A Reversible MC68HC11 Simulator and Its Empirical Computational Complexity Charles Vermette CIS 4914 Senior Project May 30, 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.

Week Task 1-2 Read research material. 3-4 Design simulator. 5-8 Code and incrementally test simulator. 9 Test completed simulator. 10-11 Use simulator to simulate programs and gather complexity data 12 Analyze data to determine constant factors in space/time complexity. 13 Final report due. 14 Final presentation.

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 (unpublished manuscript), 1999.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.

Problems & Solutions Problem: Create a garbage stack in R language. Solution: No dynamic memory, so use array stack. No assignment, so use swap both to get clean memory and push garbage on. Problem: Reduce wasted memory in garbage stack. Solution: Pack all garbage information into a single 32-bit word.