W78E054D Datasheet, PDF (17/89 Pages) List of Unclassifed Manufacturers – 8-bit microcontroller

W78E054D/W78E052D Data Sheet
8.2.2 Bit addressable Locations
The Scratch-pad RAM area from location 20h to 2Fh is byte as well as bit addressable. This means
that a bit in this area can be individually addressed. In addition some of the SFRs are also bit ad-
dressable. The instruction decoder is able to distinguish a bit access from a byte access by the type of
the instruction itself. In the SFR area, any existing SFR whose address ends in a 0 or 8 is bit address-
able.
8.2.3 Stack
The scratch-pad RAM can be used for the stack. This area is selected by the Stack Pointer (SP),
which stores the address of the top of the stack. Whenever a jump, call or interrupt is invoked the re-
turn address is placed on the stack. There is no restriction as to where the stack can begin in the
RAM. By default however, the Stack Pointer contains 07h at reset. The user can then change this to
any value desired. The SP will point to the last used value. Therefore, the SP will be incremented and
then address saved onto the stack. Conversely, while popping from the stack the contents will be read
first, and then the SP is decreased.
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Publication Release Date: Jun 9, 2015
Revision A13