brainwagon

Okay, it’s been a long time since I wrote anything here. Not really a lot dramatic going on in life, I just have been spending my free time writing for Quora rather than my own blog. But I still am nerding out from time to time. Last night I dusted off an old project of […]

A couple days ago, one of my Twitter or Facebook friends (sadly, I forgot who, comment if it was you, and I’ll give you credit) pointed out this awesome page: Reversing Sinclair’s amazing 1974 calculator hack – half the ROM of the HP-35 It documented an interesting calculator made by Sinclair in the 1970s. It […]

Ken Boak had mentioned on twitter that someone was creating a blinken-lights front end for the simh simulator of the PDP-8, called the PiDP-8, since you can power the entire thing from a Raspberry Pi. Very cool, but not quite available yet. What was available from Oscar is the Kim-Uno, a simulator for the old […]

The last five or so years has been a remarkable period in computing. About five years ago, I began to fear that computing would be increasingly pre-packaged: that laptops and tablets would totally take over the market and the ability to find computers which were well suited for programming and experimentation would more and more […]

At the Maker Faire, I splurged for a little bit of computing hardware called the Beaglebone. It’s an $89 ARM based computer that runs at 700Mhz, and includes a MicroSD card slot and Ethernet, as well as a USB connector. I wasn’t sure what I was going to use it for, but I frankly can’t […]

Fellow hacker Eric Smith has released the code for an 8080 simulator. I spent a few hours hacking my own 8080 emulator a few months ago, and at least got it to run Tiny BASIC, but I was never quite successful in getting it to boot CP/M. Among some of the problems were that I […]

I found this manual to be informative as I continue my quest to making a properly functioning 8080 emulator. I’m learning lots, but still not quite there. This is just bookmarked for future reference. Digital Research CP/M ® Operating System Manual.

Okay, not 8080 bottles, but 99 bottles of beer anyway… [proof:~/adad] markv% ./adad ::: brainwagon 8080 emulator version 1.0 ::: 637 bytes of code loaded. 99 bottles of beer on the wall, 99 bottles of beer. Take one down, pass it around, 98 bottles of beer on the wall. 98 bottles of beer on the […]

After getting a version of Tiny BASIC running on my emulator, I was scanning around to try to find something else to run. And, of course, when you look, you find all sorts of cool stuff. I happened across this cool page which is an 8080 emulator which is written in Javascript, and runs entirely […]

I’ve made a tiny bit of headway, but also encountered a link which makes me envious of much greater hacking skill. Óscar Toledo did an 8080 emulator that can boot CP/M as part of the 19th International Obfuscated C Code Contest, winning Best of Show. Its brevity is the “soul of wit”. Check it out. […]

I spent some more time hacking on my emulator today. The key to getting an emulator to work is to have good, clear references on how the system works, and some example code that torture tests your simulator. Except for the DAA instruction (more on that later), the documentation for the 8080 is pretty good, […]

A couple of days ago I got intrigued by this cool project which ran CP/M on an AVR. The basic idea was to equip an AVR with an external RAM, and then write a compact 8080 emulator to run on the AVR. Instead of floppy drives, the AVR accesses data stored on a small SD […]