Difference between revisions of "84PCE:RAM:D01508"

Latest revision as of 07:30, 26 May 2016

Unofficial Name: lastEntryStkPtr

Memory Address: D01508h

Length: 3 bytes

This is a pointer to the next available byte in the user entry stack.

@@ Line 1: / Line 1: @@
-[[Category:84PCE:RAM:By Address|D0053F - tempSP]] [[Category:84PCE:RAM:By Name|tempSP]]
+[[Category:84PCE:RAM:By Address|D01508 - lastEntryStkPtr]] [[Category:84PCE:RAM:By Name|lastEntryStkPtr]]
 == Synopsis ==
-'''Unofficial Name:''' tempSP
+'''Unofficial Name:''' lastEntryStkPtr
-'''Memory Address:''' D0053Fh
+'''Memory Address:''' D01508h
 '''Length:''' 3 bytes
-When the OS is checking the stack depth, it uses this region of memory to load hl with sp. For instance:
+This is a pointer to the next available byte in the user entry stack.
- ld (tempSP),sp
- ld hl,(tempSP)
-It can generally be used as a temporary data location, although it may be written to at some points.
-==Why this is silly==
-However, it is simply beyond me why they didn't simply do this, to save a ton of bytes and speed.
- or a,a
- sbc hl,hl
- add hl,sp