A Reversible MC68HC11 Simulator and Its Empirical Computational Complexity Charles Vermette CIS 4914 Senior Project August 7, 2001

Problem Solution Motivation Hard data is needed to prove theoretical behavior of simulation algorithms on a real architecture. Solution Simulate a real irreversible machine on a real reversible architecture and record time/space complexity. Motivation Why? Work will aid in research into reversible computing. Why me? Interested in subject matter. Some previous experience.

Literature Sources C. H. Bennett. Logical reversibility of computation. IBM J. Research and Development, 17(6):525-532, 1973. C.H. Bennett. Time/space trade-offs for reversible computation. SIAM J. Computing, 18(4):766-776, 1989. M. P. Frank. Reversibility for Efficient Computing. (unpublished manuscript), 1999. R. Y. Levine and A. T. Sherman. A note on Bennett’s time-space tradeoff for reversible computation. SIAM J. Computation, 19(4):673-677, 1990. M. Li, J. Tromp, P. Vitány.Reversible Simulation of Irreversible Computation. Physica D, 120:168-176, 1998. Motorola, Inc. M68HC11 E Series Programming Reference Guide. (product information pamphlet), 2000.

Work Completed Test program written and compiled. integer Floyd-Warshall algorithm. using gcc hc11 port http://home.worldnet.fr/~stcarrez/m68hc11_port.html Op code counting program written. outputs op codes used in program dump, total number of op codes and total unique op codes. Binary to R language translator written. converts a binary dump of a program segment to an R language array declaration statement Simulation step code written. All op codes detected have had simulation routines written. note: only 45/64 ops in current version due to accidental deletion

Simulator Architecture

Garbage Information Layout 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ccr | garbage | pc info pc info [7..0]: 7 - branch taken flag 6 - jump taken flag 5 - page x flag 2..0 - instruction length

C to HC11 Compilation Statistics Source file: apsp.c Length: 13 loc, 273 bytes Text Segment Dump: apsp.b Length: 897 bytes Output from opcount: Page 1 5 6 8 e 20 26 27 2d 2f 30 32 33 35 36 37 38 39 3c 3e 4a 4c 4f 5a 5f 6f 7e 80 83 8c 8e 8f a6 bd c3 cc ce d3 dc dd de df e3 ec ed ee ff Page 2 8 30 38 3c 8f a7 ce de df e3 ec ed Page 3 83 a3 ee ef Page 4 ee ef Total opcodes in file: 471 Distinct opcodes in file: 64

Program Embedding Use objcopy utility to produce binary dump of text segment Run bin2ra to convert the dump into an R language array Insert the output of bin2ra into the simulator source file Binary becomes R code $12$FF$05 (defarray [name] 18 255 5 )

Conclusions Bugs in R compiler were exposed and corrected Utility of R as a general purpose language was supported New R language constructs were discussed Work was begun to test behavior of Bennett89

Future Work Recover lost op code routines. Test op code routines. Code simulation segment routine. Get complexity measurements.