Started work on spec for data storage types in VM

spec.org

@@ -36,6 +36,17 @@ others.
 Bytecode files are byte sequence which encode instructions for the
 virtual machine.  Any instruction (even with an operand) has one and
 only one byte sequence associated with it.
+* TODO Storage
+Two types of storage:
++ Data stack which all core VM routines manipulate and work on (FIFO)
++ Register space which is generally reserved for user space code
+  i.e. other than ~mov~ no other core VM routine manipulates the
+  registers
+* TODO Assembler conventions
+The standard library is allowed to use the first 8 words (64 bytes) of
+register space without regard to user applications, so it's
+recommended to use register space from the 9th (72nd bit) word onwards
+for user applications if standard library is to be used.
 * Footnotes
 [fn:2] ~NOOP~, ~HALT~, ~MDELETE~, ~MSIZE~, ~JUMP_*~