Specifications

EPC-8A Hardware Reference

The BIOS initialization software copies the ROM contents into DRAM (a process called

shadowing) at addresses 0F0000–0FFFFF (also called the “F” page). The VGA BIOS is

copied into 0C0000–0C7FFF of DRAM. If the user has configured an EXM VGA card

(For example, an EXM-13A) and enabled it, the EXM’s BIOS is used for the copy.

Otherwise, the internal VGA BIOS is copied and enabled.

After copying into these areas, the BIOS write-protects them. Subsequent writes to these

areas complete successfully but do not alter the data in DRAM. However, the proper

sequence of writes alters data in the Flash boot device (BIOS ROM) itself, if the jumper

is installed.

There are two parameter blocks, each 8 Kbytes in size. Both blocks are used to store

BIOS code.

CMOS Backup and Restore

CMOS memory is backed up to and restored from Main Block 2 of the FBD as determined

by the settings in the BIOS Setup Exit Menu. This allows you to save your settings to

nonvolatile flash memory and to specify the conditions under which CMOS is to be

restored from the FBD. For more information, see the Exit Menu section of Chapter 3,

BIOS Configuration, on page 26.

Jumper JP2 (-BIOS) must be installed for Save to work. Be sure to remove the

jumper after using this function.

Video Controller

The EPC-8A hardware includes a VGA graphics controller implemented using the Chips

and Technologies 65545. This is connected to the CPU local bus to give the best possible

graphics performance. VGA memory is 512 Kbytes, resulting in the following resolutions:

Dimensions Resolution

640 x 480 16 or 256 colors

800 x 600 16 or 256 colors

1024 x 768 16 colors

Figure 4-2. Flash Boot Device Memory

FFFE0000 System BIOS

128 Kbytes

FFFC0000 Boot BIOSs, VGA BIOS

128 Kbytes

FFFA0000 CMOS data

128 Kbytes

FFFC0000 Unused

128 Kbytes