Specifications

CHAPTER 2
Hardware Design
24 Audio System
Video Timing 2
To accommodate the various VGA and SVGA modes on the Macintosh monitors, the
video controller must have its timing parameters changed by the BIOS. To do that, the
Macintosh software reads the video sense lines and loads the appropriate values for the
video BIOS before starting up the PC. The system and video BIOS reside in Macintosh
system memory and can be modified by the software.
Video ICs 2
Video support for the cards is provided by an ATI-264CT VGA controller and by the
video DRAM.
The ATI-264CT VGA controller is a 208-pin graphics controller IC with a built-in
accelerator, referred to as the coprocessor. It is compatible with the VGA display adapter
and provides for modes 0–7 and D–13h. SVGA modes for 640 by 480 and 800 by 600 are
also supported up to 64K colors, and SVGA modes for 1024 by 768 up to 256 colors. You
should refer to the reference material provided with the device for detailed information
about the controller.
Each card has 1 MB by 32 bits of installed video DRAM. The 12” card also has sockets
that allow you to expand video DRAM capacity to 2 MB, with a 64-bit data path and
higher resolution support.
Audio System 2
The sound system for the cards is built around a Creative Technologies Vibra 16S 16-bit
audio IC and a synthesizer chip set that includes a Yamaha OPL3-L FM synthesizer and
YAC516 DAC IC. These ICs provide the cards with 16-bit stereo Sound Blaster Pro
capabilities.
Note
Sound Blaster Pro products, such as the audio IC and the synthesizer
chip set, support the sound capabilities of PC systems, in this case, the
12” and 7” cards. Sound Blaster Pro installation software is a de facto
standard set by Creative Technologies. ◆