Programs can now pin specific routines to specific vectors in SplitBit assembly. Added snake game.

Programs/testPrograms/pinnedVectorTest.asm

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+; Vectors with numbers written down, and vectors numbered by the assembler, in one program.
+;
+; A software vector number matters only when two separately assembled programs have to
+; agree about it. The system's services are the case that exists today: something calls
+; osExit without having been assembled alongside whatever implements it, so both sides
+; have to mean the same number by that name.
+;
+; Numbers from 16 to 63 are for exactly that and are never handed out. Everything from 64
+; up is handed out in the order it is written, and belongs to one program.
+;
+; This pins one at each end of the reserved range and leaves a third to the assembler. All
+; three are then called by name, which is the only way a program ever refers to one - the
+; number is a fact about the machine, not something a program says twice.
+;
+; Correct output is:
+;   pinned vectors
+;   twenty
+;   sixty three
+;   automatic
+;   done
+
+#Include console.asm
+
+#Program
+
+start:
+  SETD.0 Banner
+  CALL printString
+  CALL newLine
+
+  SWI atTwenty
+  SWI atSixtyThree
+  SWI automatic
+
+  SETD.0 DoneText
+  CALL printString
+  CALL newLine
+  HALT
+
+; Each of these says which one it is, so a number going to the wrong place is a wrong word
+; rather than a silence.
+twentyHandler:
+  SETD.0 TwentyText
+  CALL printString
+  CALL newLine
+  RETI
+
+sixtyThreeHandler:
+  SETD.0 SixtyThreeText
+  CALL printString
+  CALL newLine
+  RETI
+
+automaticHandler:
+  SETD.0 AutomaticText
+  CALL printString
+  CALL newLine
+  RETI
+
+#Data
+
+Banner:
+"pinned vectors"
+TwentyText:
+"twenty"
+SixtyThreeText:
+"sixty three"
+AutomaticText:
+"automatic"
+DoneText:
+"done"
+
+#Vectors
+
+  Boot                  start
+  atTwenty      0d20    twentyHandler
+  atSixtyThree  0d63    sixtyThreeHandler
+  automatic             automaticHandler