Specifications

33
EPC-30 Hardware Reference
Page 37
configuration in the SIMM, the DRAM controller functions as two
independent controllers, managing each bank of DRAM in an interleaved
fashion. The controller determines accesses to each DRAM bank.
BIOS Flash EPROM
The system BIOS and video BIOS reside in a single 2MB boot-block flash
EPROM (Intel 28F200BV-T or equivalent). It is based on the Phoenix
PicoBIOS code base. It includes the video BIOS, supplied by Cirrus, and
support for flat panel displays. The BIOS includes support for a set of three
different displays.
The most common types of displays that work with the EPC-30 board are
Monochrome, Passive Color, and TFT Color. Refer to the next section in this
chapter, as well as Appendix E, LCD Flat Panel Interface, for more
information.
The boot-block flash EPROM allows BIOS changes and upgrades to be
loaded and programmed into the flash BIOS after the board leaves the
factory. It is anticipated that this feature may be required to support different
flat-panel displays, without requiring that the flash device be replaced.
The EPC-30 uses a signal on the miscellaneous expansion header to force an
update of the BIOS. This signal is connected to an input pin of the R380EX,
and it is used when the BIOS is so corrupted that the operating system does
not boot. The BIOS will then be updated from the serial COMA port. Refer
to Appendix D, Reflashing the BIOS, for more details on this operation.
A jumper is provided to enable programming of the boot block. Selection of
the source of the chip select (either the R380 BIOS CS or the 386EX UCS
signal) for the BIOS component is controlled by resistor options. Refer to
Chapter 2, Installation and Configuration.
Super VGA/Flat Panel Controller Subsystem
A VGA-compatible video and flat-panel display controller can be provided
on the CPU board. The video subsystem is implemented with a Cirrus CL-
GD6245 along with 512KB of video memory implemented with one
256Kx16 DRAM device.
The Cirrus VGA chip supports a variety of 640x480 LCDs along with
simultaneous CRT and LCD operation. CRT resolutions of 1024x768 with
16 colors or 800x600 with 256 colors and up to 64 gray shades (at 640x480)
with monochrome STN and TFT LCDs may be obtained. The VGA
controller is on the Intel386 EX local bus.