EPC-8A Hardware Reference
32
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
Содержание EPC-8A
Страница 38: ...EPC 8A Hardware Reference 28 ...
Страница 68: ...EPC 8A Hardware Reference 58 ...
Страница 72: ...EPC 8A Hardware Reference 62 ...
Страница 74: ...EPC 8A Hardware Reference 64 ...
Страница 82: ...EPC 8A Hardware Reference 72 ...
Страница 94: ...EPC 8A Hardware Reference 84 ...
Страница 108: ...EPC 8A Hardware Reference 98 ...
Страница 118: ...EPC 8A Hardware Reference 108 ...