A python-based Intel 8080 disassembler and emulator. (All opcodes tested, with the exception of daa, because I don't have a good test routine for fixed-point decimal arithmetic).
The editor module is a text-based, interactive curses application. It has a number of different windows and views into the state, and accepts a variety of different commands for manipulating both the trace of the program, and the editor state.
My goal is to have a flexible, bidirectional environment for navigating through a program state. Currently, my traces support bi-directional stepping: Obviously, you cans step the state forward by stepping the emulator. Whenever the emulator steps forward, a diff object is created. The program trace in itself is essentially a sequence of state-diffs; since we capture state diffs, navigating bidirectionally through the program is possible.
The editor is handled through text-based input. The following is a table of the commands available:
| implemented | input | command name | description |
|---|---|---|---|
| ✓ | q |
quit | Stops the emulator running and quits the program. |
| ✓ | s [steps] |
step | Steps the emulator forward by [steps] instruction. Records a diff between the state before the step command and the state after, and appends it to the trace. |
The base directory needs to be part of the PYTHONPATH, so run this script as a module:
python -m edit # rather than python edit.pySimilarly, run pytest as a module to go test:
python -m pytest -v # -v optional; shows individual test identitiesThe intel 8080 processor has 244 unique opcodes, out of a possible 256. The remaining 12 unallocated opcodes are aliases for nop, jmp, call, and ret. They should not be used. If you run python -m pytest to test all the opcodes, it will report 243 opcodes tested. This is because a test for the daa instruction (Decimal Adjust Accumulator, for doing 4-bit binary coded decimal math) is not implemented on this emulator as of yet. Once I have a compelling test case for daa, I'll add the test.
- Matrix of 256 possible 1-byte instructions for the 8080. Super useful overview; useful reference for opcode coverage, disassembler, and emulator.
- List of all 8080 opcodes, along with opcode size (1, 2, or, 3 bytes). Another useful one; has information about the behavior of most (not all) opcodes.
- Intel 8080 Data Book. The whole thing.