Add failing tests for add and sub on locations other than a.

tests/SixtyPical Analysis.md

@@ -852,6 +852,32 @@ Can't `add` to a memory location that isn't writeable.
     | }
     ? ForbiddenWriteError: a
 
+You can `add` a byte constant to a byte memory location.
+
+    | byte lives
+    | define main routine
+    |   inputs a, lives
+    |   outputs lives
+    |   trashes a, c, z, v, n
+    | {
+    |     st off, c
+    |     add lives, 3
+    | }
+    = ok
+
+`add`ing a byte constant to a byte memory location trashes `a`.
+
+    | byte lives
+    | define main routine
+    |   inputs a, lives
+    |   outputs lives
+    |   trashes c, z, v, n
+    | {
+    |     st off, c
+    |     add lives, 3
+    | }
+    ? UnmeaningfulOutputError: a
+
 You can `add` a word constant to a word memory location.
 
     | word score
@@ -996,6 +1022,32 @@ Can't `sub` to a memory location that isn't writeable.
     | }
     ? ForbiddenWriteError: a
 
+You can `sub` a byte constant from a byte memory location.
+
+    | byte lives
+    | define main routine
+    |   inputs a, lives
+    |   outputs lives
+    |   trashes a, c, z, v, n
+    | {
+    |     st on, c
+    |     sub lives, 3
+    | }
+    = ok
+
+`sub`ing a byte constant from a byte memory location trashes `a`.
+
+    | byte lives
+    | define main routine
+    |   inputs a, lives
+    |   outputs lives
+    |   trashes c, z, v, n
+    | {
+    |     st on, c
+    |     sub lives, 3
+    | }
+    ? UnmeaningfulOutputError: a
+
 You can `sub` a word constant from a word memory location.
 
     | word score

tests/SixtyPical Compilation.md

@@ -1025,6 +1025,37 @@ Copying to and from a vector table.
     = $0842   JMP ($0846)
     = $0845   RTS
 
+### add, sub
+
+Various modes of `add`.
+
+    | byte lives
+    | word score
+    | define main routine
+    |   inputs lives, score
+    |   outputs lives, score
+    |   trashes a, x, y, c, z, v, n
+    | {
+    |     ld a, 0
+    |     ld x, 0
+    |     ld y, 0
+    |     st off, c
+    |     add a, 7
+    |     add a, lives
+    |     // add x, 7
+    |     // add y, 7
+    |     add lives, 2
+    |     add score, 1999
+    | }
+    = $080D   CLC
+    = $080E   LDA $081F
+    = $0811   ADC #$CF
+    = $0813   STA $081F
+    = $0816   LDA $0820
+    = $0819   ADC #$07
+    = $081B   STA $0820
+    = $081E   RTS
+
 ### word operations
 
 Adding a constant word to a word memory location.