Interrupt system implemented, some new programs.

Programs/testPrograms/diagnostics/alignOutside.asm

@@ -0,0 +1,11 @@
+; #Align before either segment has been opened.
+;
+; The directive moves a cursor along, and outside a segment there is no cursor for
+; it to move, so this has to be an error rather than quietly doing nothing.
+
+  #Align 0x100
+
+#Program
+
+start:
+  HALT

Programs/testPrograms/diagnostics/bareAlign.asm

@@ -0,0 +1,10 @@
+; #Align with no number after it.
+;
+; Without this check the next token is taken as the alignment, which would silently
+; align to whatever the following instruction happened to be worth.
+
+#Program
+
+start:
+  HALT
+  #Align

Programs/testPrograms/diagnostics/bareInclude.asm

@@ -0,0 +1,10 @@
+; Deliberately broken, to check that the assembler still catches it.
+; The file ends straight after the keyword, so there is no name to read. This
+; used to walk into whatever the array happened to hold and crash.
+
+#Program
+
+start:
+  HALT
+
+#Include

Programs/testPrograms/diagnostics/bareSWI.asm

@@ -0,0 +1,10 @@
+; SWI with nothing after it.
+;
+; Without the operand check this assembles, and SWI quietly takes the next
+; instruction as its vector number. Everything after it then shifts by a byte.
+
+#Program
+
+start:
+  SWI
+  HALT

Programs/testPrograms/diagnostics/duplicateLabel.asm

@@ -0,0 +1,14 @@
+; Deliberately broken, to check that the assembler still catches it.
+; The same name is defined twice, which used to be accepted silently, with every
+; reference quietly resolving to whichever definition came first.
+
+#Program
+
+start:
+  BRI twice
+
+twice:
+  HALT
+
+twice:
+  HALT

Programs/testPrograms/diagnostics/duplicateVector.asm

@@ -0,0 +1,20 @@
+; Two handlers claiming the same vector.
+;
+; Device lines name a port directly, so two of them can collide even though the
+; assembler numbers the named vectors itself.
+
+#Program
+
+start:
+  HALT
+
+firstHandler:
+  RETI
+
+secondHandler:
+  RETI
+
+#Vectors
+
+  Device 0x10  firstHandler
+  Device 0x10  secondHandler

Programs/testPrograms/diagnostics/unknownVector.asm

@@ -0,0 +1,10 @@
+; SWI names something that was never given a handler.
+;
+; A vector name is not a label, so the usual "undefined label" error would be
+; misleading. It has to say that the name needs a #Vectors entry.
+
+#Program
+
+start:
+  SWI neverDeclared
+  HALT