Intel 80C186XL, User Manual

Page: 168 / 405

6-13
CHIP-SELECT UNIT
6.4.2.2 LCS Active Range
The LCS starting address is fixed at zero in memory address space; its ending address is the pro-
grammed block size minus one. Table 6.3 defines the acceptable values for the field (U17:10) in
the LMCS register that determines the LCS block size and ending address.
6.4.2.3 MCS Active Range
The starting and ending addresses of the individual MCS chip-selects are determined by the base
address programmed in the MMCS register and the block size programmed in the MPCS register
(see Table 6-4 and Figure 6-10). The base address must be an integer multiple of the block size.
Table 6-5 lists the allowable block sizes and base address limitations.
Table 6.3 LCS Active Range
LMCS Field
U17:10
Block Size
(Kbytes)
Ending Address
00H 1 003FFH
01H 2 007FFH
03H 4 00FFFH
07H 8 01FFFH
0FH 16 03FFFH
1FH 32 07FFFH
3FH 64 0FFFFH
7FH 128 1FFFFH
FFH 256 3FFFFH
Table 6-4. MCS Active Range
Chip-
Select
Active Range
Start Address Ending Address
MCS0 Base Base + (1/4 block size –1)
MCS1 Base + 1/4 block size Base + (1/2 block size –1)
MCS2 Base + 1/2 block size Base + (3/4 block size –1)
MCS3 Base + 3/4 block size Base + (block size – 1)