| This is another proof that Vim is perfectly compatible with Vi. |
| The URM macro package was written by Rudolf Koenig ("Rudi") |
| (rudolf@koeniglich.de) for hpux-vi in August 1991. |
| |
| Getting started: |
| |
| type |
| in your shell: vim urm<RETURN> |
| in vim: :so urm.vim<RETURN> |
| in vim: * (to load the registers and boot the URM-machine :-) |
| in vim: g (for 'go') and watch the fun. Per default, 3 and 4 |
| are multiplied. Watch the Program counter, it is |
| visible as a komma moving around. |
| |
| This is a "standard URM" (Universal register machine) interpreter. The URM |
| concept is used in theoretical computer science to aid in theorem proving. |
| Here it proves that vim is a general problem solver (if you bring enough |
| patience). |
| |
| The interpreter begins with register 1 (not 0), without macros and more-lines |
| capability. A dot marks the end of a program. (Bug: there must be a space |
| after the dot.) |
| |
| The registers are the first few lines, beginning with a '>' . |
| The program is the first line after the registers. |
| You should always initialize the registers required by the program. |
| |
| Output register: line 2 |
| Input registers: line 2 to ... |
| |
| Commands: |
| a<n> increment register <n> |
| s<n> decrement register <n> |
| <x>;<y> execute command <x> and then <y> |
| (<x>)<n> execute command <x> while register <n> is nonzero |
| . ("dot blank") halt the machine. |
| |
| Examples: |
| |
| Add register 2 to register 3: |
| (a2;s3)3. |
| Multiply register 2 with register 3: |
| (a4;a5;s2)2; ((a2;s4)4; s3; (a1;a4;s5)5; (a5;s1)1)3. |
| |
| There are more (complicated) examples in the file examples. |
| Note, undo may take a while after a division. |
| |