subNegTest fails

[mjkkirschner]

this fails because we only represent numbers using ushorts and can't represent negative numbers like this.

If we move to using shorts - then we can't index into memory locations over 32k unless we do some kind of offset when indexing... possible..

[mjkkirschner]

tried memory pages, but the assembly got pretty miserable.

if I move back to this experiment should re-design memory address commands to always require the page as part of operands, or to assume zero page and reset it before any access.

[mjkkirschner]

for now, this is implemented by giving up and using ints everywhere.