ICS9148-47 Datasheet, PDF (4/9 Pages) Integrated Circuit Systems – Pentium/ProTM System Clock Chip

ICS9148-47
Serial Bitmap
Byte 3: Functionality & Frequency Select
& Spread Slect Register
Bit
7
Bit
654
000
001
010
6:4 011
100
101
110
111
Description
(Reserved)
CPU
PCI
Spread
Percentage
68.5
34.25 ±0.5% Center
75.0
37.5 ±0.5% Center
83.3
41.6 ±0.5% Center
66.6
33.3 ±0.5% Center
103
34.3 ±0.5% Center
112
37.3 ±0.5% Center
133.3 44.43 ±0.5% Center
100
33.33 ±0.5% Center
PWD
0
0
0 - Frequency is selected by hardware select
3
SEL100/66.6#
0
1 - Frequency is selected by 6:4 above
2
(Reserved)
00 - Normal operation
10
01 - Test mode
10 - Spread sprectrum ON
00
11 - Tristate all outputs
Notes: 1 = Enabled; 0 = Disabled, outputs held low
Byte 5:
Bit
Pin#
Pin Name
PWD
Description
Bit Value = 0 Bit Value = 1
7 4 PCICLK_F 1
Disabled
(low)
Enabled
6 11 PCICLK5 1
Disabled
(low)
Enabled
5 10 PCICLK4 1
Disabled
(low)
Enabled
4-
-
0
(Reserved) (Reserved)
3 8 PCICLK3 1
Disabled
(low)
Enabled
2 7 PCICLK2 1
Disabled
(low)
Enabled
1 6 PCICLK1 1
Disabled
(low)
Enabled
0 5 PCICLK0 1
Disabled
(low)
Enabled
Notes: 1 = Enabled; 0 = Disabled, outputs held low
Byte 4:
Bit
Pin#
Pin Name
PWD
Description
Bit Value = 0 Bit Value = 1
7-
-
-
(Reserved) (Reserved)
6-
-
-
(Reserved) (Reserved)
5-
-
-
(Reserved) (Reserved)
4-
-
-
(Reserved) (Reserved)
3-
-
-
(Reserved) (Reserved)
2 21 CPUCLK1 1
Disabled
(low)
Enabled
1-
-
0
(Reserved) (Reserved)
0 22 CPUCLK0 1
(Disabled)
(low)
Enabled
Notes: 1 = Enabled; 0 = Disabled, outputs held low
Note: PWD = Power-Up Default
Byte 6:
Bit
Pin# Pin Name PWD
Description
Bit Value = 0 Bit Value = 1
7-
-
0
(Reserved) (Reserved)
6-
-
0
(Reserved) (Reserved)
5 24 IOAPIC 1
Disabled
(low)
Enabled
4-
-
0
(Reserved) (Reserved)
3-
-
0
(Reserved) (Reserved)
2-
-
0
(Reserved) (Reserved)
1 27 REF0
1
(Disabled)
(low)
Enabled
0 27 REF0
1
(Disabled)
(low)
Enabled
Notes:
1 = Enabled; 0 = Disabled, outputs held low
For pin 27, there are 2 output stages together for 1 pin. These 2
latches must be both 0 or 1 simultaneously or there will be a short to
ground if one is disabled and the other is running.
4