MC68HC11KW1 Datasheet, PDF (73/238 Pages) Motorola, Inc – High-density complementary metal oxide semiconductor HCMOS) microcontroller unit

4.4.4 MMSIZ — Memory mapping window size register
Memory mapping window size
(MMSIZ)
Address bit 7 bit 6 bit 5 bit 4 bit 3
$0056 MXGS2 MXGS1 W2SZ1 W2SZ0 0
bit 2
bit 1
bit 0
State
on reset
0 W1SZ1 W1SZ0 0000 0000
The MMSIZ register sets the size of the windows in use and selects whether the on-board
general-purpose chip selects are active for CPU addresses or for expansion addresses.
4
MXGS[2:1] — Memory expansion select for general-purpose chip select 2 or 1
1 (set) – General-purpose chip select 2 or 1 based on expansion address.
0 (clear) – General-purpose chip select 2 or 1 based on 64K byte CPU address.
W2SZ[1:0] — Window 2 size
These bits select the bank size for window 2. The window starting address depends on the
contents of the MMWBR register and continues for the same number of bytes as the selected
window size. Refer to Table 4-10.
Bits 3 and 2 — Not implemented; always read zero.
W1SZ[1:0] — Window 1 size
These bits select the bank size for window 1. The window starting address depends on the
contents of the MMWBR register and continues for the same number of bytes as the selected
window size. Refer to Table 4-10.
Table 4-10 Window size select
WxSZ[1:0]
Window size
0 0 Window disabled
0 1 8K – window can have up to 64 8K byte banks
1 0 16K – window can have up to 32 16K byte banks
1 1 32K – window can have up to 16 32K byte banks
MC68HC11KW1
OPERATING MODES AND ON-CHIP MEMORY
4-29