Difference between revisions of "SCI/Specifications/SCI virtual machine/The Sierra PMachine"

SCI/Specifications/SCI virtual machine/The Sierra PMachine (view source)

99 bytes added , 00:42, 8 February 2010

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 ;IP
-:The instruction pointer.10 Points to the currently executing instruction
+:The instruction pointer. Points to the currently executing instruction. In ScummVM this is called the "Program Counter" or PC, which is the more general term.
-Vars an array of 4 values, pointing to the current variables of each mentioned type Object points to the currently executing object.
+;Vars
+:An array of four values, each pointing to the current variables of each mentioned type
+;Object
+:Points to the currently executing object.
 ;SP
-:The current stack pointer. Note that the stack in the original SCI interpreter is used
+:The current stack pointer. Note that the stack in the original SCI interpreter is used bottom-up instead of the more usual top-down.
-bottom-up instead of the more usual top-down.
 The PMachine, apart from the actual instruction pointer, keeps a record of which object is currently executing.
 ==The instruction set==