Intel 386

14-5
CHIP-SELECT UNIT
Example 1
This example establishes a single 32-Kbyte address block starting at 1340000H (a 32-Kbyte
boundary). In this example, the 15-bit channel address is the starting address of the channel’s ac-
tive address block (because there are no 1’s in the channel mask where there are 1’s in the channel
address)
.
Because the least-significant 0 in the channel’s mask is in bit position 5, this channel’s active ad-
dress block size is 2
5
= 32 Kbytes. Because there are no 1’s to the left of the right-most 0 in the
channel’s mask, the block is not repeated.
15 1
15-bit Channel Address 0 1 0 0 1 1 0 1 0 0 0 0 0 0 0
15-bit Channel Mask 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1
25 0
Channel Active Address 0 1 0 0 1 1 0 1 0 0 0 X X X X X X X X X X X X X X X
Active
1347FFFH
1340000H