AI-directed software engineering
I direct AI to build compilers, virtual machines and emulators — the systems layer, where “looks plausible” is worth nothing and a wrong answer is a crash rather than a rendering glitch. Of 53 public projects, 52 contain no code written by me.
How this works
Getting a language model to emit plausible code is easy and nearly worthless at this layer. A compiler that mostly works produces binaries that mostly run.
No code written by a primate. This mark appears on every project here whose code I did not write — 52 of 53. The exception is cpmemu, which I started myself.
01
Byte-identical to the binary Microsoft shipped. Smaller than z88dk on all 47 tests of a suite someone else published. The 499 bytecodes Xerox recorded in 1983. 13,040 of 13,053 Pharo tests. None of those pass conditions are my opinion, and none of them can be argued with.
02
Proving a source reconstruction needed a byte-identical assembler first, so that got built first. The work is choosing what has to exist, in what order, for the final claim to mean anything — and knowing when an answer is confidently wrong.
03
Every commit carries a Co-Authored-By: Claude trailer. Clone any
repository and read the history. The claim on this page is checkable the same
way everything else here is.
This is the part I would actually be hired for. The typing is free now; deciding what correct means, and refusing output that passes my own tests but not somebody else’s, is not.
What I do
These are the engagements where I am genuinely faster than a generalist, because I have already made the mistakes.
01
Frontends, AST and peephole optimization, register allocation, and backends for architectures with genuinely hostile constraints. Parser generators and assembler/linker toolchains when the existing ones do not fit.
02
Bytecode interpreters, CPU cores, and system emulation — either faithfully at the hardware level, or by intercepting system calls and translating them to the host. Including the platforms that forbid a just-in-time compiler, where the interpreter has to carry the whole load.
03
Codebases in languages your team no longer staffs, binaries whose source was lost, and file formats with no living specification. Reconstruction, verification, and porting onto platforms that did not exist when the code was written.
Evidence
This is what the method above produces. Every result below has a pass condition somebody other than me defined, which is the only reason it is worth stating at all.
Microsoft’s MBASIC 5.21 source no longer exists. The reconstructed
MACRO-80 source in mbasic2025
assembles to a binary identical to the shipped mbasic.com — not
equivalent, identical.
uc80, a C compiler for the Z80, produced smaller binaries than z88dk on all 47 tests of a public benchmark suite. uplm80 matches the Digital Research PL/M-80 compiler on code size.
smalltalk80-2026
boots the original Xerox Smalltalk-80 image to the desktop on four platforms,
each reproducing the Xerox trace2 boot prefix — 499 bytecodes
— exactly. The VM core is a port of dbanay/Smalltalk under MIT; the
portability, loader and verification harness are mine.
iospharo runs stock Pharo 13 and 14 images on iOS, where the platform forbids a JIT. The interpreter alone passes 13,040 of 13,053 Pharo tests on Mac Catalyst (99.90%), and 99.55% on the iOS Simulator.
Open source
53 public repositories, all under github.com/avwohl. I am available for sponsored work on any of them, and for the same kind of work on yours.
Largest
Compilers, optimizers and linkers for the Z80, 8080 and i386; CP/M, MP/M and DOS emulators for six host platforms; four implementations of Microsoft BASIC; and a full set of Z-machine tools.
Browse retro projectsSmalltalk-80 and Pharo virtual machines for desktop, iOS and Android; image validators and headless test tooling; a Smalltalk source search engine; and an implementation of the Prograph visual language.
Browse Smalltalk projectsShared libraries, a client for the Internet Chess Club protocol, and notes on the genuinely awkward problem of keeping Xojo projects under version control.
Browse Xojo projectsTry it
No install, no account. These are the real emulators, compiled to WebAssembly.
A hardware-level Z80 emulator booting CP/M from ROM, with bank switching across 512 KB of ROM and RAM.
Boot CP/MThe C++ interpreter for Microsoft BASIC-80, compiled to WebAssembly, with an editor and a virtual filesystem.
Run MBASICA search engine for Smalltalk source and videos, indexing GitHub, SqueakSource and SmalltalkHub by dialect.
Search SmalltalkWriting
Microsoft's source for MBASIC 5.21 is gone. A reconstruction from a sibling version and a disassembly is only half the problem. The harder half is proving the reconstruction is right, and that proof needed a byte-identical assembler to be built first.
uc80 compiles C for the Z80 and CP/M and produces smaller binaries than z88dk on every test of a public suite. Most of the difference comes from one decision about where local variables live — and from being honest about which part of that comparison is meaningful.
cpmemu and romwbw_emu both run CP/M software and share the same Z80 core, but they sit at opposite levels of abstraction. One intercepts the operating system, the other emulates the hardware. Neither is the better design. They answer different questions.
Also
Small utilities for my own infrastructure and my own tooling.
An hourly watchdog that sweeps every AWS region and emails you about wasted spend. It reports idle EC2 instances, unattached EBS volumes, unassociated Elastic IPs and long-stale servers, and it measures load through SSM.
A resumable replacement for run-parts and cron.daily. It records when each script last succeeded, so a later run skips whatever already finished this day, week or month.
Skill files for Claude Code, mostly iOS and watchOS development: exact measurements, algorithms and worked examples. Claude Code loads a file only when the topic is relevant.
I take on compiler, runtime, emulation and legacy-recovery work, and sponsored development on the open-source projects above. Tell me what the system has to do and what “correct” means for it, and I will tell you honestly whether I am the right person.