MC68HC812A4 Datasheet, PDF (136/342 Pages) Motorola, Inc – 16-bit device composed of standard on-chip peripheral modules connected by an intermodule bus. Modules include

Memory Expansion and Chip-Select
8.7 Chip-Select Registers
This section describes the chip-select registers.
8.7.1 Chip-Select Control Register 0
Address: $003C
Bit 7
6
5
4
3
2
1
Bit 0
Read: 0
Write:
CSP1E CSP0E CSDE CS3E CS2E CS1E CS0E
Reset: 0
0
0
0
0
0
0
0
= Unimplemented
Figure 8-16. Chip-Select Control Register 0 (CSCTL0)
Read: Anytime
Write: Anytime
Bits have no effect on the associated pin in single-chip modes.
CSP1E — Chip-Select Program 1 Enable Bit
This bit effectively selects the holes in the memory map. It can be
used in conjunction with CSP0 to select between two 2-Mbyte devices
based on address ADDR21.
1 = Enables this chip-select which covers the space $8000 to
$FFFF or full map $0000 to $FFFF
0 = Disables this chip-select
CSP0E — Chip-Select Program 0 Enable Bit
1 = Enables this chip-select which covers the program space
$8000 to $FFFF
0 = Disables this chip-select
CSDE — Chip-Select Data Enable Bit
1 = Enables this chip-select which covers either $0000 to $7FFF
(CSDHF = 1) or $7000 to $7FFF (CSDHF = 0)
0 = Disables this chip-select
MC68HC812A4 — Rev. 3.0
136
Memory Expansion and Chip-Select
Advance Information
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