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

2. 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.

3. Literature Sources
C. H. Bennett. Logical reversibility of computation. IBM J. Research and Development, 17(6): , 1973.
C.H. Bennett. Time/space trade-offs for reversible computation. SIAM J. Computing, 18(4): , 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 (unpublished manuscript), 1999.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): , 1990.
M. Li, J. Tromp, P. Vitány.Reversible Simulation of Irreversible Computation. Physica D, 120: , 1998.
Motorola, Inc. M68HC11 E Series Programming Reference Guide. (product information pamphlet), 2000.

4. Work Completed Test program written and compiled.
integer Floyd-Warshall algorithm.
using gcc hc11 port
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

5. Simulator Architecture

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

7. 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 d 2f c 3e 4a
4c 4f 5a 5f 6f 7e c 8e 8f a6 bd c3 cc ce d3 dc dd
de df e3 ec ed ee ff
Page 2
c 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

8. 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] )

9. 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

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