Intel 8XC196NP manual Windowed Base Addresses, 2.1 32-byte Windowing Example, 80C196NU Only

8XC196NP, 80C196NU USER’S MANUAL

	Table 5-11. Windowed Base Addresses
Window Size	WSR Windowed Base Address	WSR1 Windowed Base Address
		(Base Address in Lower Register File)
	(Base Address in Lower Register File)
		80C196NU Only
32-byte	00E0H	0060H
64-byte	00C0H	0040H
128-byte	0080H	—

Appendix C includes a table of the windowable SFRs with the window selection register values and direct addresses for each window size. The following examples explain how to determine the WSR value and direct address for any windowable location. An additional example shows how to set up a window by using the linker locator.

5.3.2.132-byte Windowing Example

Assume that you wish to access location 014BH (a location in the upper register file used for gen- eral-purpose register RAM) with direct addressing through a 32-byte window. Table 5-10 on page 5-17 shows that you need to write 4AH to the window selection register. It also shows that the base address of the 32-byte memory area is 0140H. To determine the offset, subtract that base ad- dress from the address to be accessed (014BH – 0140H = 000BH). Add the of fset to the base ad- dress of the window in the lower register file (from Table 5-11). The direct address is 00EBH (000BH + 00E0H) for a WSR window or 006BH (000BH + 0060H) for a WSR1 window.

5.3.2.264-byte Windowing Example

Assume that you wish to access the SFR at location 1F8CH with direct addressing through a 64- byte window. Table 5-10 on page 5-17 shows that you need to write 3EH to the window selection register. It also shows that the base address of the 64-byte memory area is 1F80H. To determine the offset, subtract that base address from the address to be accessed (1F8CH – 1F80H = 000CH). Add the offset to the base address of the window in the lower register file (from Table 5-11). The direct address is 00CCH (000CH + 00C0H) for a WSR window or 004CH (000CH + 0040H) for a WSR1 window.

5.3.2.3128-byte Windowing Example

Assume that you wish to access the SFR at location 1F82H with direct addressing through a 128- byte window. Table 5-11 on page 5-18 shows that you need to write 1FH to the window selection register. It also shows that the base address of the 128-byte memory area is 1F80H. To determine the offset, subtract that base address from the address to be accessed (1F82H – 1F80H = 0002H). Add the offset to the base address of the window in the lower register file (from Table 5-11). The direct address is 0082H (0002H + 0080H).

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