CHIP-SELECT UNIT

The UMCS and LMCS registers can be programmed in any sequence. To program the MCS and PCS chip-selects, follow this sequence:

1.Program the MPCS register

2.Program the MMCS register to enable the MCS chip-selects.

3.Program the PACS register to enable the PCS chip-selects.

6.4.2Programming the Active Ranges

The active ranges of the chip-selects are determined by a combination of their starting or ending addresses and block sizes. This section describes how to control the active range of each chip- select.

6.4.2.1UCS Active Range

The UCS starting address is 100000H (1 Mbyte) minus the block size; its ending address is fixed at 0FFFFFH.Table 6-2 defines the acceptable values for the field (U17:10) in the UMCS register that determines the UCS block size and starting address.

Table 6-2. UCS Block Size and Starting Address

UMCS Field

Block Size

Starting Address

U17:10

(Kbytes)

 

 

 

 

00H

256

0C0000H

 

 

 

80H

128

0E0000H

 

 

 

C0H

64

0F0000H

 

 

 

E0H

32

0F8000H

 

 

 

F0H

16

0FC000H

 

 

 

F8H

8

0FE000H

 

 

 

FCH

4

0FF000H

 

 

 

FEH

2

0FF800H

 

 

 

FFH

1

0FFC00H

 

 

 

6-12

Page 167
Image 167
Intel 80C186XL, 80C188XL user manual Programming the Active Ranges, UCS Active Range, UCS Block Size and Starting Address