3. Functional Blocks
13
The connector pinout adheres to the CompactPCI standard. For more information on
the CompactPCI standard contact Ziatech at
http://www.ziatech.com
.
VGA CONTROLLER
The ZT 6631 is based on the Cirrus Logic 5434 VGA controller. This controller is a
highly integrated 64-bit GUI engine, optimized for handling graphic-intensive
environments such as Windows and OS2. The controller uses a 64-bit data path to the
video memory, allowing it to surpass many VRAM based controllers in performance. In
addition, the 5434 contains several other performance enhancers such as a BitBLT
accelerator, linear addressing, hardware cursor, color expansion and memory mapped
I/O.
The 5434 is hardware register compatible with the IBM VGA standard and can support
resolutions up to 1280 x 1024. The 5434 contains an integrated 24-bit RAMDAC,
allowing the display of 16.8 million colors.
The 5434 supports the use of an on-board EEPROM to save monitor setting. This
allows the user to set up the ZT 6631 for the best refresh rates and video modes for a
particular monitor. The utility CLMODE.EXE supplied on the
DOS drivers and utilities
disk can be used to save these settings to EEPROM. See Chapter 5 for more
information on using the
CLMODE.EXE
utility.
Please note that once these settings are saved to EEPROM, the ZT 6631 always
powers up using these modes and refresh rates. Make sure to reset the ZT 6631 to the
default values (all modes using 60 Hz refresh rates) before switching to a different
monitor that might not be able to handle the previous modes and refresh rates.
VIDEO MEMORY
The ZT 6631 can be ordered with up to 4 Mbytes of high speed 80 ns fast page mode
DRAM, allowing it to support high resolution color graphics modes such as 1280 x 1024
x 64K colors. The memory is organized as eight 256K x 16-bit DRAMs. The Cirrus Logic
5434 controls accesses to the display memory and arbitrates between the display
refresh requirements and CPU accesses. The address space occupied by the video
memory depends on the video mode selected. The "
Display Memory Address Map
"
table summarizes the address space for various video modes.
In order to allow for all possible modes of operation, memory address space from
A0000 to C7FFFh should be reserved for the display memory and video BIOS. If certain
video modes, such as monochrome text, are not used, it is possible to use the memory
address space corresponding to the unused mode.
The Cirrus Logic drivers for Windows (supplied on the Drivers and Utilities disks) use
linear addressing to increase performance. Linear addressing allows the controller to
see a contiguous area of memory instead of 64 K pages as with the standard VGA
implementation. The ZT 6631's linear addressing region is mapped in the upper
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