AR-B1476 User
’
s Guide
3-11
3.2.12 CPU Setting
The AR-B1476 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, which is 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 (P1 & P2)
P1
1
2
3
4
5
P2
3.45V -- Factory Default Setting
6
P1
1
2
3
4
5
P2
5V
6
1
2
3
1
2
3
Figure 3-25 P1 & P2: CPU Logic Core Voltage
(2) AMD 3X/4X CPU Select (JP5)
1
2
JP5
AMD 4X
1
2
JP5
AMD 3X
Factory Default Setting
Figure 3-26 JP5: AMD 3X/4X CPU Select
(3) PCI Clock Select (JP7)
JP7
1
2
3
4
5
Factory Default Setting
6
JP7
1
2
3
4
5
6
PCICLK=CPUCLK
PCICLK=1/2 CPUCLK
Figure 3-27 JP7: PCI Clock Select
(4) CPU Clock Multiplier Select (JP6)
A B
Base
Clock
Note
Close Close 50MHz
Open Close 40MHz
Close Open
33.3MHz
Factory
Preset
Open Open 25MHz
JP6
1
2
3
4
5
6
A B C
Table 3-6 JP6: CPU Clock Multiplier Select
