SMC Networks 486DX4 - Manual (Page 32)

AR-B1462 User¡ ¦s Guide
3-14
3.2.14 CPU Setting
The AR-B1462 accepts many types of microprocessors such as Intel/AMD/Cyrix 486DX/DX2/DX4. All of these
CPUs include an integer processing unit, floating-point processing unit, memory-management unit, and cache.
They can give a two to ten-fold performance improvement in speed over the 386 processor, depending on the
clock speeds used and specific application. Like the 386 processor, the 486 processor includes both segment-
based and page-based memory protection schemes. The instruction of processing time is reduced by on-chip
instruction pipelining. By performing fast, on-chip memory management and caching, the 486 processor relaxes
requirements for memory response for a given level of system performance.
(1) CPU Logic Core Voltage Select (M6)
P3
1
3
5
P4
3.45V -- Factory Default Setting
P3
1
3
5
P4
5V
1
2
3
1
2
3
M6
Figure 3-30 M6: CPU Logic Core Voltage
(2) AMD 3X/4X CPU Select (JP11)
1
2
JP11
AMD 4X
1
2
AMD 3X
Factory Default Setting
Figure 3-31 JP11: AMD 3X/4X CPU Select
(3) PCI Clock Select (JP4)
Fixed on the
Factory Setting
JP4
1
2
3
4
5
6
PCICLK=CPUCLK
Figure 3-32 JP4: PCI Clock Select
(4) CPU Base Clock Select (JP3)
PIN1-2 PIN3-4 PIN5-6 Base Clock
Close Close Close 50MHz
Close Close Open 40MHz
Close Open Close 33.3MHz
Close Open Open 25MHz
Open Close Close 20MHz
Open Close Open 16MHz
Open Open Close 12MHz
Open Open Open 8MHz
JP3
1
2
3
4
5
6
Table 3-7 JP3: CPU Base Clock Select