
60
AMD Geode SC1200/SC1201 Processor Data Book
Signal Definitions
Revision 7.1
3.2
Strap Options
Several balls are read at power-up that set up the state of
the SC1200/SC1201 processor. These balls are typically
multiplexed with other functions that are outputs after the
power-up sequence is complete. The SC1200/SC1201 pro-
cessor must read the state of the balls at power-up and the
internal PU or PD resistors do not guarantee the correct
state will be read. Therefore, it is required that an external
PU or PD resistor with a value of 1.5 K
be placed on the
balls listed in
Table 3-6. The value of the resistor is impor-
tant to ensure that the proper state is read during the
power-up sequence. If the ball is not read correctly at
power-up, the SC1200/SC1201 processor may default to a
state that causes it to function improperly, possibly result-
ing in application failure.
Table 3-6. Strap Options
Strap
Option
Muxed With
Ball No.
Nominal
Internal
PU or PD
External PU/PD Strap Settings
Register References
EBGA
TEPBGA
Strap = 0 (PD)
Strap = 1 (PU)
CLKSEL0
RD#
F3
B8
PD100
CLKSEL strap options.
GCB+I/O Offset 1Eh[9:8] (aka
CCFC register bits [9:8]) (RO):
Value programmed at reset by
CLKSEL[1:0].
GCB+I/O Offset 10h[3:0] (aka
MCCM register bits [3:0]) (RO):
Value programmed at reset by
CLKSEL[3:0].
GCB+I/O Offset 1Eh[3:0] (aka
CCFC register bits [3:0]) (R/W,
but write not recommended):
Value programmed at reset by
CLKSEL[3:0].
Note: Values for GCB+I/O Offset
10h[3:0] and 1Eh[3:0] are not the
same.
CLKSEL1
SOUT1
B27
AF3
PD100
CLKSEL2
SOUT2
AK3
D29
PD100
CLKSEL3
SYNC
AL13
P30
PD100
BOOT16
ROMCS#
G4
C8
PD100
Enable boot
from 8-bit ROM
Enable boot
from 16-bit
ROM
GCB+I/O Offset 34h[3] (aka MCR
register bit 3) (RO): Reads back
strap setting.
GCB+I/O Offset 34h[14] (R/W):
Used to allow the ROMCS# width
to be changed under program
control.
TFT_PRSNT
SDATA_OUT
AK13
P29
PD100
TFT not muxed
onto Parallel
Port
TFT muxed
onto Parallel
Port
GCB+I/O Offset 30h[23] (aka
PMR register bit 23) (R/W):
Reads back strap setting.
LPC_ROM
PCICLK1
E4
D6
PD100
Disable boot
from ROM on
LPC bus
Enable boot
from ROM on
LPC bus
F0BAR1+I/O Offset 10h[15] (R/
W): Reads back strap setting and
allows LPC ROM to be changed
under program control.
FPCI_MON
PCICLK0
D3
A4
PD100
Disable Fast-
PCI, INTR_O,
and SMI_O
monitoring sig-
nals.
Enable Fast-
PCI, INTR_O,
and SMI_O
monitoring sig-
nals. (Useful
during debug.)
GCB+I/O Offset 34h[30] (aka
MCR register bit 30) (RO): Reads
back strap setting.
Note:
For normal operation,
strap
this
signal
low
using a 1.5 K
resistor.
DID0
GNT0#
D4
C5
PD100
Defines the system-level chip ID.
GCB+I/O Offset 34h[31,29] (aka
MCR register bits 31 and 29)
(RO): Reads back strap setting.
Note:
These signals should be
connected to a 1.5 K
PD resistor to ensure a
low level at power-up.
DID1
GNT1#
D2
C6
PD100
Note:
Accuracy of internal PU/PD resistors: 80K to 250K.
Location of the GCB (General Configuration Block) cannot be determined by software. See the AMD Geode SC1200/
SC1201 Processor Specification Update document.