Intel 386 - Manual (Page 441)

Intel386™ EX EMBEDDED MICROPROCESSOR USER’S MANUAL
14-6
Example 2
This example establishes four 4-Kbyte address blocks starting at 0000000H, 0002000H,
0004000H, and 0006000H (4-Kbyte boundaries).
Because the least-significant 0 in the channel’s mask is in bit position 2, this channel’s active ad-
dress block size is 2
2 = 4 Kbytes. Because there are two 1’s to the left of the right-most 0 in the
channel’s mask, the block is repeated 2 2 = 4 times. Also, because there are no 1’s in the channel
mask where there are 1’s in the channel address, the channel address is the starting address of the
lowest active address block. In this example, each active 4-Kbyte address block in memory is fol-
lowed by an inactive 4-Kbyte address block and each active address block starts on a 4-Kbyte
address boundary.
15 1
15-bit Channel Address 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
15-bit Channel Mask 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1
25 0
Channel Active Address 0 0 0 0 0 0 0 0 0 0 0 X X 0 X X X X X X X X X X X X
Maximum
Memory Address
0007000H
Active 0006FFFH
0006000H
0005FFFH
0005000H
Active 0004FFFH
0004000H
0003FFFH
0003000H
Active 0002FFFH
0002000H
0001FFFH
0001000H
Active 0000FFFH
0000000H