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

Jump to navigation Jump to search
(→‎The PMachine “registers”: Fix messed up docs)
Line 31: Line 31:


;IP           
;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
;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 PMachine, apart from the actual instruction pointer, keeps a record of which object is currently executing.


==The instruction set==
==The instruction set==
1,079

edits

Navigation menu