Getting 5 test PCBs made. Maybe it'll even work the first time...

Phew, I have A LOT to learn about routing.

Been having an intermittent crash on one of my older Commodore 64s.

I suspected a marginal RAM chip right away. This did not show up until the 6th pass of the Diagnostic cart.

Always building.

This speaker is the best upgrade I’ve made to my office in 2026.

Somewhere around episode 8 of Curious Marc's (and Mike's) Apollo Guidance Computer series (like 7 years ago), I decided to try to understand the system better. I've been writing code to implement the internals (Block II), with help from Frank O'Brien's book and a ton of work by e AGC and explaining how some more obscure components work.

I suspect I have some parts of it wrong, but to better visualize and push my understanding further, I realized that the TUI from my CROSSWOZ multi-vintage CPU interface would be a good way to figure out where I might be going wrong in my understanding of the internals.

So after a couple of weeks of wiring up my old AGC code to the TUI, I have a pretty good way to watch the whole thing run.

There's a TUI DSKY, Rope loader, real-time visualizer of registers and memory locations, built-in help, single step and breakpoint modes, real-time disassembly of running code, and more.

I borrowed a lot of my own code, so it was nice not to have to start the TUI from scratch. The speed is simulated (ish) as it's running on a Mac terminal.

As this is intended entirely for me to understand how the AGC works, zero lines of this were done by an LLM (didn't exist when I started the project anyway).

There's still a lot of work to do. I don't think some of my CPU internals are correct. I should probably start writing tests... (sigh)

And before you ask, I won't be releasing this. This is a learning project for me. A sort of document for myself by implementing a project. Some of it is spaghetti code, and that's fine with me. If you want to be a good engineer, there are no shortcuts. Do. The. Reps.

BTW, the HP-16C calculator is the only one I know of that can natively do one's complement like the AGG. Set the word size to 15, switch to one's complement, and change to Octal mode. Super useful for understanding the AGC.

I have an HP-16C calculator (free) in the Apple App Store.

It's a surreal experience, mostly because they call it a "Store". People have strange expectations about consumer products these days. Like they are owed something.

It's not all that unexpected. I've been giving away 0+ years and have more exposure to these things than the average person, but sometimes I wake up to very gruff emails that border on insulting.

I ALWAYS respond to such messages with kindness.

It's a very large codebase, and I've had to reverse-engineer many parts of the VERY obscure, quirky, and relatively unpopular calculator from the 80s.

I'm a single developer and don't want to make a penny from it. Really, the only reason I put it on the App Store in the first place is that I wanted it on my phone, and Apple makes it SUPER hard to install your own stuff on your phone.

In fact, thanks to Apple's silliness, it costs me $99/year just to give it away, only to get angry letters when some of the more obscure parts of an obscure calculator from 45 years ago don't work as expected.

I always fix whatever problems there are, but I can't help feeling like I'm standing at a trailhead, giving away free hot dogs. Someone takes one, then throws it on the ground because it's a Vienna Beef and not a Nathan's dog.

I love pretty much every pre-1990 computer ever made. But my favorite by a long shot is the Apollo AGC. This is my second time through this book.

The frontier model doesn’t do my work. It builds the tool that does my work. That’s the move.

milkcrunch.com/rent-the-build…

Look what I found at a yard sale. Neato.

CROSSWOZ wouldn't be complete without MS BASIC on the 6502 (with the 1970s easter egg) and a 10 PRINT.

Next up is to port it to Mister FPGA and then a standalone PCB.

Added the TMS 9900 to CROSSWOZ. Happy Thursday!

It’s a logic analyzer kinda morning.

For the last few weeks, I've been writing a multi-CPU single-board computer like explorer. I'm calling it CROSSWOZ (Hat tip to Woz and the WOZMON).

Seven vintage CPU cores (6502, 65C02, Z80, 8080, 8085, 6809, 1802) share a 64K memory bus and the same WOZMON-style monitor.

I It's got a mini-assembler per CPU, JMON-style debug, and animated paper-tape I/O.

I'm pretty pleased with how it's turning out.

My Commodore 64 received first contact from the MSP mesh!!! #meshtastic #c64

I'm genuinely surprised that Elon hasn't made a Grok device that fits inside a HAL 9000 replica. This is one of my favorite things on my shelf, and you can easily fit an ESP32 with a speaker and microphone in it. HAL/Grok would be SOOO much cooler than Alexa.