Intel Microcontroller User Manual
8XC196NP, 80C196NU USER’S MANUAL
5-14
5.3.1
Selecting a Window
The window selection register (Figure 5-5) has two functions. The HLDEN bit (WSR.7) enables
and disables the bus-hold protocol (see Chapter 13, “Interfacing with External Memory”); it is
unrelated to windowing. The remaining bits select a window to be mapped into the top of the low-
er register file. Window selection register 1 (Figure 5-6) selects a second window to be mapped
into the middle of the 80C196NU’s lower register file.
and disables the bus-hold protocol (see Chapter 13, “Interfacing with External Memory”); it is
unrelated to windowing. The remaining bits select a window to be mapped into the top of the low-
er register file. Window selection register 1 (Figure 5-6) selects a second window to be mapped
into the middle of the 80C196NU’s lower register file.
Table 5-8 provides a quick reference of WSR values for windowing the peripheral SFRs. Table
5-9 on page 5-15 lists the WSR values for windowing the upper register file.
5-9 on page 5-15 lists the WSR values for windowing the upper register file.
WSR
Address:
Reset State:
0014H
00H
The window selection register (WSR) has two functions. One bit enables and disables the bus-hold
protocol. The remaining bits select windows. Windows map sections of RAM into the top of the lower
register file, in 32-, 64-, or 128-byte increments. PUSHA saves this register on the stack and POPA
restores it.
protocol. The remaining bits select windows. Windows map sections of RAM into the top of the lower
register file, in 32-, 64-, or 128-byte increments. PUSHA saves this register on the stack and POPA
restores it.
7
0
HLDEN
W6
W5
W4
W3
W2
W1
W0
Bit
Number
Bit
Mnemonic
Function
7
HLDEN
HOLD#, HLDA# Protocol Enable
This bit enables and disables the bus-hold protocol (see Chapter 13,
“Interfacing with External Memory”). It has no effect on windowing.
“Interfacing with External Memory”). It has no effect on windowing.
1 = enable
0 = disable
0 = disable
6:0
W6:0
Window Selection
These bits specify the window size and window number. See Table 5-8
on page 5-15 or Table 5-9 on page 5-15.
on page 5-15 or Table 5-9 on page 5-15.
Figure 5-5. Window Selection (WSR) Register