RIVA128ZX Datasheet, PDF (79/85 Pages) STMicroelectronics – 128-BIT 3D MULTIMEDIA ACCELERATOR

128-BIT 3D MULTIMEDIA ACCELERATOR
RIVA128ZX
Byte offset 0x3F - 0x3C
0x3F
0x3E
0x3D
0x3C
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
MAX_LAT Register (0x3F)
Bits
31:24
Function
The MAX_LAT bits contain the maximum time the RIVA128ZX requires to
gain access to the PCI bus. This read-only register is used to specify the
RIVA128ZX’s desired settings for Latency Timer values. The value specifies a
period of time in units of 250ns.
1=250ns
RWI
R-1
MIN_GNT Register (0x3E)
Bits
23:16
Function
The MIN_GNT bits contain the length of the burst period the RIVA128ZX
needs, assuming a clock rate of 33MHz. This read-only register is used to
specify the RIVA128ZX’s desired settings for Latency Timer values. The value
specifies a period of time in units of 250ns.
3=750ns
RWI
R-3
Interrupt Pin Register (0x3D)
Bits Function
15:8 The INTERRUPT_PIN bits contain the interrupt pin the device (or device func-
tion) uses. A value of 1 corresponds to INTA#.
RWI
R-1
Interrupt Line Register (0x3C)
Bits Function
RWI
7:0
The INTERRUPT_LINE bits contain the interrupt routing information. POST R W 0xFF
software will write the routing information into this register as it initializes and
configures the system. The value in this field indicates which input of the sys-
tem interrupt controller(s) the RIVA128ZX’s interrupt pin is connected to.
Device drivers and operating systems can use this information to determine
priority and vector information. INTERRUPT_LINE is initialized to 0xFF (no
connection) at reset.
0=Interrupt line IRQ0
1=Interrupt line IRQ1
0xF=Interrupt line IRQ15
0xFF=No interrupt line connection (reset value)
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