOS (version 6.22, revision 2.1) as a 250KB portion of the
memory space.
The intent of the flash memory is to hold application programs in a standard file-system
format, as opposed to being directly user accessible. Software drivers are provided with
the EPC-6A for this purpose.

Flash Boot Device

The 28F004BV-T contains two 8KB parameter blocks. Block 1 is used for System BIOS
code storage and is not available for application use.

Nonvolatile SRAM Memory

A 128K x 8 bit array of nonvolatile SRAM memory is provided. The software supports
only 32KB of SRAM. The SRAM address space is accessible through I/O registers where
8380h, 8381h, and 8382h control the address and 8384h provides data access.
The BIOS and ROM DOS use the upper 2 KB of the SRAM array to communicate error
messages to the setup program. Thus the user should consider the SRAM as a 30 KB array.
Information in the upper 2 KB of the SRAM memory runs the risk of getting destroyed by
the BIOS after a reset. Writing into the upper 2 KB of SRAM memory runs the risk of
destroying error messages saved for the setup program.

Battery

The battery powers the CMOS RAM and TOD clock when system power is not present.
At 60×C, the battery should have a shelf life of over four years. In a system that is
powered on much of the time and where the ambient power-off temperature is less than
60×C, the battery is estimated to have a life of 10 years.
The battery holder is for a 23 mm coin cell, such as a Panasonic BR2330 or
Rayovac BR2335.
To remove or replace the battery, first remove the EXM card guide above the battery by
removing its three mounting screws. The battery cell is held in place by a spring lever. To
remove the battery, apply downward pressure to the cell in the vicinity of the base of the
spring (a small screwdriver may be used), while at the same time applying lateral pressure
to the cell in the direction away from the spring base.
A new cell is installed by sliding it beneath the spring until it snaps into the holder. Ensure
that the spring has not been damaged and that it is in firm contact with, and applying
downward pressure on, the battery cell.
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