Intel Embedded Intel486

EMBEDDED Intel486™ PROCESSOR HARDWARE REFERENCE MANUAL
4-6
Figure 4-4 shows the Intel486 processor address bus interface to 32-, 16- and 8-bit memories. To
address 16-bit memories the byte enables must be decoded to produce A1, BHE# and BLE# (A0).
For 8-bit wide memories the byte enables must be decoded to produce A0 and A1. The same byte
select logic can be used in 16- and 8-bit systems, because BLE# is exactly the same as A0 (see
Table 4-5).
Figure 4-4. Addressing 16- and 8-Bit Memories
BE3#–BE0# can be decoded as shown in Table 4-5. The byte select logic necessary to generate
BHE# and BLE# is shown in Figure 4-5.
Intel486™
Processor
BS16#
BS8#
Address Bus (A31–A2, BE3#–BE0#)
A31–A2
BE3#–BE0#
BHE#, BLE#, A1
A0 (BLE#), A1
A31–A2
8-Bit Memory
16-Bit Memory
32-Bit Memory
Byte
Select Logic
Address
Decode