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128-BIT 3D MULTIMEDIA ACCELERATOR
RIVA128ZX
56/85
[2]
RAM Type
0 = 16Mbit, 2 or 4 internal bank SGRAM or 16Mbit SDRAM. The BIOS should test the memory to
determine whether it supports 2 or 4 internal banks.
1 = 8Mbit, 2 internal bank SGRAM.
Although a 10K
resistor is used to strap the default state of this bit in RIVA 128 and RIVA128ZX
reference designs, it is ignored by the video BIOS which auto-detects the memory type and con-
figures the RIVA128ZX appropriately.
[1]
Sub-Vendor. This bit indicates whether the PCI Subsystem Vendor field is located in the system
motherboard BIOS oradapter card VGA BIOS. Ifthe Subsystem Vendorfield islocated in the sys-
tem BIOS it must be written by the system BIOS to the PCI configuration space prior to running
any PnP code.
0 = System BIOS (Subsystem Vendor ID and Subsystem ID set to 0x0000)
1 = Adapter card VGA BIOS (Subsystem Vendor ID and Subsystem ID read from ROM BIOS at
location 0x54 - 0x57)
[0]
Bus Speed. This bit indicates the value returned in the 66MHz bit in the PCI Configuration regis-
ters.
0 = RIVA128ZX PCI interface is 33MHz
1 = RIVA128ZX is 66MHz capable
The following example configuration is shown in Figure 65:
Subsystem Vendor ID initialized to 0 and writeable by system BIOS (see Appendix A, page 76)
8Mbit, 2 internal bank, SGRAM
128-bit framebuffer interface
AGP 2X mode enabled including 66MHz PCI 2.1 compliant subset
Using 13.5000MHz crystal
TV output mode is NTSC
Figure 65.
Example motherboard configuration
10K
RIVA128ZX
FBA[1
]
FBA[2]
FBA[3]
SGRAM
array
VDD (3.3V)
A
FBA[4]
FBA[5]
FBA[8]
FBA[6]
FBA[7]
FBA[0
]
FBA[9]
FBA[10]