SST49LF004B-33-4C-EI SST [Silicon Storage Technology, Inc], SST49LF004B-33-4C-EI Datasheet - Page 17

• Manufacturer Part Number: SST49LF004B-33-4C-EI
• Description: 4 Mbit LPC Firmware Flash
• Manufacturer: SST [Silicon Storage Technology, Inc]

4 Mbit LPC Firmware Flash
SST49LF004B
Multiple Device Selection
Multiple LPC flash devices may be strapped to increase
memory densities in a system. The four ID pins, ID[3:0],
allow up to 16 devices to be attached to the same bus by
using different ID strapping in a system. BIOS support, bus
loading, or the attaching bridge may limit this number. The
boot device must have an ID of 0000b (determined by
ID[3:0]); subsequent devices use incremental numbering.
Equal density must be used with multiple devices.
Multiple Device Selection for
Firmware Memory Cycle
For Firmware Memory Read/Write cycles, hardware strap-
ping values on ID[3:0] must match the values in IDSEL
field. See Table 8 for multiple device selection configura-
tions. The SST49LF004B will compare the IDSEL field with
ID[3:0]'s strapping values. If there is a mismatch, the device
will ignore the reminder of the cycle.
TABLE 8: F
©2003 Silicon Storage Technology, Inc.
Device #
0 (Boot device)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
S
IRMWARE
ELECTION
M
C
EMORY
ONFIGURATION
ID[3:0]
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
M
ULTIPLE
D
IDSEL
EVICE
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
T8.0 1232
17
Multiple Device Selection for LPC Memory Cycle
For LPC Memory Read/Write cycles, ID information is
included in the address bits of every cycle. The ID bits in
the address field are the inverse of the hardware strapping.
The address bits (A
device with proper IDs. See Table 9 for multiple device
selection configurations. The SST49LF004B will compare
these bits with ID[3:0]’s strapping values. If there is a mis-
match, the device will ignore the remainder of the cycle.
TABLE 9: LPC M
Device #
0 (Boot device)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
S
ELECTION
EMORY
23
, A
C
ID[3:0]
21
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
ONFIGURATION
:A
M
19
ULTIPLE
) are used to select the
S71232-02-000
D
A
EVICE
23,
1111
1110
1101
1100
1011
1010
1001
1000
0111
0110
0101
0100
0011
0010
0001
0000
A
Data Sheet
21
:A
19
T9.0 1232
12/03