The Project:  Motivations  Specifications  Current Focus  
              Front Panel Logic  Cards
Events:       VCF East XIII  VCF West XIII  DEFCON 26  VCF Midwest 13  
              VCF East XIV  VCF West XIV  VCF Midwest 14
The Future:   Want a Cactus?

Events Where I've Exhibited The Cactus

Vintage Computer Festival East XIII

The Cactus was on display at Vintage Computer Festival East XIII in Wall, NJ on May 19 & 20, 2018. I explained why I built it, what motivations lead it its design choices, and where the project was headed. Visitors were welcome to try using the front panel, program in BASIC, and listen to me ramble. I used a Heathkit H89 as a serial terminal to program using BASIC. A friend connected up a dot matrix printer in parallel with the terminal, and also managed to copy over Lunar Lander one line at a time from my Toshiba Libretto 70CT. Playing games on the Cactus!

I also briefly replaced the 1MHz clock crystal with an external pulse generator. The system clock was brought down into the sub-100KHz range, going as low as a few dozen Hz at times just for fun. I garuntee you've never seen a 6502 move that slowly. BASIC runs really slowly at that speed, and it gives you some perspective on how much work is happening in such a brief moment in time within the 6502.

A friend filmed the Cactus while I had external pulse generator connected. You can see individual instructions go by on the indicators as it struggles to begin rendering text on my H89:

My exhibit!

Lunar Lander Front panel running

People learning about the Cactus

Despite not actually being a vintage computer, it was a major hit with visitors and fellow exhibitors. Quite frankly, I wasn't expecting such an overwhelmingly positive response.

Click here to view my photos from VCF East XIII

Vintage Computer Festival West 13

I exhibited the Cactus at VCF West on August 4th & 5th in Mountain View California, at the Computer History Museum. This was my first time at VCF West, and the atmosphere made for a different experience compared to VCF East. Erik Klein was kind enough to lend me the use of a Televideo 910 due to my considerable distance from home. The Cactus was transported in a customized flight case to ensure it arrived intact. However, due to poor packing on my part, the contents shifted on its 3000 mile journey. The Deposit switch and a pair of header pins on the Status Control card were damaged in transport, and required on-site repairs before the show began. Fortunately, I was able to effect repairs, and the rest of the weekend's demonstrations went smoothly.

A few weeks prior to the show, I discovered that the MOnSter 6502 would be in attendance, along with the good folks at Evil Mad Scientist Laboratories. I reached out to its creator, Eric Schlaepfer, and asked if he would be willing to combine our two machines in an experiment. He was interested, letting me know that as long as I adhered to the NMOS specification and clocked down to 50KHz, the two should be able to work together. Normally, the Cactus relies on the 65C02's Bus Enable pin to halt the CPU and allow the front panel logic to take over to provide the user with direct memory access. I built a new processor card with additional buffers to account for the lack of such a pin on the NMOS variant, and tested it with an original Commodore 6502 from 1983.

Once at VCF West, our first attempt on Saturday pointed out that I had neglected to buffer the Read/Write line, resulting in bus contention. On Sunday, Eric brought me a breadboard, some additional jumper wires, and a few tristate buffers from his stockpile. After splicing an additional 74LS245 into the NMOS card, and testing with an NMOS 6502, we decided to try again. Lo and behold, the Cactus and the MOnSter 6502 successfully booted into BASIC, and ran at 50KHz for about half an hour, creating a spectacular fusion of blinkenlights. That makes the Cactus the third machine to use the MOnSter 6502, and the first one that wasn't made by Eric. Needless to say, this was the highlight of my weekend.

The Cactus running with the MOnSter 6502

Click here to view my photos from VCF West XIII

DEFCON 26 Hardware Hacking Village

I gave a talk & demonstration at the DEFCON 26 HHV at 4PM on August 11th. I discussed the history of the front panel and 6502 machines, my design influences and inspirations, and demonstrated the machine in action. I was really happy with the level of interest on display by attendees. This time, the Cactus made it to the show in one piece and performed admirably. Out of respect for the DEFCON photo policy, I ended up with a very small amount of photos overall.

Pre-demo setup and debugging

Click here to download the video!
Here's a photo from the desert photoshoot I did before DEFCON got into full swing. Special thanks to 3Chip for taking these desert photos, and assisting me at DEFCON as the official Cactus Goon.

me and my masterpiece

Vintage Computer Festival Midwest 13

I exhibited the Cactus at VCF Midwest , September 15th & 16th in Elk Grove Village, Illinois. I also gave a talk on the subject, along with a history of various front panels to add some context to my project. If you're interested in watching me speak on the subject, the entirety of my talk is available courtesy of the VCFMW folks.

VCFMW table

Click here to view my photos from VCF Midwest 13

Vintage Computer Festival East XIV

I exhibited the Cactus a second time at VCF East XIV in Wall, NJ on May 4 & 5, 2019. I focused on displaying the improvements from last year, as well as providing historical context for the Cactus compared to other 1970s front panels with 6502's. Bill Sudbrink lent me an authentic OSI-300, Bill Degnan lent me a CGRS Microtech 6502 front panel (which may end up being for the matching S-100 card rather than the SYM-1), and TangentDelta lent me his ADM-3A (as a last minute replacement for my upset H89). Singularity assisted me in setting up and running my exhibit table for the duration of the weekend. Many thanks to all of them for thier help!

The Cactus's more robust front panel logic performed admirably, and the Cactus Seed (the minimal, test board) made its functional debut running the terminal for a significant chunk of time. Software controlled I/O and even the sound card were demonstrated at various points. I brought along an OSI Challenger 4P as a point of reference on the same BASIC used by the Cactus, to show the direction that 6502 kit machines went following the advent of the appliance home computer in 1977.

I was part of a panel discussion on Friday with Glitch & Bill Dudley on the subject of homebrew computing. We gave our perspectives on our projects, and answered questions from the audience.

the table grows!

Click here to view my photos from VCF East XIV

Vintage Computer Festival West XIV

I exhibited the Cactus at VCF West XIV in Mountain View, CA on August 3rd and 4th. Due to the limitations of checked airline bags, I had to reduce the exhibit's contents compared to VCF East. However, I still wanted to capture the forgotten history of 6502 front panels. For the second year in a row, Erik Klein lent me a Televideo 910 terminal to use which was much appreciated.

VCFW table

Once again, Eric Schlaepfer's exhibit booth was directly next to mine, so we bolted the MOnSter 6502 into the Cactus to demonstrate the interoperability of the two machines. Fortunately this time it was a simple plug & play approach, and everything worked great.

MOnSter Cactus 2: Revengence!

For the duration of the weekend, the Cactus performed reliably for visitor demos. I was asked some interesting questions by visitors, including a reporter from KQED. Most notably, I was interviwed by a popular vintage technology personality on youtube, AkBKuKU. He does a great job covering the feel of the event, and even recorded the MOnSter Cactus experiment. It was a blast!

Click here to view my photos from VCF West XIV

Vintage Computer Festival Midwest 14

I attended VCF Midwest 14 in Elmhurst, IL on September 14th and 15th, in its new, larger venue. Once again, I exhibited the Cactus, providing demonstrations, and giving others an opportunity to experience the front panel. The game 'ZNEK" by ZephyrZ80 was on display, and proved to be a hit! The high score is currently held by TX_Dj with 23 points. Thank you again to TangentDelta for lending me his blue ADM-3A to use as my terminal for the weekend. Thank you to all who attended and took the time to see the Cactus, and speak with me about the project.

The Cactus running ZNEK

Click here to view my photos from VCF Midwest 14

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This page was last updated on 6-8-2024