IDE Controller Registers (D31:F1)
10-8
Intel
82801BA ICH2 Datasheet
10.1.12
SDMA_CNT—Synchronous DMA Control Register
(IDE—D31:F1)
Address Offset:
Default Value:
48h
00h
Attribute:
Size:
R/W
8 bits
10.1.13
SDMA_TIM—Synchronous DMA Timing Register
(IDE—D31:F1)
Address Offset:
Default Value:
4A–4Bh
0000h
Attribute:
Size:
R/W
16 bits
Bit
Description
7:4
Reserved.
3
Secondary Drive 1 Synchronous DMA Mode Enable (SSDE1)—
R/W.
0 = Disable (default).
1 = Enable Synchronous DMA mode for secondary channel drive 1
2
Secondary Drive 0 Synchronous DMA Mode Enable (SSDE0)—
R/W.
0 = Disable (default).
1 = Enable Synchronous DMA mode for secondary drive 0.
1
Primary Drive 1 Synchronous DMA Mode Enable (PSDE1)—
R/W.
0 = Disable (default).
1 = Enable Synchronous DMA mode for primary channel drive 1
0
Primary Drive 0 Synchronous DMA Mode Enable (PSDE0)—
R/W.
0 = Disable (default).
1 = Enable Synchronous DMA mode for primary channel drive 0
Bit
Description
15:14
Reserved.
13:12
Secondary Drive 1 Cycle Time (SCT1)—
R/W. For Ultra ATA mode, the setting of these bits
determines the minimum write strobe cycle time (CT). The DMARDY#-to-STOP (RP) time is also
determined by the setting of these bits.
SCB1 = 0 (33 MHz clk)
SCB1 = 1 (66 MHz clk)
00 = CT 4 clocks, RP 6 clocks
00 = Reserved
01 = CT 3 clocks, RP 5 clocks
01 = CT 3 clocks, RP 8 clocks
10 = CT 2 clocks, RP 4 clocks
10 = CT 2 clocks, RP 8 clocks
11 = Reserved
11 = Reserved
FAST_SCB1 = 1 (133 MHz clk)
00 = Reserved
01 = CT 3 clks, RP 16 clks
10 = Reserved
11 = Reserved
11:10
Reserved.
9:8
Secondary Drive 0 Cycle Time (SCT0)—
R/W. For Ultra ATA mode, the setting of these bits
determines the minimum write strobe cycle time (CT). The DMARDY#-to-STOP (RP) time is also
determined by the setting of these bits.
SCB1 = 0 (33 MHz clk)
SCB1 = 1 (66 MHz clk)
00 = CT 4 clocks, RP 6 clocks
00 = Reserved
01 = CT 3 clocks, RP 5 clocks
01 = CT 3 clocks, RP 8 clocks
10 = CT 2 clocks, RP 4 clocks
10 = CT 2 clocks, RP 8 clocks
11 = Reserved
11 = Reserved
FAST_SCB1 = 1 (133 MHz clk)
00 = Reserved
01 = CT 3 clks, RP 16 clks
10 = Reserved
11 = Reserved
7:6
Reserved.
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