#monster 6502

[commodorez]

The MOnSter 6502 - Eric Schlaepfer

VCF West XVIII

[commodorez]

VCF West 2019!  MOnSter Cactus 2: Revengence!

Last year, I got to connect the Cactus to the MOnSter 6502.  You know, this thing?

Well this year it was a plug-&-play deal, no messing around with breadboards and jumper wires.  We bolted one of the two MOnSter’s on display at Eric’s table into my homebrew, and started computing right away.  We ran BASIC, EWOZMON, a larson scanner, kill-the-bit, and a few other brief experiments.  I had a blast! 

[commodorez]

I had the honor of connecting the Cactus to the MOnSter 6502 at VCF West XIII.

For those of you unfamiliar, the MOnSter 6502 is functional transistor-scale MOS 6502 replica.  It uses 3218 transistors and 1019 resistors, plus quite a few LEDs to produce an amazing lightshow the likes of which the world has never seen before.  You can observe the inner machinations of the microprocessor at work and really get a sense of what’s going on at the die level.  The MOnSter had only been run with designs specifically tailored to it’s unique limitation: speed.  It can only run at a maximum of 60KHz, with 50KHz being the more ideal clock rate to my understanding.  This means that many 6502 computers simply can’t use the MOnSter due to dependencies on higher frequencies.

Eric Schlaepfer and I discussed the prospect of combining our projects in a brief abomination of science in the weeks leading up to VCF West.  I set to work building a board that would work specifically with the NMOS parts, adding in additional buffers to account for the lack of a Bus Enable pin.  I wasn’t sure if it would work -- I tend to miss something in my designs.

We had our first integration attempt on Saturday, using my dedicated NMOS CPU board for the Cactus.  There was bus contention on the R/W line causing issues, so we had to abort and I had to think of a way to solve the issue with my minimal kit of parts.

The next day, Eric supplied me with a breadboard, some jumper wires, and a few parts (namely tri-state buffers) from which I could cobble together a fix for the R/W line bus contention.  A test run with an original Commodore NMOS 6502 at 50KHz proved that I had fixed the problem, so we hooked in the MOnSter and turned on the power.  Success!  We got a BASIC prompt!

The Cactus is the first third-party computer to use the MOnSter successfully, and the third machine overall to run with it.  BASIC ran really slowly, but it was fun to watch how much processing occurs each time the enter key is pressed when entering text.  Blinkenlights of this scale have probably not been seen in computing since an IBM System/360 Model 91 was in service last.

Thank you Eric for working with me to create the quick fix that made this Frankensteinian abomination possible.  And a thank you to Lenore and Windell of Evil Mad Scientist Laboratories @evilmadlinks for putting up with my goofiness.  This was a fun experiment that I consider the highlight of VCF West for me.

[commodorez]

I exhibited the Cactus at VCF West on August 4th & 5th in Mountain View California, at the Computer History Museum. 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.  

[commodorez]

The IBM 1401 computer from 1959 operates at about 87KHz. The Cactus running with the MOnSter 6502 operates at 50KHz.

That means that based purely on clock speed, the 1401 is faster than a MOnSter Cactus. 

[commodorez]

VCF West XIII Closing Thoughts

This weekend was pure awesome. Today in particular.

I met Jeri Ellsworth for the first time since I was 16. She's an absolute wizard.

I played Space War on a PDP-1 computer.

I took a picture with Jason Scott and the Cactus. That guy is a legend, and the fact that he knows about me and my work is oh so nice to know.

I ran into Brian Benchoff of Hackaday, and finally got to show him my computer. He digs it. Even made a SECOND Hackaday post on it. Nice.

I got to meet Marc of Curious Marc on youtube, and thank him for his efforts to share history.

I watched an IBM 1401 computer from 1959 run a program, where it took my name on a punch card and printed out a giant page with it on an IBM 1403 Line Printer.

I saw a real OSI-300 again, and was given massive diagrams & schematics by the guy who brought it to the show (who found it in his garage just to show me). That was really nice of him.

I saw a real Data General Nova on display. This is the machine that showed Woz that you could creatively cut down on hardware and achieve the same results. This concept was taken to heart with the Cactus. I kinda want one more than I did before.

I won second place for Best Demonstration.

Met alot of really nice people from parts of the community I had never interacted with before.

I talked kit building with Oscar Vermeullen, the guy responsible for the PiDP-8 and 11. He gave me good advice.

I met another former Commodore employee.

I managed to fix damage the Cactus incurred during transit using minimal parts and tools.

I scored the entire year of Byte magazine issues from 1977.

Erik Klein of the Vintage Computer Forums (among other things) was kind enough to lend me a Televideo 910 terminal to use while I was at the show. It worked great!

A robot is delivered me oreos in my hotel room.

But the best thing of all? Eric Schlaepfer and I combined the MOnSter 6502 and the Cactus.

That's right. It's now the third machine to interface with the MOnSter, and the only computer not made by Eric himself to run his processor. I was honored to have the experience. The Cactus had a special NMOS board constructed just for this situation, which required minimal tweaking to get it to work right. We ran it at 50KHz for about 20 minutes - pictures are coming.

[vex-soluciones]

MOnSter 6502: Formidable reproducción a gran escala del clásico procesador 6502 Más de 40 años de historia en un proyecto espectacular Nota Completa >> MOnSter 6502: Formidable reproducción a gran escala del clásico procesador 6502